Fix race condition in XLogWaitForReplayOf()

ConditionVariablePrepareToSleep has this comment on it:

> * Caution: "before entering the loop" means you *must* test the exit
> * condition between calling ConditionVariablePrepareToSleep and calling
> * ConditionVariableSleep.  If that is inconvenient, omit calling
> * ConditionVariablePrepareToSleep.

We were not obeying that: we did not test the exit condition correctly
between the ConditionVariablePrepareToSleep and ConditionVariableSleep
calls, because the test that we had in between them only checked the
local 'replayRecPtr' variable, without updating it from shared memory.

That wasn't too serious, because the loop includes a 10 second
timeout, and would retry and succeed if the original update was
missed. Still, better fix it.

To fix, just remove the ConditionVariablePrepareToSleep() call. As the
comment says, that's also correct, and even more efficient if we
assume that sleeping is rare.

.config/nextest.toml

@@ -1,2 +1,2 @@
 [profile.default]
-slow-timeout = { period = "20s", terminate-after = 3 }
+slow-timeout = { period = "60s", terminate-after = 3 }

.github/actionlint.yml

@@ -1,12 +1,11 @@
 self-hosted-runner:
   labels:
     - arm64
-    - dev
     - gen3
     - large
-    # Remove `macos-14` from the list after https://github.com/rhysd/actionlint/pull/392 is merged.
-    - macos-14
+    - large-arm64
     - small
+    - small-arm64
     - us-east-2
 config-variables:
   - REMOTE_STORAGE_AZURE_CONTAINER

.github/workflows/build-build-tools-image.yml

@@ -39,7 +39,7 @@ jobs:
       matrix:
         arch: [ x64, arm64 ]
 
-    runs-on: ${{ fromJson(format('["self-hosted", "dev", "{0}"]', matrix.arch)) }}
+    runs-on: ${{ fromJson(format('["self-hosted", "gen3", "{0}"]', matrix.arch == 'arm64' && 'large-arm64' || 'large')) }}
 
     env:
       IMAGE_TAG: ${{ inputs.image-tag }}

.github/workflows/build_and_test.yml

@@ -236,27 +236,6 @@ jobs:
           submodules: true
           fetch-depth: 1
 
-      - name: Check Postgres submodules revision
-        shell: bash -euo pipefail {0}
-        run: |
-          # This is a temporary solution to ensure that the Postgres submodules revision is correct (i.e. the updated intentionally).
-          # Eventually it will be replaced by a regression test https://github.com/neondatabase/neon/pull/4603
-
-          FAILED=false
-          for postgres in postgres-v14 postgres-v15 postgres-v16; do
-            expected=$(cat vendor/revisions.json | jq --raw-output '."'"${postgres}"'"')
-            actual=$(git rev-parse "HEAD:vendor/${postgres}")
-            if [ "${expected}" != "${actual}" ]; then
-              echo >&2 "Expected ${postgres} rev to be at '${expected}', but it is at '${actual}'"
-              FAILED=true
-            fi
-          done
-
-          if [ "${FAILED}" = "true" ]; then
-            echo >&2 "Please update vendor/revisions.json if these changes are intentional"
-            exit 1
-          fi
-
       - name: Set pg 14 revision for caching
         id: pg_v14_rev
         run: echo pg_rev=$(git rev-parse HEAD:vendor/postgres-v14) >> $GITHUB_OUTPUT
@@ -362,6 +341,9 @@ jobs:
         env:
           NEXTEST_RETRIES: 3
         run: |
+          #nextest does not yet support running doctests
+          cargo test --doc $CARGO_FLAGS $CARGO_FEATURES
+
           for io_engine in std-fs tokio-epoll-uring ; do
             NEON_PAGESERVER_UNIT_TEST_VIRTUAL_FILE_IOENGINE=$io_engine ${cov_prefix} cargo nextest run $CARGO_FLAGS $CARGO_FEATURES
           done
@@ -564,9 +546,27 @@ jobs:
       # XXX: no coverage data handling here, since benchmarks are run on release builds,
       # while coverage is currently collected for the debug ones
 
+  report-benchmarks-failures:
+    needs: [ benchmarks, create-test-report ]
+    if: github.ref_name == 'main' && needs.benchmarks.result == 'failure'
+    runs-on: ubuntu-latest
+
+    steps:
+    - uses: slackapi/slack-github-action@v1
+      with:
+        channel-id: C060CNA47S9 # on-call-staging-storage-stream
+        slack-message: |
+          Benchmarks failed on main: ${{ github.event.head_commit.url }}
+
+          Allure report: ${{ needs.create-test-report.outputs.report-url }}
+      env:
+        SLACK_BOT_TOKEN: ${{ secrets.SLACK_BOT_TOKEN }}
+
   create-test-report:
     needs: [ check-permissions, regress-tests, coverage-report, benchmarks, build-build-tools-image ]
     if: ${{ !cancelled() && contains(fromJSON('["skipped", "success"]'), needs.check-permissions.result) }}
+    outputs:
+      report-url: ${{ steps.create-allure-report.outputs.report-url }}
 
     runs-on: [ self-hosted, gen3, small ]
     container:

.github/workflows/neon_extra_builds.yml

@@ -136,7 +136,7 @@ jobs:
   check-linux-arm-build:
     needs: [ check-permissions, build-build-tools-image ]
     timeout-minutes: 90
-    runs-on: [ self-hosted, dev, arm64 ]
+    runs-on: [ self-hosted, small-arm64 ]
 
     env:
       # Use release build only, to have less debug info around
@@ -232,20 +232,20 @@ jobs:
 
       - name: Run cargo build
         run: |
-          mold -run cargo build --locked $CARGO_FLAGS $CARGO_FEATURES --bins --tests
+          mold -run cargo build --locked $CARGO_FLAGS $CARGO_FEATURES --bins --tests -j$(nproc)
 
       - name: Run cargo test
         env:
           NEXTEST_RETRIES: 3
         run: |
-          cargo nextest run $CARGO_FEATURES
+          cargo nextest run $CARGO_FEATURES -j$(nproc)
 
           # Run separate tests for real S3
           export ENABLE_REAL_S3_REMOTE_STORAGE=nonempty
           export REMOTE_STORAGE_S3_BUCKET=neon-github-ci-tests
           export REMOTE_STORAGE_S3_REGION=eu-central-1
           # Avoid `$CARGO_FEATURES` since there's no `testing` feature in the e2e tests now
-          cargo nextest run --package remote_storage --test test_real_s3
+          cargo nextest run --package remote_storage --test test_real_s3 -j$(nproc)
 
           # Run separate tests for real Azure Blob Storage
           # XXX: replace region with `eu-central-1`-like region
@@ -255,12 +255,12 @@ jobs:
           export REMOTE_STORAGE_AZURE_CONTAINER="${{ vars.REMOTE_STORAGE_AZURE_CONTAINER }}"
           export REMOTE_STORAGE_AZURE_REGION="${{ vars.REMOTE_STORAGE_AZURE_REGION }}"
           # Avoid `$CARGO_FEATURES` since there's no `testing` feature in the e2e tests now
-          cargo nextest run --package remote_storage --test test_real_azure
+          cargo nextest run --package remote_storage --test test_real_azure -j$(nproc)
 
   check-codestyle-rust-arm:
     needs: [ check-permissions, build-build-tools-image ]
     timeout-minutes: 90
-    runs-on: [ self-hosted, dev, arm64 ]
+    runs-on: [ self-hosted, small-arm64 ]
 
     container:
       image: ${{ needs.build-build-tools-image.outputs.image }}
@@ -269,6 +269,11 @@ jobs:
         password: ${{ secrets.NEON_DOCKERHUB_PASSWORD }}
       options: --init
 
+    strategy:
+      fail-fast: false
+      matrix:
+        build_type: [ debug, release ]
+
     steps:
       - name: Fix git ownership
         run: |
@@ -305,31 +310,35 @@ jobs:
             exit 1
           fi
           echo "CLIPPY_COMMON_ARGS=${CLIPPY_COMMON_ARGS}" >> $GITHUB_ENV
+
       - name: Run cargo clippy (debug)
+        if: matrix.build_type == 'debug'
         run: cargo hack --feature-powerset clippy $CLIPPY_COMMON_ARGS
       - name: Run cargo clippy (release)
+        if: matrix.build_type == 'release'
         run: cargo hack --feature-powerset clippy --release $CLIPPY_COMMON_ARGS
 
       - name: Check documentation generation
-        run: cargo doc --workspace --no-deps --document-private-items
+        if: matrix.build_type == 'release'
+        run: cargo doc --workspace --no-deps --document-private-items -j$(nproc)
         env:
             RUSTDOCFLAGS: "-Dwarnings -Arustdoc::private_intra_doc_links"
 
       # Use `${{ !cancelled() }}` to run quck tests after the longer clippy run
       - name: Check formatting
-        if: ${{ !cancelled() }}
+        if: ${{ !cancelled() && matrix.build_type == 'release' }}
         run: cargo fmt --all -- --check
 
       # https://github.com/facebookincubator/cargo-guppy/tree/bec4e0eb29dcd1faac70b1b5360267fc02bf830e/tools/cargo-hakari#2-keep-the-workspace-hack-up-to-date-in-ci
       - name: Check rust dependencies
-        if: ${{ !cancelled() }}
+        if: ${{ !cancelled() && matrix.build_type == 'release' }}
         run: |
           cargo hakari generate --diff  # workspace-hack Cargo.toml is up-to-date
           cargo hakari manage-deps --dry-run  # all workspace crates depend on workspace-hack
 
       # https://github.com/EmbarkStudios/cargo-deny
       - name: Check rust licenses/bans/advisories/sources
-        if: ${{ !cancelled() }}
+        if: ${{ !cancelled() && matrix.build_type == 'release' }}
         run: cargo deny check
 
   gather-rust-build-stats:
@@ -338,7 +347,7 @@ jobs:
       contains(github.event.pull_request.labels.*.name, 'run-extra-build-stats') ||
       contains(github.event.pull_request.labels.*.name, 'run-extra-build-*') ||
       github.ref_name == 'main'
-    runs-on: [ self-hosted, gen3, large ]
+    runs-on: [ self-hosted, large ]
     container:
       image: ${{ needs.build-build-tools-image.outputs.image }}
       credentials:
@@ -369,7 +378,7 @@ jobs:
         run: make walproposer-lib -j$(nproc)
 
       - name: Produce the build stats
-        run: cargo build --all --release --timings
+        run: cargo build --all --release --timings -j$(nproc)
 
       - name: Upload the build stats
         id: upload-stats

Cargo.toml

@@ -52,14 +52,14 @@ azure_storage_blobs = "0.19"
 flate2 = "1.0.26"
 async-stream = "0.3"
 async-trait = "0.1"
-aws-config = { version = "1.1.4", default-features = false, features=["rustls"] }
-aws-sdk-s3 = "1.14"
+aws-config = { version = "1.3", default-features = false, features=["rustls"] }
+aws-sdk-s3 = "1.26"
 aws-sdk-iam = "1.15.0"
-aws-smithy-async = { version = "1.1.4", default-features = false, features=["rt-tokio"] }
-aws-smithy-types = "1.1.4"
-aws-credential-types = "1.1.4"
-aws-sigv4 = { version = "1.2.0", features = ["sign-http"] }
-aws-types = "1.1.7"
+aws-smithy-async = { version = "1.2.1", default-features = false, features=["rt-tokio"] }
+aws-smithy-types = "1.1.9"
+aws-credential-types = "1.2.0"
+aws-sigv4 = { version = "1.2.1", features = ["sign-http"] }
+aws-types = "1.2.0"
 axum = { version = "0.6.20", features = ["ws"] }
 base64 = "0.13.0"
 bincode = "1.3"
@@ -81,13 +81,14 @@ enum-map = "2.4.2"
 enumset = "1.0.12"
 fail = "0.5.0"
 fallible-iterator = "0.2"
+framed-websockets = { version = "0.1.0", git = "https://github.com/neondatabase/framed-websockets" }
 fs2 = "0.4.3"
 futures = "0.3"
 futures-core = "0.3"
 futures-util = "0.3"
 git-version = "0.3"
-hashbrown = "0.13"
-hashlink = "0.8.4"
+hashbrown = "0.14"
+hashlink = "0.9.1"
 hdrhistogram = "7.5.2"
 hex = "0.4"
 hex-literal = "0.4"
@@ -98,7 +99,8 @@ http-types = { version = "2", default-features = false }
 humantime = "2.1"
 humantime-serde = "1.1.1"
 hyper = "0.14"
-hyper-tungstenite = "0.13.0"
+tokio-tungstenite = "0.20.0"
+indexmap = "2"
 inotify = "0.10.2"
 ipnet = "2.9.0"
 itertools = "0.10"
@@ -130,10 +132,10 @@ prost = "0.11"
 rand = "0.8"
 redis = { version = "0.25.2", features = ["tokio-rustls-comp", "keep-alive"] }
 regex = "1.10.2"
-reqwest = { version = "0.11", default-features = false, features = ["rustls-tls"] }
-reqwest-tracing = { version = "0.4.7", features = ["opentelemetry_0_20"] }
-reqwest-middleware = "0.2.0"
-reqwest-retry = "0.2.2"
+reqwest = { version = "0.12", default-features = false, features = ["rustls-tls"] }
+reqwest-tracing = { version = "0.5", features = ["opentelemetry_0_20"] }
+reqwest-middleware = "0.3.0"
+reqwest-retry = "0.5"
 routerify = "3"
 rpds = "0.13"
 rustc-hash = "1.1.0"
@@ -143,7 +145,7 @@ rustls-split = "0.3"
 scopeguard = "1.1"
 sysinfo = "0.29.2"
 sd-notify = "0.4.1"
-sentry = { version = "0.31", default-features = false, features = ["backtrace", "contexts", "panic", "rustls", "reqwest" ] }
+sentry = { version = "0.32", default-features = false, features = ["backtrace", "contexts", "panic", "rustls", "reqwest" ] }
 serde = { version = "1.0", features = ["derive"] }
 serde_json = "1"
 serde_path_to_error = "0.1"
@@ -157,8 +159,8 @@ socket2 = "0.5"
 strum = "0.24"
 strum_macros = "0.24"
 "subtle"  = "2.5.0"
-# https://github.com/nical/rust_debug/pull/4
-svg_fmt = { git = "https://github.com/neondatabase/fork--nical--rust_debug", branch = "neon" }
+# Our PR https://github.com/nical/rust_debug/pull/4 has been merged but no new version released yet
+svg_fmt = { git = "https://github.com/nical/rust_debug", rev = "28a7d96eecff2f28e75b1ea09f2d499a60d0e3b4" }
 sync_wrapper = "0.1.2"
 tar = "0.4"
 task-local-extensions = "0.1.4"
@@ -177,9 +179,10 @@ tokio-util = { version = "0.7.10", features = ["io", "rt"] }
 toml = "0.7"
 toml_edit = "0.19"
 tonic = {version = "0.9", features = ["tls", "tls-roots"]}
+tower-service = "0.3.2"
 tracing = "0.1"
 tracing-error = "0.2.0"
-tracing-opentelemetry = "0.20.0"
+tracing-opentelemetry = "0.21.0"
 tracing-subscriber = { version = "0.3", default_features = false, features = ["smallvec", "fmt", "tracing-log", "std", "env-filter", "json", "ansi"] }
 twox-hash = { version = "1.6.3", default-features = false }
 url = "2.2"

Dockerfile.build-tools

@@ -65,7 +65,7 @@ RUN curl -sL "https://github.com/peak/s5cmd/releases/download/v${S5CMD_VERSION}/
     && mv s5cmd /usr/local/bin/s5cmd
 
 # LLVM
-ENV LLVM_VERSION=17
+ENV LLVM_VERSION=18
 RUN curl -fsSL 'https://apt.llvm.org/llvm-snapshot.gpg.key' | apt-key add - \
     && echo "deb http://apt.llvm.org/bullseye/ llvm-toolchain-bullseye-${LLVM_VERSION} main" > /etc/apt/sources.list.d/llvm.stable.list \
     && apt update \
@@ -87,7 +87,7 @@ RUN curl "https://awscli.amazonaws.com/awscli-exe-linux-$(uname -m).zip" -o "aws
     && rm awscliv2.zip
 
 # Mold: A Modern Linker
-ENV MOLD_VERSION v2.4.0
+ENV MOLD_VERSION v2.31.0
 RUN set -e \
     && git clone https://github.com/rui314/mold.git \
     && mkdir mold/build \
@@ -141,7 +141,7 @@ WORKDIR /home/nonroot
 
 # Rust
 # Please keep the version of llvm (installed above) in sync with rust llvm (`rustc --version --verbose | grep LLVM`)
-ENV RUSTC_VERSION=1.77.0
+ENV RUSTC_VERSION=1.78.0
 ENV RUSTUP_HOME="/home/nonroot/.rustup"
 ENV PATH="/home/nonroot/.cargo/bin:${PATH}"
 RUN curl -sSO https://static.rust-lang.org/rustup/dist/$(uname -m)-unknown-linux-gnu/rustup-init && whoami && \

Makefile

@@ -81,11 +81,14 @@ $(POSTGRES_INSTALL_DIR)/build/%/config.status:
 		echo "'git submodule update --init --recursive --depth 2 --progress .' in project root.\n"; \
 		exit 1; }
 	mkdir -p $(POSTGRES_INSTALL_DIR)/build/$*
-	(cd $(POSTGRES_INSTALL_DIR)/build/$* && \
-	env PATH="$(EXTRA_PATH_OVERRIDES):$$PATH" $(ROOT_PROJECT_DIR)/vendor/postgres-$*/configure \
+
+	VERSION=$*; \
+	EXTRA_VERSION=$$(cd $(ROOT_PROJECT_DIR)/vendor/postgres-$$VERSION && git rev-parse HEAD); \
+	(cd $(POSTGRES_INSTALL_DIR)/build/$$VERSION && \
+	env PATH="$(EXTRA_PATH_OVERRIDES):$$PATH" $(ROOT_PROJECT_DIR)/vendor/postgres-$$VERSION/configure \
 		CFLAGS='$(PG_CFLAGS)' \
-		$(PG_CONFIGURE_OPTS) \
-		--prefix=$(abspath $(POSTGRES_INSTALL_DIR))/$* > configure.log)
+		$(PG_CONFIGURE_OPTS) --with-extra-version=" ($$EXTRA_VERSION)" \
+		--prefix=$(abspath $(POSTGRES_INSTALL_DIR))/$$VERSION > configure.log)
 
 # nicer alias to run 'configure'
 # Note: I've been unable to use templates for this part of our configuration.

compute_tools/Cargo.toml

@@ -27,10 +27,12 @@ reqwest = { workspace = true, features = ["json"] }
 tokio = { workspace = true, features = ["rt", "rt-multi-thread"] }
 tokio-postgres.workspace = true
 tokio-util.workspace = true
+tokio-stream.workspace = true
 tracing.workspace = true
 tracing-opentelemetry.workspace = true
 tracing-subscriber.workspace = true
 tracing-utils.workspace = true
+thiserror.workspace = true
 url.workspace = true
 
 compute_api.workspace = true

compute_tools/src/bin/compute_ctl.rs

@@ -47,7 +47,7 @@ use chrono::Utc;
 use clap::Arg;
 use signal_hook::consts::{SIGQUIT, SIGTERM};
 use signal_hook::{consts::SIGINT, iterator::Signals};
-use tracing::{error, info};
+use tracing::{error, info, warn};
 use url::Url;
 
 use compute_api::responses::ComputeStatus;
@@ -63,6 +63,7 @@ use compute_tools::logger::*;
 use compute_tools::monitor::launch_monitor;
 use compute_tools::params::*;
 use compute_tools::spec::*;
+use compute_tools::swap::resize_swap;
 
 // this is an arbitrary build tag. Fine as a default / for testing purposes
 // in-case of not-set environment var
@@ -71,24 +72,29 @@ const BUILD_TAG_DEFAULT: &str = "latest";
 fn main() -> Result<()> {
     let (build_tag, clap_args) = init()?;
 
-    let (pg_handle, start_pg_result) =
-    {
+    let (pg_handle, start_pg_result) = {
         // Enter startup tracing context
         let _startup_context_guard = startup_context_from_env();
 
-        let cli_result = process_cli(&clap_args)?;
+        let cli_args = process_cli(&clap_args)?;
 
-        let wait_spec_result = wait_spec(build_tag, cli_result)?;
+        let cli_spec = try_spec_from_cli(&clap_args, &cli_args)?;
+
+        let wait_spec_result = wait_spec(build_tag, cli_args, cli_spec)?;
 
         start_postgres(&clap_args, wait_spec_result)?
 
-        // Startup is finished, exit the startup tracing context
+        // Startup is finished, exit the startup tracing span
     };
 
     // PostgreSQL is now running, if startup was successful. Wait until it exits.
     let wait_pg_result = wait_postgres(pg_handle)?;
 
-    cleanup_and_exit(start_pg_result, wait_pg_result)
+    let delay_exit = cleanup_after_postgres_exit(start_pg_result)?;
+
+    maybe_delay_exit(delay_exit);
+
+    deinit_and_exit(wait_pg_result);
 }
 
 fn init() -> Result<(String, clap::ArgMatches)> {
@@ -109,8 +115,63 @@ fn init() -> Result<(String, clap::ArgMatches)> {
     Ok((build_tag, cli().get_matches()))
 }
 
-fn startup_context_from_env() -> Option<opentelemetry::ContextGuard>
-{
+fn process_cli(matches: &clap::ArgMatches) -> Result<ProcessCliResult> {
+    let pgbin_default = "postgres";
+    let pgbin = matches
+        .get_one::<String>("pgbin")
+        .map(|s| s.as_str())
+        .unwrap_or(pgbin_default);
+
+    let ext_remote_storage = matches
+        .get_one::<String>("remote-ext-config")
+        // Compatibility hack: if the control plane specified any remote-ext-config
+        // use the default value for extension storage proxy gateway.
+        // Remove this once the control plane is updated to pass the gateway URL
+        .map(|conf| {
+            if conf.starts_with("http") {
+                conf.trim_end_matches('/')
+            } else {
+                "http://pg-ext-s3-gateway"
+            }
+        });
+
+    let http_port = *matches
+        .get_one::<u16>("http-port")
+        .expect("http-port is required");
+    let pgdata = matches
+        .get_one::<String>("pgdata")
+        .expect("PGDATA path is required");
+    let connstr = matches
+        .get_one::<String>("connstr")
+        .expect("Postgres connection string is required");
+    let spec_json = matches.get_one::<String>("spec");
+    let spec_path = matches.get_one::<String>("spec-path");
+    let resize_swap_on_bind = matches.get_flag("resize-swap-on-bind");
+
+    Ok(ProcessCliResult {
+        connstr,
+        pgdata,
+        pgbin,
+        ext_remote_storage,
+        http_port,
+        spec_json,
+        spec_path,
+        resize_swap_on_bind,
+    })
+}
+
+struct ProcessCliResult<'clap> {
+    connstr: &'clap str,
+    pgdata: &'clap str,
+    pgbin: &'clap str,
+    ext_remote_storage: Option<&'clap str>,
+    http_port: u16,
+    spec_json: Option<&'clap String>,
+    spec_path: Option<&'clap String>,
+    resize_swap_on_bind: bool,
+}
+
+fn startup_context_from_env() -> Option<opentelemetry::ContextGuard> {
     // Extract OpenTelemetry context for the startup actions from the
     // TRACEPARENT and TRACESTATE env variables, and attach it to the current
     // tracing context.
@@ -160,39 +221,14 @@ fn startup_context_from_env() -> Option<opentelemetry::ContextGuard>
     }
 }
 
-fn process_cli(
+fn try_spec_from_cli(
     matches: &clap::ArgMatches,
-) -> Result<ProcessCliResult> {
-    let pgbin_default = "postgres";
-    let pgbin = matches
-        .get_one::<String>("pgbin")
-        .map(|s| s.as_str())
-        .unwrap_or(pgbin_default);
-
-    let ext_remote_storage = matches
-        .get_one::<String>("remote-ext-config")
-        // Compatibility hack: if the control plane specified any remote-ext-config
-        // use the default value for extension storage proxy gateway.
-        // Remove this once the control plane is updated to pass the gateway URL
-        .map(|conf| {
-            if conf.starts_with("http") {
-                conf.trim_end_matches('/')
-            } else {
-                "http://pg-ext-s3-gateway"
-            }
-        });
-
-    let http_port = *matches
-        .get_one::<u16>("http-port")
-        .expect("http-port is required");
-    let pgdata = matches
-        .get_one::<String>("pgdata")
-        .expect("PGDATA path is required");
-    let connstr = matches
-        .get_one::<String>("connstr")
-        .expect("Postgres connection string is required");
-    let spec_json = matches.get_one::<String>("spec");
-    let spec_path = matches.get_one::<String>("spec-path");
+    ProcessCliResult {
+        spec_json,
+        spec_path,
+        ..
+    }: &ProcessCliResult,
+) -> Result<CliSpecParams> {
     let compute_id = matches.get_one::<String>("compute-id");
     let control_plane_uri = matches.get_one::<String>("control-plane-uri");
 
@@ -233,28 +269,13 @@ fn process_cli(
         }
     };
 
-    let result = ProcessCliResult {
-        // directly from CLI:
-        connstr,
-        pgdata,
-        pgbin,
-        ext_remote_storage,
-        http_port,
-        // others:
+    Ok(CliSpecParams {
         spec,
         live_config_allowed,
-    };
-
-    Ok(result)
+    })
 }
 
-struct ProcessCliResult<'clap> {
-    connstr: &'clap str,
-    pgdata: &'clap str,
-    pgbin: &'clap str,
-    ext_remote_storage: Option<&'clap str>,
-    http_port: u16,
-
+struct CliSpecParams {
     /// If a spec was provided via CLI or file, the [`ComputeSpec`]
     spec: Option<ComputeSpec>,
     live_config_allowed: bool,
@@ -267,10 +288,14 @@ fn wait_spec(
         pgdata,
         pgbin,
         ext_remote_storage,
+        resize_swap_on_bind,
         http_port,
+        ..
+    }: ProcessCliResult,
+    CliSpecParams {
         spec,
         live_config_allowed,
-    }: ProcessCliResult,
+    }: CliSpecParams,
 ) -> Result<WaitSpecResult> {
     let mut new_state = ComputeState::new();
     let spec_set;
@@ -299,14 +324,14 @@ fn wait_spec(
 
     // If this is a pooled VM, prewarm before starting HTTP server and becoming
     // available for binding. Prewarming helps Postgres start quicker later,
-    // because QEMU will already have it's memory allocated from the host, and
+    // because QEMU will already have its memory allocated from the host, and
     // the necessary binaries will already be cached.
     if !spec_set {
         compute.prewarm_postgres()?;
     }
 
-    // Launch http service first, so we were able to serve control-plane
-    // requests, while configuration is still in progress.
+    // Launch http service first, so that we can serve control-plane requests
+    // while configuration is still in progress.
     let _http_handle =
         launch_http_server(http_port, &compute).expect("cannot launch http endpoint thread");
 
@@ -324,34 +349,45 @@ fn wait_spec(
                 break;
             }
         }
+
+        // Record for how long we slept waiting for the spec.
+        let now = Utc::now();
+        state.metrics.wait_for_spec_ms = now
+            .signed_duration_since(state.start_time)
+            .to_std()
+            .unwrap()
+            .as_millis() as u64;
+
+        // Reset start time, so that the total startup time that is calculated later will
+        // not include the time that we waited for the spec.
+        state.start_time = now;
     }
 
-    Ok(WaitSpecResult { compute, http_port })
+    Ok(WaitSpecResult {
+        compute,
+        http_port,
+        resize_swap_on_bind,
+    })
 }
 
 struct WaitSpecResult {
     compute: Arc<ComputeNode>,
     // passed through from ProcessCliResult
     http_port: u16,
+    resize_swap_on_bind: bool,
 }
 
 fn start_postgres(
-    matches: &clap::ArgMatches,
-    WaitSpecResult { compute, http_port }: WaitSpecResult,
+    // need to allow unused because `matches` is only used if target_os = "linux"
+    #[allow(unused_variables)] matches: &clap::ArgMatches,
+    WaitSpecResult {
+        compute,
+        http_port,
+        resize_swap_on_bind,
+    }: WaitSpecResult,
 ) -> Result<(Option<PostgresHandle>, StartPostgresResult)> {
     // We got all we need, update the state.
     let mut state = compute.state.lock().unwrap();
-
-    // Record for how long we slept waiting for the spec.
-    state.metrics.wait_for_spec_ms = Utc::now()
-        .signed_duration_since(state.start_time)
-        .to_std()
-        .unwrap()
-        .as_millis() as u64;
-    // Reset start time to the actual start of the configuration, so that
-    // total startup time was properly measured at the end.
-    state.start_time = Utc::now();
-
     state.status = ComputeStatus::Init;
     compute.state_changed.notify_all();
 
@@ -359,34 +395,72 @@ fn start_postgres(
         "running compute with features: {:?}",
         state.pspec.as_ref().unwrap().spec.features
     );
+    // before we release the mutex, fetch the swap size (if any) for later.
+    let swap_size_bytes = state.pspec.as_ref().unwrap().spec.swap_size_bytes;
     drop(state);
 
     // Launch remaining service threads
     let _monitor_handle = launch_monitor(&compute);
     let _configurator_handle = launch_configurator(&compute);
 
+    let mut prestartup_failed = false;
+    let mut delay_exit = false;
+
+    // Resize swap to the desired size if the compute spec says so
+    if let (Some(size_bytes), true) = (swap_size_bytes, resize_swap_on_bind) {
+        // To avoid 'swapoff' hitting postgres startup, we need to run resize-swap to completion
+        // *before* starting postgres.
+        //
+        // In theory, we could do this asynchronously if SkipSwapon was enabled for VMs, but this
+        // carries a risk of introducing hard-to-debug issues - e.g. if postgres sometimes gets
+        // OOM-killed during startup because swap wasn't available yet.
+        match resize_swap(size_bytes) {
+            Ok(()) => {
+                let size_gib = size_bytes as f32 / (1 << 20) as f32; // just for more coherent display.
+                info!(%size_bytes, %size_gib, "resized swap");
+            }
+            Err(err) => {
+                let err = err.context("failed to resize swap");
+                error!("{err:#}");
+
+                // Mark compute startup as failed; don't try to start postgres, and report this
+                // error to the control plane when it next asks.
+                prestartup_failed = true;
+                let mut state = compute.state.lock().unwrap();
+                state.error = Some(format!("{err:?}"));
+                state.status = ComputeStatus::Failed;
+                compute.state_changed.notify_all();
+                delay_exit = true;
+            }
+        }
+    }
+
     let extension_server_port: u16 = http_port;
 
     // Start Postgres
-    let mut delay_exit = false;
-    let pg = match compute.start_compute(extension_server_port) {
-        Ok(pg) => Some(pg),
-        Err(err) => {
-            error!("could not start the compute node: {:#}", err);
-            let mut state = compute.state.lock().unwrap();
-            state.error = Some(format!("{:?}", err));
-            state.status = ComputeStatus::Failed;
-            // Notify others that Postgres failed to start. In case of configuring the
-            // empty compute, it's likely that API handler is still waiting for compute
-            // state change. With this we will notify it that compute is in Failed state,
-            // so control plane will know about it earlier and record proper error instead
-            // of timeout.
-            compute.state_changed.notify_all();
-            drop(state); // unlock
-            delay_exit = true;
-            None
-        }
-    };
+    let mut pg = None;
+    if !prestartup_failed {
+        pg = match compute.start_compute(extension_server_port) {
+            Ok(pg) => Some(pg),
+            Err(err) => {
+                error!("could not start the compute node: {:#}", err);
+                let mut state = compute.state.lock().unwrap();
+                state.error = Some(format!("{:?}", err));
+                state.status = ComputeStatus::Failed;
+                // Notify others that Postgres failed to start. In case of configuring the
+                // empty compute, it's likely that API handler is still waiting for compute
+                // state change. With this we will notify it that compute is in Failed state,
+                // so control plane will know about it earlier and record proper error instead
+                // of timeout.
+                compute.state_changed.notify_all();
+                drop(state); // unlock
+                delay_exit = true;
+                None
+            }
+        };
+    } else {
+        warn!("skipping postgres startup because pre-startup step failed");
+    }
 
     // Start the vm-monitor if directed to. The vm-monitor only runs on linux
     // because it requires cgroups.
@@ -462,9 +536,7 @@ struct StartPostgresResult {
     vm_monitor: Option<tokio::task::JoinHandle<Result<()>>>,
 }
 
-fn wait_postgres(
-    pg: Option<PostgresHandle>,
-) -> Result<WaitPostgresResult> {
+fn wait_postgres(pg: Option<PostgresHandle>) -> Result<WaitPostgresResult> {
     // Wait for the child Postgres process forever. In this state Ctrl+C will
     // propagate to Postgres and it will be shut down as well.
     let mut exit_code = None;
@@ -490,7 +562,7 @@ struct WaitPostgresResult {
     exit_code: Option<i32>,
 }
 
-fn cleanup_and_exit(
+fn cleanup_after_postgres_exit(
     StartPostgresResult {
         mut delay_exit,
         compute,
@@ -501,8 +573,7 @@ fn cleanup_and_exit(
         #[cfg(target_os = "linux")]
         rt,
     }: StartPostgresResult,
-    WaitPostgresResult { exit_code }: WaitPostgresResult,
-) -> Result<()> {
+) -> Result<bool> {
     // Terminate the vm_monitor so it releases the file watcher on
     // /sys/fs/cgroup/neon-postgres.
     // Note: the vm-monitor only runs on linux because it requires cgroups.
@@ -544,13 +615,19 @@ fn cleanup_and_exit(
         error!("error while checking for core dumps: {err:?}");
     }
 
+    Ok(delay_exit)
+}
+
+fn maybe_delay_exit(delay_exit: bool) {
     // If launch failed, keep serving HTTP requests for a while, so the cloud
     // control plane can get the actual error.
     if delay_exit {
         info!("giving control plane 30s to collect the error before shutdown");
         thread::sleep(Duration::from_secs(30));
     }
+}
 
+fn deinit_and_exit(WaitPostgresResult { exit_code }: WaitPostgresResult) -> ! {
     // Shutdown trace pipeline gracefully, so that it has a chance to send any
     // pending traces before we exit. Shutting down OTEL tracing provider may
     // hang for quite some time, see, for example:
@@ -662,6 +739,11 @@ fn cli() -> clap::Command {
                 )
                 .value_name("FILECACHE_CONNSTR"),
         )
+        .arg(
+            Arg::new("resize-swap-on-bind")
+                .long("resize-swap-on-bind")
+                .action(clap::ArgAction::SetTrue),
+        )
 }
 
 /// When compute_ctl is killed, send also termination signal to sync-safekeepers

compute_tools/src/catalog.rs

@@ -0,0 +1,116 @@
+use compute_api::{
+    responses::CatalogObjects,
+    spec::{Database, Role},
+};
+use futures::Stream;
+use postgres::{Client, NoTls};
+use std::{path::Path, process::Stdio, result::Result, sync::Arc};
+use tokio::{
+    io::{AsyncBufReadExt, BufReader},
+    process::Command,
+    task,
+};
+use tokio_stream::{self as stream, StreamExt};
+use tokio_util::codec::{BytesCodec, FramedRead};
+use tracing::warn;
+
+use crate::{
+    compute::ComputeNode,
+    pg_helpers::{get_existing_dbs, get_existing_roles},
+};
+
+pub async fn get_dbs_and_roles(compute: &Arc<ComputeNode>) -> anyhow::Result<CatalogObjects> {
+    let connstr = compute.connstr.clone();
+    task::spawn_blocking(move || {
+        let mut client = Client::connect(connstr.as_str(), NoTls)?;
+        let roles: Vec<Role>;
+        {
+            let mut xact = client.transaction()?;
+            roles = get_existing_roles(&mut xact)?;
+        }
+        let databases: Vec<Database> = get_existing_dbs(&mut client)?.values().cloned().collect();
+
+        Ok(CatalogObjects { roles, databases })
+    })
+    .await?
+}
+
+#[derive(Debug, thiserror::Error)]
+pub enum SchemaDumpError {
+    #[error("Database does not exist.")]
+    DatabaseDoesNotExist,
+    #[error("Failed to execute pg_dump.")]
+    IO(#[from] std::io::Error),
+}
+
+// It uses the pg_dump utility to dump the schema of the specified database.
+// The output is streamed back to the caller and supposed to be streamed via HTTP.
+//
+// Before return the result with the output, it checks that pg_dump produced any output.
+// If not, it tries to parse the stderr output to determine if the database does not exist
+// and special error is returned.
+//
+// To make sure that the process is killed when the caller drops the stream, we use tokio kill_on_drop feature.
+pub async fn get_database_schema(
+    compute: &Arc<ComputeNode>,
+    dbname: &str,
+) -> Result<impl Stream<Item = Result<bytes::Bytes, std::io::Error>>, SchemaDumpError> {
+    let pgbin = &compute.pgbin;
+    let basepath = Path::new(pgbin).parent().unwrap();
+    let pgdump = basepath.join("pg_dump");
+    let mut connstr = compute.connstr.clone();
+    connstr.set_path(dbname);
+    let mut cmd = Command::new(pgdump)
+        .arg("--schema-only")
+        .arg(connstr.as_str())
+        .stdout(Stdio::piped())
+        .stderr(Stdio::piped())
+        .kill_on_drop(true)
+        .spawn()?;
+
+    let stdout = cmd.stdout.take().ok_or_else(|| {
+        std::io::Error::new(std::io::ErrorKind::Other, "Failed to capture stdout.")
+    })?;
+
+    let stderr = cmd.stderr.take().ok_or_else(|| {
+        std::io::Error::new(std::io::ErrorKind::Other, "Failed to capture stderr.")
+    })?;
+
+    let mut stdout_reader = FramedRead::new(stdout, BytesCodec::new());
+    let stderr_reader = BufReader::new(stderr);
+
+    let first_chunk = match stdout_reader.next().await {
+        Some(Ok(bytes)) if !bytes.is_empty() => bytes,
+        Some(Err(e)) => {
+            return Err(SchemaDumpError::IO(e));
+        }
+        _ => {
+            let mut lines = stderr_reader.lines();
+            if let Some(line) = lines.next_line().await? {
+                if line.contains(&format!("FATAL:  database \"{}\" does not exist", dbname)) {
+                    return Err(SchemaDumpError::DatabaseDoesNotExist);
+                }
+                warn!("pg_dump stderr: {}", line)
+            }
+            tokio::spawn(async move {
+                while let Ok(Some(line)) = lines.next_line().await {
+                    warn!("pg_dump stderr: {}", line)
+                }
+            });
+
+            return Err(SchemaDumpError::IO(std::io::Error::new(
+                std::io::ErrorKind::Other,
+                "failed to start pg_dump",
+            )));
+        }
+    };
+    let initial_stream = stream::once(Ok(first_chunk.freeze()));
+    // Consume stderr and log warnings
+    tokio::spawn(async move {
+        let mut lines = stderr_reader.lines();
+        while let Ok(Some(line)) = lines.next_line().await {
+            warn!("pg_dump stderr: {}", line)
+        }
+    });
+    Ok(initial_stream.chain(stdout_reader.map(|res| res.map(|b| b.freeze()))))
+}

compute_tools/src/http/api.rs

@@ -5,17 +5,21 @@ use std::net::SocketAddr;
 use std::sync::Arc;
 use std::thread;
 
+use crate::catalog::SchemaDumpError;
+use crate::catalog::{get_database_schema, get_dbs_and_roles};
 use crate::compute::forward_termination_signal;
 use crate::compute::{ComputeNode, ComputeState, ParsedSpec};
 use compute_api::requests::ConfigurationRequest;
 use compute_api::responses::{ComputeStatus, ComputeStatusResponse, GenericAPIError};
 
 use anyhow::Result;
+use hyper::header::CONTENT_TYPE;
 use hyper::service::{make_service_fn, service_fn};
 use hyper::{Body, Method, Request, Response, Server, StatusCode};
 use tokio::task;
 use tracing::{error, info, warn};
 use tracing_utils::http::OtelName;
+use utils::http::request::must_get_query_param;
 
 fn status_response_from_state(state: &ComputeState) -> ComputeStatusResponse {
     ComputeStatusResponse {
@@ -133,6 +137,34 @@ async fn routes(req: Request<Body>, compute: &Arc<ComputeNode>) -> Response<Body
             }
         }
 
+        (&Method::GET, "/dbs_and_roles") => {
+            info!("serving /dbs_and_roles GET request",);
+            match get_dbs_and_roles(compute).await {
+                Ok(res) => render_json(Body::from(serde_json::to_string(&res).unwrap())),
+                Err(_) => {
+                    render_json_error("can't get dbs and roles", StatusCode::INTERNAL_SERVER_ERROR)
+                }
+            }
+        }
+
+        (&Method::GET, "/database_schema") => {
+            let database = match must_get_query_param(&req, "database") {
+                Err(e) => return e.into_response(),
+                Ok(database) => database,
+            };
+            info!("serving /database_schema GET request with database: {database}",);
+            match get_database_schema(compute, &database).await {
+                Ok(res) => render_plain(Body::wrap_stream(res)),
+                Err(SchemaDumpError::DatabaseDoesNotExist) => {
+                    render_json_error("database does not exist", StatusCode::NOT_FOUND)
+                }
+                Err(e) => {
+                    error!("can't get schema dump: {}", e);
+                    render_json_error("can't get schema dump", StatusCode::INTERNAL_SERVER_ERROR)
+                }
+            }
+        }
+
         // download extension files from remote extension storage on demand
         (&Method::POST, route) if route.starts_with("/extension_server/") => {
             info!("serving {:?} POST request", route);
@@ -303,10 +335,25 @@ fn render_json_error(e: &str, status: StatusCode) -> Response<Body> {
     };
     Response::builder()
         .status(status)
+        .header(CONTENT_TYPE, "application/json")
         .body(Body::from(serde_json::to_string(&error).unwrap()))
         .unwrap()
 }
 
+fn render_json(body: Body) -> Response<Body> {
+    Response::builder()
+        .header(CONTENT_TYPE, "application/json")
+        .body(body)
+        .unwrap()
+}
+
+fn render_plain(body: Body) -> Response<Body> {
+    Response::builder()
+        .header(CONTENT_TYPE, "text/plain")
+        .body(body)
+        .unwrap()
+}
+
 async fn handle_terminate_request(compute: &Arc<ComputeNode>) -> Result<(), (String, StatusCode)> {
     {
         let mut state = compute.state.lock().unwrap();

compute_tools/src/http/openapi_spec.yaml

@@ -68,6 +68,51 @@ paths:
               schema:
                 $ref: "#/components/schemas/Info"
 
+  /dbs_and_roles:
+    get:
+      tags:
+        - Info
+      summary: Get databases and roles in the catalog.
+      description: ""
+      operationId: getDbsAndRoles
+      responses:
+        200:
+          description: Compute schema objects
+          content:
+            application/json:
+              schema:
+                $ref: "#/components/schemas/DbsAndRoles"
+
+  /database_schema:
+    get:
+      tags:
+        - Info
+      summary: Get schema dump
+      parameters:
+        - name: database
+          in: query
+          description: Database name to dump.
+          required: true
+          schema:
+            type: string
+          example: "postgres"
+      description: Get schema dump in SQL format.
+      operationId: getDatabaseSchema
+      responses:
+        200:
+          description: Schema dump
+          content:
+            text/plain:
+              schema:
+                type: string
+                description: Schema dump in SQL format.
+        404:
+          description: Non existing database.
+          content:
+            application/json:
+              schema:
+                $ref: "#/components/schemas/GenericError"
+
   /check_writability:
     post:
       tags:
@@ -229,6 +274,73 @@ components:
         num_cpus:
           type: integer
 
+    DbsAndRoles:
+      type: object
+      description: Databases and Roles
+      required:
+        - roles
+        - databases
+      properties:
+        roles:
+          type: array
+          items:
+            $ref: "#/components/schemas/Role"
+        databases:
+          type: array
+          items:
+            $ref: "#/components/schemas/Database"
+
+    Database:
+      type: object
+      description: Database
+      required:
+        - name
+        - owner
+        - restrict_conn
+        - invalid
+      properties:
+        name:
+          type: string
+        owner:
+          type: string
+        options:
+          type: array
+          items:
+            $ref: "#/components/schemas/GenericOption"
+        restrict_conn:
+          type: boolean
+        invalid:
+          type: boolean
+
+    Role:
+      type: object
+      description: Role
+      required:
+        - name
+      properties:
+        name:
+          type: string
+        encrypted_password:
+          type: string
+        options:
+          type: array
+          items:
+            $ref: "#/components/schemas/GenericOption"
+
+    GenericOption:
+      type: object
+      description: Schema Generic option
+      required:
+        - name
+        - vartype
+      properties:
+        name:
+          type: string
+        value:
+          type: string
+        vartype:
+          type: string
+
     ComputeState:
       type: object
       required:

compute_tools/src/lib.rs

@@ -8,10 +8,12 @@ pub mod configurator;
 pub mod http;
 #[macro_use]
 pub mod logger;
+pub mod catalog;
 pub mod compute;
 pub mod extension_server;
 pub mod monitor;
 pub mod params;
 pub mod pg_helpers;
 pub mod spec;
+pub mod swap;
 pub mod sync_sk;

compute_tools/src/spec.rs

@@ -490,7 +490,7 @@ pub fn handle_databases(spec: &ComputeSpec, client: &mut Client) -> Result<()> {
                 "rename_db" => {
                     let new_name = op.new_name.as_ref().unwrap();
 
-                    if existing_dbs.get(&op.name).is_some() {
+                    if existing_dbs.contains_key(&op.name) {
                         let query: String = format!(
                             "ALTER DATABASE {} RENAME TO {}",
                             op.name.pg_quote(),

compute_tools/src/swap.rs

@@ -0,0 +1,36 @@
+use anyhow::{anyhow, Context};
+use tracing::warn;
+
+pub const RESIZE_SWAP_BIN: &str = "/neonvm/bin/resize-swap";
+
+pub fn resize_swap(size_bytes: u64) -> anyhow::Result<()> {
+    // run `/neonvm/bin/resize-swap --once {size_bytes}`
+    //
+    // Passing '--once' causes resize-swap to delete itself after successful completion, which
+    // means that if compute_ctl restarts later, we won't end up calling 'swapoff' while
+    // postgres is running.
+    //
+    // NOTE: resize-swap is not very clever. If present, --once MUST be the first arg.
+    let child_result = std::process::Command::new("/usr/bin/sudo")
+        .arg(RESIZE_SWAP_BIN)
+        .arg("--once")
+        .arg(size_bytes.to_string())
+        .spawn();
+
+    if matches!(&child_result, Err(e) if e.kind() == std::io::ErrorKind::NotFound) {
+        warn!("ignoring \"not found\" error from resize-swap to avoid swapoff while compute is running");
+        return Ok(());
+    }
+
+    child_result
+        .context("spawn() failed")
+        .and_then(|mut child| child.wait().context("wait() failed"))
+        .and_then(|status| match status.success() {
+            true => Ok(()),
+            false => Err(anyhow!("process exited with {status}")),
+        })
+        // wrap any prior error with the overall context that we couldn't run the command
+        .with_context(|| {
+            format!("could not run `/usr/bin/sudo {RESIZE_SWAP_BIN} --once {size_bytes}`")
+        })
+}

control_plane/Cargo.toml

@@ -28,6 +28,7 @@ serde_with.workspace = true
 tar.workspace = true
 thiserror.workspace = true
 toml.workspace = true
+toml_edit.workspace = true
 tokio.workspace = true
 tokio-postgres.workspace = true
 tokio-util.workspace = true

control_plane/src/bin/neon_local.rs

@@ -9,20 +9,23 @@ use anyhow::{anyhow, bail, Context, Result};
 use clap::{value_parser, Arg, ArgAction, ArgMatches, Command, ValueEnum};
 use compute_api::spec::ComputeMode;
 use control_plane::endpoint::ComputeControlPlane;
-use control_plane::local_env::{InitForceMode, LocalEnv};
-use control_plane::pageserver::{PageServerNode, PAGESERVER_REMOTE_STORAGE_DIR};
+use control_plane::local_env::{
+    InitForceMode, LocalEnv, NeonBroker, NeonLocalInitConf, NeonLocalInitPageserverConf,
+    SafekeeperConf,
+};
+use control_plane::pageserver::PageServerNode;
 use control_plane::safekeeper::SafekeeperNode;
 use control_plane::storage_controller::StorageController;
 use control_plane::{broker, local_env};
+use pageserver_api::config::{
+    DEFAULT_HTTP_LISTEN_PORT as DEFAULT_PAGESERVER_HTTP_PORT,
+    DEFAULT_PG_LISTEN_PORT as DEFAULT_PAGESERVER_PG_PORT,
+};
 use pageserver_api::controller_api::PlacementPolicy;
 use pageserver_api::models::{
     ShardParameters, TenantCreateRequest, TimelineCreateRequest, TimelineInfo,
 };
 use pageserver_api::shard::{ShardCount, ShardStripeSize, TenantShardId};
-use pageserver_api::{
-    DEFAULT_HTTP_LISTEN_PORT as DEFAULT_PAGESERVER_HTTP_PORT,
-    DEFAULT_PG_LISTEN_PORT as DEFAULT_PAGESERVER_PG_PORT,
-};
 use postgres_backend::AuthType;
 use postgres_connection::parse_host_port;
 use safekeeper_api::{
@@ -52,44 +55,6 @@ const DEFAULT_PG_VERSION: &str = "15";
 
 const DEFAULT_PAGESERVER_CONTROL_PLANE_API: &str = "http://127.0.0.1:1234/upcall/v1/";
 
-fn default_conf(num_pageservers: u16) -> String {
-    let mut template = format!(
-        r#"
-# Default built-in configuration, defined in main.rs
-control_plane_api = '{DEFAULT_PAGESERVER_CONTROL_PLANE_API}'
-
-[broker]
-listen_addr = '{DEFAULT_BROKER_ADDR}'
-
-[[safekeepers]]
-id = {DEFAULT_SAFEKEEPER_ID}
-pg_port = {DEFAULT_SAFEKEEPER_PG_PORT}
-http_port = {DEFAULT_SAFEKEEPER_HTTP_PORT}
-
-"#,
-    );
-
-    for i in 0..num_pageservers {
-        let pageserver_id = NodeId(DEFAULT_PAGESERVER_ID.0 + i as u64);
-        let pg_port = DEFAULT_PAGESERVER_PG_PORT + i;
-        let http_port = DEFAULT_PAGESERVER_HTTP_PORT + i;
-
-        template += &format!(
-            r#"
-[[pageservers]]
-id = {pageserver_id}
-listen_pg_addr = '127.0.0.1:{pg_port}'
-listen_http_addr = '127.0.0.1:{http_port}'
-pg_auth_type = '{trust_auth}'
-http_auth_type = '{trust_auth}'
-"#,
-            trust_auth = AuthType::Trust,
-        )
-    }
-
-    template
-}
-
 ///
 /// Timelines tree element used as a value in the HashMap.
 ///
@@ -133,7 +98,7 @@ fn main() -> Result<()> {
         let subcommand_result = match sub_name {
             "tenant" => rt.block_on(handle_tenant(sub_args, &mut env)),
             "timeline" => rt.block_on(handle_timeline(sub_args, &mut env)),
-            "start" => rt.block_on(handle_start_all(sub_args, &env)),
+            "start" => rt.block_on(handle_start_all(&env)),
             "stop" => rt.block_on(handle_stop_all(sub_args, &env)),
             "pageserver" => rt.block_on(handle_pageserver(sub_args, &env)),
             "storage_controller" => rt.block_on(handle_storage_controller(sub_args, &env)),
@@ -152,7 +117,7 @@ fn main() -> Result<()> {
     };
 
     match subcommand_result {
-        Ok(Some(updated_env)) => updated_env.persist_config(&updated_env.base_data_dir)?,
+        Ok(Some(updated_env)) => updated_env.persist_config()?,
         Ok(None) => (),
         Err(e) => {
             eprintln!("command failed: {e:?}");
@@ -341,48 +306,65 @@ fn parse_timeline_id(sub_match: &ArgMatches) -> anyhow::Result<Option<TimelineId
 }
 
 fn handle_init(init_match: &ArgMatches) -> anyhow::Result<LocalEnv> {
-    let num_pageservers = init_match
-        .get_one::<u16>("num-pageservers")
-        .expect("num-pageservers arg has a default");
-    // Create config file
-    let toml_file: String = if let Some(config_path) = init_match.get_one::<PathBuf>("config") {
+    let num_pageservers = init_match.get_one::<u16>("num-pageservers");
+
+    let force = init_match.get_one("force").expect("we set a default value");
+
+    // Create the in-memory `LocalEnv` that we'd normally load from disk in `load_config`.
+    let init_conf: NeonLocalInitConf = if let Some(config_path) =
+        init_match.get_one::<PathBuf>("config")
+    {
+        // User (likely the Python test suite) provided a description of the environment.
+        if num_pageservers.is_some() {
+            bail!("Cannot specify both --num-pageservers and --config, use key `pageservers` in the --config file instead");
+        }
         // load and parse the file
-        std::fs::read_to_string(config_path).with_context(|| {
+        let contents = std::fs::read_to_string(config_path).with_context(|| {
             format!(
                 "Could not read configuration file '{}'",
                 config_path.display()
             )
-        })?
+        })?;
+        toml_edit::de::from_str(&contents)?
     } else {
-        // Built-in default config
-        default_conf(*num_pageservers)
+        // User (likely interactive) did not provide a description of the environment, give them the default
+        NeonLocalInitConf {
+            control_plane_api: Some(Some(DEFAULT_PAGESERVER_CONTROL_PLANE_API.parse().unwrap())),
+            broker: NeonBroker {
+                listen_addr: DEFAULT_BROKER_ADDR.parse().unwrap(),
+            },
+            safekeepers: vec![SafekeeperConf {
+                id: DEFAULT_SAFEKEEPER_ID,
+                pg_port: DEFAULT_SAFEKEEPER_PG_PORT,
+                http_port: DEFAULT_SAFEKEEPER_HTTP_PORT,
+                ..Default::default()
+            }],
+            pageservers: (0..num_pageservers.copied().unwrap_or(1))
+                .map(|i| {
+                    let pageserver_id = NodeId(DEFAULT_PAGESERVER_ID.0 + i as u64);
+                    let pg_port = DEFAULT_PAGESERVER_PG_PORT + i;
+                    let http_port = DEFAULT_PAGESERVER_HTTP_PORT + i;
+                    NeonLocalInitPageserverConf {
+                        id: pageserver_id,
+                        listen_pg_addr: format!("127.0.0.1:{pg_port}"),
+                        listen_http_addr: format!("127.0.0.1:{http_port}"),
+                        pg_auth_type: AuthType::Trust,
+                        http_auth_type: AuthType::Trust,
+                        other: Default::default(),
+                    }
+                })
+                .collect(),
+            pg_distrib_dir: None,
+            neon_distrib_dir: None,
+            default_tenant_id: TenantId::from_array(std::array::from_fn(|_| 0)),
+            storage_controller: None,
+            control_plane_compute_hook_api: None,
+        }
     };
 
-    let pg_version = init_match
-        .get_one::<u32>("pg-version")
-        .copied()
-        .context("Failed to parse postgres version from the argument string")?;
-
-    let mut env =
-        LocalEnv::parse_config(&toml_file).context("Failed to create neon configuration")?;
-    let force = init_match.get_one("force").expect("we set a default value");
-    env.init(pg_version, force)
-        .context("Failed to initialize neon repository")?;
-
-    // Create remote storage location for default LocalFs remote storage
-    std::fs::create_dir_all(env.base_data_dir.join(PAGESERVER_REMOTE_STORAGE_DIR))?;
-
-    // Initialize pageserver, create initial tenant and timeline.
-    for ps_conf in &env.pageservers {
-        PageServerNode::from_env(&env, ps_conf)
-            .initialize(&pageserver_config_overrides(init_match))
-            .unwrap_or_else(|e| {
-                eprintln!("pageserver init failed: {e:?}");
-                exit(1);
-            });
-    }
-
-    Ok(env)
+    LocalEnv::init(init_conf, force)
+        .context("materialize initial neon_local environment on disk")?;
+    Ok(LocalEnv::load_config().expect("freshly written config should be loadable"))
 }
 
 /// The default pageserver is the one where CLI tenant/timeline operations are sent by default.
@@ -397,15 +379,6 @@ fn get_default_pageserver(env: &local_env::LocalEnv) -> PageServerNode {
     PageServerNode::from_env(env, ps_conf)
 }
 
-fn pageserver_config_overrides(init_match: &ArgMatches) -> Vec<&str> {
-    init_match
-        .get_many::<String>("pageserver-config-override")
-        .into_iter()
-        .flatten()
-        .map(String::as_str)
-        .collect()
-}
-
 async fn handle_tenant(
     tenant_match: &ArgMatches,
     env: &mut local_env::LocalEnv,
@@ -837,6 +810,8 @@ async fn handle_endpoint(ep_match: &ArgMatches, env: &local_env::LocalEnv) -> Re
                 .copied()
                 .unwrap_or(false);
 
+            let allow_multiple = sub_args.get_flag("allow-multiple");
+
             let mode = match (lsn, hot_standby) {
                 (Some(lsn), false) => ComputeMode::Static(lsn),
                 (None, true) => ComputeMode::Replica,
@@ -854,7 +829,9 @@ async fn handle_endpoint(ep_match: &ArgMatches, env: &local_env::LocalEnv) -> Re
                 _ => {}
             }
 
-            cplane.check_conflicting_endpoints(mode, tenant_id, timeline_id)?;
+            if !allow_multiple {
+                cplane.check_conflicting_endpoints(mode, tenant_id, timeline_id)?;
+            }
 
             cplane.new_endpoint(
                 &endpoint_id,
@@ -883,6 +860,8 @@ async fn handle_endpoint(ep_match: &ArgMatches, env: &local_env::LocalEnv) -> Re
 
             let remote_ext_config = sub_args.get_one::<String>("remote-ext-config");
 
+            let allow_multiple = sub_args.get_flag("allow-multiple");
+
             // If --safekeepers argument is given, use only the listed safekeeper nodes.
             let safekeepers =
                 if let Some(safekeepers_str) = sub_args.get_one::<String>("safekeepers") {
@@ -908,11 +887,13 @@ async fn handle_endpoint(ep_match: &ArgMatches, env: &local_env::LocalEnv) -> Re
                 .cloned()
                 .unwrap_or_default();
 
-            cplane.check_conflicting_endpoints(
-                endpoint.mode,
-                endpoint.tenant_id,
-                endpoint.timeline_id,
-            )?;
+            if !allow_multiple {
+                cplane.check_conflicting_endpoints(
+                    endpoint.mode,
+                    endpoint.tenant_id,
+                    endpoint.timeline_id,
+                )?;
+            }
 
             let (pageservers, stripe_size) = if let Some(pageserver_id) = pageserver_id {
                 let conf = env.get_pageserver_conf(pageserver_id).unwrap();
@@ -1068,10 +1049,7 @@ fn get_pageserver(env: &local_env::LocalEnv, args: &ArgMatches) -> Result<PageSe
 async fn handle_pageserver(sub_match: &ArgMatches, env: &local_env::LocalEnv) -> Result<()> {
     match sub_match.subcommand() {
         Some(("start", subcommand_args)) => {
-            if let Err(e) = get_pageserver(env, subcommand_args)?
-                .start(&pageserver_config_overrides(subcommand_args))
-                .await
-            {
+            if let Err(e) = get_pageserver(env, subcommand_args)?.start().await {
                 eprintln!("pageserver start failed: {e}");
                 exit(1);
             }
@@ -1097,10 +1075,7 @@ async fn handle_pageserver(sub_match: &ArgMatches, env: &local_env::LocalEnv) ->
                 exit(1);
             }
 
-            if let Err(e) = pageserver
-                .start(&pageserver_config_overrides(subcommand_args))
-                .await
-            {
+            if let Err(e) = pageserver.start().await {
                 eprintln!("pageserver start failed: {e}");
                 exit(1);
             }
@@ -1227,7 +1202,7 @@ async fn handle_safekeeper(sub_match: &ArgMatches, env: &local_env::LocalEnv) ->
     Ok(())
 }
 
-async fn handle_start_all(sub_match: &ArgMatches, env: &local_env::LocalEnv) -> anyhow::Result<()> {
+async fn handle_start_all(env: &local_env::LocalEnv) -> anyhow::Result<()> {
     // Endpoints are not started automatically
 
     broker::start_broker_process(env).await?;
@@ -1244,10 +1219,7 @@ async fn handle_start_all(sub_match: &ArgMatches, env: &local_env::LocalEnv) ->
 
     for ps_conf in &env.pageservers {
         let pageserver = PageServerNode::from_env(env, ps_conf);
-        if let Err(e) = pageserver
-            .start(&pageserver_config_overrides(sub_match))
-            .await
-        {
+        if let Err(e) = pageserver.start().await {
             eprintln!("pageserver {} start failed: {:#}", ps_conf.id, e);
             try_stop_all(env, true).await;
             exit(1);
@@ -1388,13 +1360,6 @@ fn cli() -> Command {
         .required(false)
         .value_name("stop-mode");
 
-    let pageserver_config_args = Arg::new("pageserver-config-override")
-        .long("pageserver-config-override")
-        .num_args(1)
-        .action(ArgAction::Append)
-        .help("Additional pageserver's configuration options or overrides, refer to pageserver's 'config-override' CLI parameter docs for more")
-        .required(false);
-
     let remote_ext_config_args = Arg::new("remote-ext-config")
         .long("remote-ext-config")
         .num_args(1)
@@ -1428,9 +1393,7 @@ fn cli() -> Command {
     let num_pageservers_arg = Arg::new("num-pageservers")
         .value_parser(value_parser!(u16))
         .long("num-pageservers")
-        .help("How many pageservers to create (default 1)")
-        .required(false)
-        .default_value("1");
+        .help("How many pageservers to create (default 1)");
 
     let update_catalog = Arg::new("update-catalog")
         .value_parser(value_parser!(bool))
@@ -1444,20 +1407,25 @@ fn cli() -> Command {
         .help("If set, will create test user `user` and `neondb` database. Requires `update-catalog = true`")
         .required(false);
 
+    let allow_multiple = Arg::new("allow-multiple")
+        .help("Allow multiple primary endpoints running on the same branch. Shouldn't be used normally, but useful for tests.")
+        .long("allow-multiple")
+        .action(ArgAction::SetTrue)
+        .required(false);
+
     Command::new("Neon CLI")
         .arg_required_else_help(true)
         .version(GIT_VERSION)
         .subcommand(
             Command::new("init")
                 .about("Initialize a new Neon repository, preparing configs for services to start with")
-                .arg(pageserver_config_args.clone())
                 .arg(num_pageservers_arg.clone())
                 .arg(
                     Arg::new("config")
                         .long("config")
                         .required(false)
                         .value_parser(value_parser!(PathBuf))
-                        .value_name("config"),
+                        .value_name("config")
                 )
                 .arg(pg_version_arg.clone())
                 .arg(force_arg)
@@ -1539,7 +1507,6 @@ fn cli() -> Command {
                 .subcommand(Command::new("status"))
                 .subcommand(Command::new("start")
                     .about("Start local pageserver")
-                    .arg(pageserver_config_args.clone())
                 )
                 .subcommand(Command::new("stop")
                     .about("Stop local pageserver")
@@ -1547,7 +1514,6 @@ fn cli() -> Command {
                 )
                 .subcommand(Command::new("restart")
                     .about("Restart local pageserver")
-                    .arg(pageserver_config_args.clone())
                 )
         )
         .subcommand(
@@ -1601,6 +1567,7 @@ fn cli() -> Command {
                     .arg(pg_version_arg.clone())
                     .arg(hot_standby_arg.clone())
                     .arg(update_catalog)
+                    .arg(allow_multiple.clone())
                 )
                 .subcommand(Command::new("start")
                     .about("Start postgres.\n If the endpoint doesn't exist yet, it is created.")
@@ -1609,6 +1576,7 @@ fn cli() -> Command {
                     .arg(safekeepers_arg)
                     .arg(remote_ext_config_args)
                     .arg(create_test_user)
+                    .arg(allow_multiple.clone())
                 )
                 .subcommand(Command::new("reconfigure")
                             .about("Reconfigure the endpoint")
@@ -1660,7 +1628,6 @@ fn cli() -> Command {
         .subcommand(
             Command::new("start")
                 .about("Start page server and safekeepers")
-                .arg(pageserver_config_args)
         )
         .subcommand(
             Command::new("stop")

control_plane/src/endpoint.rs

@@ -554,6 +554,7 @@ impl Endpoint {
             format_version: 1.0,
             operation_uuid: None,
             features: self.features.clone(),
+            swap_size_bytes: None,
             cluster: Cluster {
                 cluster_id: None, // project ID: not used
                 name: None,       // project name: not used

control_plane/src/local_env.rs

@@ -3,7 +3,7 @@
 //! Now it also provides init method which acts like a stub for proper installation
 //! script which will use local paths.
 
-use anyhow::{bail, ensure, Context};
+use anyhow::{bail, Context};
 
 use clap::ValueEnum;
 use postgres_backend::AuthType;
@@ -23,6 +23,8 @@ use utils::{
     id::{NodeId, TenantId, TenantTimelineId, TimelineId},
 };
 
+use crate::pageserver::PageServerNode;
+use crate::pageserver::PAGESERVER_REMOTE_STORAGE_DIR;
 use crate::safekeeper::SafekeeperNode;
 
 pub const DEFAULT_PG_VERSION: u32 = 15;
@@ -34,7 +36,7 @@ pub const DEFAULT_PG_VERSION: u32 = 15;
 // to 'neon_local init --config=<path>' option. See control_plane/simple.conf for
 // an example.
 //
-#[derive(Serialize, Deserialize, PartialEq, Eq, Clone, Debug)]
+#[derive(PartialEq, Eq, Clone, Debug)]
 pub struct LocalEnv {
     // Base directory for all the nodes (the pageserver, safekeepers and
     // compute endpoints).
@@ -42,59 +44,99 @@ pub struct LocalEnv {
     // This is not stored in the config file. Rather, this is the path where the
     // config file itself is. It is read from the NEON_REPO_DIR env variable or
     // '.neon' if not given.
-    #[serde(skip)]
     pub base_data_dir: PathBuf,
 
     // Path to postgres distribution. It's expected that "bin", "include",
     // "lib", "share" from postgres distribution are there. If at some point
     // in time we will be able to run against vanilla postgres we may split that
     // to four separate paths and match OS-specific installation layout.
-    #[serde(default)]
     pub pg_distrib_dir: PathBuf,
 
     // Path to pageserver binary.
-    #[serde(default)]
     pub neon_distrib_dir: PathBuf,
 
     // Default tenant ID to use with the 'neon_local' command line utility, when
     // --tenant_id is not explicitly specified.
-    #[serde(default)]
     pub default_tenant_id: Option<TenantId>,
 
     // used to issue tokens during e.g pg start
-    #[serde(default)]
     pub private_key_path: PathBuf,
 
     pub broker: NeonBroker,
 
     // Configuration for the storage controller (1 per neon_local environment)
-    #[serde(default)]
     pub storage_controller: NeonStorageControllerConf,
 
     /// This Vec must always contain at least one pageserver
+    /// Populdated by [`Self::load_config`] from the individual `pageserver.toml`s.
+    /// NB: not used anymore except for informing users that they need to change their `.neon/config`.
     pub pageservers: Vec<PageServerConf>,
 
-    #[serde(default)]
     pub safekeepers: Vec<SafekeeperConf>,
 
     // Control plane upcall API for pageserver: if None, we will not run storage_controller  If set, this will
     // be propagated into each pageserver's configuration.
-    #[serde(default)]
     pub control_plane_api: Option<Url>,
 
     // Control plane upcall API for storage controller.  If set, this will be propagated into the
     // storage controller's configuration.
-    #[serde(default)]
     pub control_plane_compute_hook_api: Option<Url>,
 
     /// Keep human-readable aliases in memory (and persist them to config), to hide ZId hex strings from the user.
-    #[serde(default)]
     // A `HashMap<String, HashMap<TenantId, TimelineId>>` would be more appropriate here,
     // but deserialization into a generic toml object as `toml::Value::try_from` fails with an error.
     // https://toml.io/en/v1.0.0 does not contain a concept of "a table inside another table".
+    pub branch_name_mappings: HashMap<String, Vec<(TenantId, TimelineId)>>,
+}
+
+/// On-disk state stored in `.neon/config`.
+#[derive(PartialEq, Eq, Clone, Debug, Default, Serialize, Deserialize)]
+#[serde(default, deny_unknown_fields)]
+pub struct OnDiskConfig {
+    pub pg_distrib_dir: PathBuf,
+    pub neon_distrib_dir: PathBuf,
+    pub default_tenant_id: Option<TenantId>,
+    pub private_key_path: PathBuf,
+    pub broker: NeonBroker,
+    pub storage_controller: NeonStorageControllerConf,
+    #[serde(
+        skip_serializing,
+        deserialize_with = "fail_if_pageservers_field_specified"
+    )]
+    pub pageservers: Vec<PageServerConf>,
+    pub safekeepers: Vec<SafekeeperConf>,
+    pub control_plane_api: Option<Url>,
+    pub control_plane_compute_hook_api: Option<Url>,
     branch_name_mappings: HashMap<String, Vec<(TenantId, TimelineId)>>,
 }
 
+fn fail_if_pageservers_field_specified<'de, D>(_: D) -> Result<Vec<PageServerConf>, D::Error>
+where
+    D: serde::Deserializer<'de>,
+{
+    Err(serde::de::Error::custom(
+        "The 'pageservers' field is no longer used; pageserver.toml is now authoritative; \
+         Please remove the `pageservers` from your .neon/config.",
+    ))
+}
+
+/// The description of the neon_local env to be initialized by `neon_local init --config`.
+#[derive(Clone, Debug, Deserialize)]
+#[serde(deny_unknown_fields)]
+pub struct NeonLocalInitConf {
+    // TODO: do we need this? Seems unused
+    pub pg_distrib_dir: Option<PathBuf>,
+    // TODO: do we need this? Seems unused
+    pub neon_distrib_dir: Option<PathBuf>,
+    pub default_tenant_id: TenantId,
+    pub broker: NeonBroker,
+    pub storage_controller: Option<NeonStorageControllerConf>,
+    pub pageservers: Vec<NeonLocalInitPageserverConf>,
+    pub safekeepers: Vec<SafekeeperConf>,
+    pub control_plane_api: Option<Option<Url>>,
+    pub control_plane_compute_hook_api: Option<Option<Url>>,
+}
+
 /// Broker config for cluster internal communication.
 #[derive(Serialize, Deserialize, PartialEq, Eq, Clone, Debug)]
 #[serde(default)]
@@ -110,6 +152,9 @@ pub struct NeonStorageControllerConf {
     /// Heartbeat timeout before marking a node offline
     #[serde(with = "humantime_serde")]
     pub max_unavailable: Duration,
+
+    /// Threshold for auto-splitting a tenant into shards
+    pub split_threshold: Option<u64>,
 }
 
 impl NeonStorageControllerConf {
@@ -122,6 +167,7 @@ impl Default for NeonStorageControllerConf {
     fn default() -> Self {
         Self {
             max_unavailable: Self::DEFAULT_MAX_UNAVAILABLE_INTERVAL,
+            split_threshold: None,
         }
     }
 }
@@ -141,24 +187,18 @@ impl NeonBroker {
     }
 }
 
+// neon_local needs to know this subset of pageserver configuration.
+// For legacy reasons, this information is duplicated from `pageserver.toml` into `.neon/config`.
+// It can get stale if `pageserver.toml` is changed.
+// TODO(christian): don't store this at all in `.neon/config`, always load it from `pageserver.toml`
 #[derive(Serialize, Deserialize, PartialEq, Eq, Clone, Debug)]
 #[serde(default, deny_unknown_fields)]
 pub struct PageServerConf {
-    // node id
     pub id: NodeId,
-
-    // Pageserver connection settings
     pub listen_pg_addr: String,
     pub listen_http_addr: String,
-
-    // auth type used for the PG and HTTP ports
     pub pg_auth_type: AuthType,
     pub http_auth_type: AuthType,
-
-    pub(crate) virtual_file_io_engine: Option<String>,
-    pub(crate) get_vectored_impl: Option<String>,
-    pub(crate) get_impl: Option<String>,
-    pub(crate) validate_vectored_get: Option<bool>,
 }
 
 impl Default for PageServerConf {
@@ -169,10 +209,40 @@ impl Default for PageServerConf {
             listen_http_addr: String::new(),
             pg_auth_type: AuthType::Trust,
             http_auth_type: AuthType::Trust,
-            virtual_file_io_engine: None,
-            get_vectored_impl: None,
-            get_impl: None,
-            validate_vectored_get: None,
+        }
+    }
+}
+
+/// The toml that can be passed to `neon_local init --config`.
+/// This is a subset of the `pageserver.toml` configuration.
+// TODO(christian): use pageserver_api::config::ConfigToml (PR #7656)
+#[derive(Clone, Debug, serde::Deserialize, serde::Serialize)]
+pub struct NeonLocalInitPageserverConf {
+    pub id: NodeId,
+    pub listen_pg_addr: String,
+    pub listen_http_addr: String,
+    pub pg_auth_type: AuthType,
+    pub http_auth_type: AuthType,
+    #[serde(flatten)]
+    pub other: HashMap<String, toml::Value>,
+}
+
+impl From<&NeonLocalInitPageserverConf> for PageServerConf {
+    fn from(conf: &NeonLocalInitPageserverConf) -> Self {
+        let NeonLocalInitPageserverConf {
+            id,
+            listen_pg_addr,
+            listen_http_addr,
+            pg_auth_type,
+            http_auth_type,
+            other: _,
+        } = conf;
+        Self {
+            id: *id,
+            listen_pg_addr: listen_pg_addr.clone(),
+            listen_http_addr: listen_http_addr.clone(),
+            pg_auth_type: *pg_auth_type,
+            http_auth_type: *http_auth_type,
         }
     }
 }
@@ -360,41 +430,7 @@ impl LocalEnv {
             .collect()
     }
 
-    /// Create a LocalEnv from a config file.
-    ///
-    /// Unlike 'load_config', this function fills in any defaults that are missing
-    /// from the config file.
-    pub fn parse_config(toml: &str) -> anyhow::Result<Self> {
-        let mut env: LocalEnv = toml::from_str(toml)?;
-
-        // Find postgres binaries.
-        // Follow POSTGRES_DISTRIB_DIR if set, otherwise look in "pg_install".
-        // Note that later in the code we assume, that distrib dirs follow the same pattern
-        // for all postgres versions.
-        if env.pg_distrib_dir == Path::new("") {
-            if let Some(postgres_bin) = env::var_os("POSTGRES_DISTRIB_DIR") {
-                env.pg_distrib_dir = postgres_bin.into();
-            } else {
-                let cwd = env::current_dir()?;
-                env.pg_distrib_dir = cwd.join("pg_install")
-            }
-        }
-
-        // Find neon binaries.
-        if env.neon_distrib_dir == Path::new("") {
-            env.neon_distrib_dir = env::current_exe()?.parent().unwrap().to_owned();
-        }
-
-        if env.pageservers.is_empty() {
-            anyhow::bail!("Configuration must contain at least one pageserver");
-        }
-
-        env.base_data_dir = base_path();
-
-        Ok(env)
-    }
-
-    /// Locate and load config
+    ///  Construct `Self` from on-disk state.
     pub fn load_config() -> anyhow::Result<Self> {
         let repopath = base_path();
 
@@ -408,38 +444,129 @@ impl LocalEnv {
         // TODO: check that it looks like a neon repository
 
         // load and parse file
-        let config = fs::read_to_string(repopath.join("config"))?;
-        let mut env: LocalEnv = toml::from_str(config.as_str())?;
+        let config_file_contents = fs::read_to_string(repopath.join("config"))?;
+        let on_disk_config: OnDiskConfig = toml::from_str(config_file_contents.as_str())?;
+        let mut env = {
+            let OnDiskConfig {
+                pg_distrib_dir,
+                neon_distrib_dir,
+                default_tenant_id,
+                private_key_path,
+                broker,
+                storage_controller,
+                pageservers,
+                safekeepers,
+                control_plane_api,
+                control_plane_compute_hook_api,
+                branch_name_mappings,
+            } = on_disk_config;
+            LocalEnv {
+                base_data_dir: repopath.clone(),
+                pg_distrib_dir,
+                neon_distrib_dir,
+                default_tenant_id,
+                private_key_path,
+                broker,
+                storage_controller,
+                pageservers,
+                safekeepers,
+                control_plane_api,
+                control_plane_compute_hook_api,
+                branch_name_mappings,
+            }
+        };
 
-        env.base_data_dir = repopath;
+        // The source of truth for pageserver configuration is the pageserver.toml.
+        assert!(
+            env.pageservers.is_empty(),
+            "we ensure this during deserialization"
+        );
+        env.pageservers = {
+            let iter = std::fs::read_dir(&repopath).context("open dir")?;
+            let mut pageservers = Vec::new();
+            for res in iter {
+                let dentry = res?;
+                const PREFIX: &str = "pageserver_";
+                let dentry_name = dentry
+                    .file_name()
+                    .into_string()
+                    .ok()
+                    .with_context(|| format!("non-utf8 dentry: {:?}", dentry.path()))
+                    .unwrap();
+                if !dentry_name.starts_with(PREFIX) {
+                    continue;
+                }
+                if !dentry.file_type().context("determine file type")?.is_dir() {
+                    anyhow::bail!("expected a directory, got {:?}", dentry.path());
+                }
+                let id = dentry_name[PREFIX.len()..]
+                    .parse::<NodeId>()
+                    .with_context(|| format!("parse id from {:?}", dentry.path()))?;
+                // TODO(christian): use pageserver_api::config::ConfigToml (PR #7656)
+                #[derive(serde::Serialize, serde::Deserialize)]
+                // (allow unknown fields, unlike PageServerConf)
+                struct PageserverConfigTomlSubset {
+                    id: NodeId,
+                    listen_pg_addr: String,
+                    listen_http_addr: String,
+                    pg_auth_type: AuthType,
+                    http_auth_type: AuthType,
+                }
+                let config_toml_path = dentry.path().join("pageserver.toml");
+                let config_toml: PageserverConfigTomlSubset = toml_edit::de::from_str(
+                    &std::fs::read_to_string(&config_toml_path)
+                        .with_context(|| format!("read {:?}", config_toml_path))?,
+                )
+                .context("parse pageserver.toml")?;
+                let PageserverConfigTomlSubset {
+                    id: config_toml_id,
+                    listen_pg_addr,
+                    listen_http_addr,
+                    pg_auth_type,
+                    http_auth_type,
+                } = config_toml;
+                let conf = PageServerConf {
+                    id: {
+                        anyhow::ensure!(
+                            config_toml_id == id,
+                            "id mismatch: config_toml.id={config_toml_id} id={id}",
+                        );
+                        id
+                    },
+                    listen_pg_addr,
+                    listen_http_addr,
+                    pg_auth_type,
+                    http_auth_type,
+                };
+                pageservers.push(conf);
+            }
+            pageservers
+        };
 
         Ok(env)
     }
 
-    pub fn persist_config(&self, base_path: &Path) -> anyhow::Result<()> {
-        // Currently, the user first passes a config file with 'neon_local init --config=<path>'
-        // We read that in, in `create_config`, and fill any missing defaults. Then it's saved
-        // to .neon/config. TODO: We lose any formatting and comments along the way, which is
-        // a bit sad.
-        let mut conf_content = r#"# This file describes a local deployment of the page server
-# and safekeeeper node. It is read by the 'neon_local' command-line
-# utility.
-"#
-        .to_string();
-
-        // Convert the LocalEnv to a toml file.
-        //
-        // This could be as simple as this:
-        //
-        // conf_content += &toml::to_string_pretty(env)?;
-        //
-        // But it results in a "values must be emitted before tables". I'm not sure
-        // why, AFAICS the table, i.e. 'safekeepers: Vec<SafekeeperConf>' is last.
-        // Maybe rust reorders the fields to squeeze avoid padding or something?
-        // In any case, converting to toml::Value first, and serializing that, works.
-        // See https://github.com/alexcrichton/toml-rs/issues/142
-        conf_content += &toml::to_string_pretty(&toml::Value::try_from(self)?)?;
+    pub fn persist_config(&self) -> anyhow::Result<()> {
+        Self::persist_config_impl(
+            &self.base_data_dir,
+            &OnDiskConfig {
+                pg_distrib_dir: self.pg_distrib_dir.clone(),
+                neon_distrib_dir: self.neon_distrib_dir.clone(),
+                default_tenant_id: self.default_tenant_id,
+                private_key_path: self.private_key_path.clone(),
+                broker: self.broker.clone(),
+                storage_controller: self.storage_controller.clone(),
+                pageservers: vec![], // it's skip_serializing anyway
+                safekeepers: self.safekeepers.clone(),
+                control_plane_api: self.control_plane_api.clone(),
+                control_plane_compute_hook_api: self.control_plane_compute_hook_api.clone(),
+                branch_name_mappings: self.branch_name_mappings.clone(),
+            },
+        )
+    }
 
+    pub fn persist_config_impl(base_path: &Path, config: &OnDiskConfig) -> anyhow::Result<()> {
+        let conf_content = &toml::to_string_pretty(config)?;
         let target_config_path = base_path.join("config");
         fs::write(&target_config_path, conf_content).with_context(|| {
             format!(
@@ -464,17 +591,13 @@ impl LocalEnv {
         }
     }
 
-    //
-    // Initialize a new Neon repository
-    //
-    pub fn init(&mut self, pg_version: u32, force: &InitForceMode) -> anyhow::Result<()> {
-        // check if config already exists
-        let base_path = &self.base_data_dir;
-        ensure!(
-            base_path != Path::new(""),
-            "repository base path is missing"
-        );
+    /// Materialize the [`NeonLocalInitConf`] to disk. Called during [`neon_local init`].
+    pub fn init(conf: NeonLocalInitConf, force: &InitForceMode) -> anyhow::Result<()> {
+        let base_path = base_path();
+        assert_ne!(base_path, Path::new(""));
+        let base_path = &base_path;
 
+        // create base_path dir
         if base_path.exists() {
             match force {
                 InitForceMode::MustNotExist => {
@@ -506,70 +629,96 @@ impl LocalEnv {
                 }
             }
         }
-
-        if !self.pg_bin_dir(pg_version)?.join("postgres").exists() {
-            bail!(
-                "Can't find postgres binary at {}",
-                self.pg_bin_dir(pg_version)?.display()
-            );
-        }
-        for binary in ["pageserver", "safekeeper"] {
-            if !self.neon_distrib_dir.join(binary).exists() {
-                bail!(
-                    "Can't find binary '{binary}' in neon distrib dir '{}'",
-                    self.neon_distrib_dir.display()
-                );
-            }
-        }
-
         if !base_path.exists() {
             fs::create_dir(base_path)?;
         }
 
+        let NeonLocalInitConf {
+            pg_distrib_dir,
+            neon_distrib_dir,
+            default_tenant_id,
+            broker,
+            storage_controller,
+            pageservers,
+            safekeepers,
+            control_plane_api,
+            control_plane_compute_hook_api,
+        } = conf;
+
+        // Find postgres binaries.
+        // Follow POSTGRES_DISTRIB_DIR if set, otherwise look in "pg_install".
+        // Note that later in the code we assume, that distrib dirs follow the same pattern
+        // for all postgres versions.
+        let pg_distrib_dir = pg_distrib_dir.unwrap_or_else(|| {
+            if let Some(postgres_bin) = env::var_os("POSTGRES_DISTRIB_DIR") {
+                postgres_bin.into()
+            } else {
+                let cwd = env::current_dir().unwrap();
+                cwd.join("pg_install")
+            }
+        });
+
+        // Find neon binaries.
+        let neon_distrib_dir = neon_distrib_dir
+            .unwrap_or_else(|| env::current_exe().unwrap().parent().unwrap().to_owned());
+
         // Generate keypair for JWT.
         //
         // The keypair is only needed if authentication is enabled in any of the
         // components. For convenience, we generate the keypair even if authentication
         // is not enabled, so that you can easily enable it after the initialization
-        // step. However, if the key generation fails, we treat it as non-fatal if
-        // authentication was not enabled.
-        if self.private_key_path == PathBuf::new() {
-            match generate_auth_keys(
-                base_path.join("auth_private_key.pem").as_path(),
-                base_path.join("auth_public_key.pem").as_path(),
-            ) {
-                Ok(()) => {
-                    self.private_key_path = PathBuf::from("auth_private_key.pem");
-                }
-                Err(e) => {
-                    if !self.auth_keys_needed() {
-                        eprintln!("Could not generate keypair for JWT authentication: {e}");
-                        eprintln!("Continuing anyway because authentication was not enabled");
-                        self.private_key_path = PathBuf::from("auth_private_key.pem");
-                    } else {
-                        return Err(e);
-                    }
-                }
-            }
+        // step.
+        generate_auth_keys(
+            base_path.join("auth_private_key.pem").as_path(),
+            base_path.join("auth_public_key.pem").as_path(),
+        )
+        .context("generate auth keys")?;
+        let private_key_path = PathBuf::from("auth_private_key.pem");
+
+        // create the runtime type because the remaining initialization code below needs
+        // a LocalEnv instance op operation
+        // TODO: refactor to avoid this, LocalEnv should only be constructed from on-disk state
+        let env = LocalEnv {
+            base_data_dir: base_path.clone(),
+            pg_distrib_dir,
+            neon_distrib_dir,
+            default_tenant_id: Some(default_tenant_id),
+            private_key_path,
+            broker,
+            storage_controller: storage_controller.unwrap_or_default(),
+            pageservers: pageservers.iter().map(Into::into).collect(),
+            safekeepers,
+            control_plane_api: control_plane_api.unwrap_or_default(),
+            control_plane_compute_hook_api: control_plane_compute_hook_api.unwrap_or_default(),
+            branch_name_mappings: Default::default(),
+        };
+
+        // create endpoints dir
+        fs::create_dir_all(env.endpoints_path())?;
+
+        // create safekeeper dirs
+        for safekeeper in &env.safekeepers {
+            fs::create_dir_all(SafekeeperNode::datadir_path_by_id(&env, safekeeper.id))?;
         }
 
-        fs::create_dir_all(self.endpoints_path())?;
-
-        for safekeeper in &self.safekeepers {
-            fs::create_dir_all(SafekeeperNode::datadir_path_by_id(self, safekeeper.id))?;
+        // initialize pageserver state
+        for (i, ps) in pageservers.into_iter().enumerate() {
+            let runtime_ps = &env.pageservers[i];
+            assert_eq!(&PageServerConf::from(&ps), runtime_ps);
+            fs::create_dir(env.pageserver_data_dir(ps.id))?;
+            PageServerNode::from_env(&env, runtime_ps)
+                .initialize(ps)
+                .context("pageserver init failed")?;
         }
 
-        self.persist_config(base_path)
-    }
+        // setup remote remote location for default LocalFs remote storage
+        std::fs::create_dir_all(env.base_data_dir.join(PAGESERVER_REMOTE_STORAGE_DIR))?;
 
-    fn auth_keys_needed(&self) -> bool {
-        self.pageservers.iter().any(|ps| {
-            ps.pg_auth_type == AuthType::NeonJWT || ps.http_auth_type == AuthType::NeonJWT
-        }) || self.safekeepers.iter().any(|sk| sk.auth_enabled)
+        env.persist_config()
     }
 }
 
-fn base_path() -> PathBuf {
+pub fn base_path() -> PathBuf {
     match std::env::var_os("NEON_REPO_DIR") {
         Some(val) => PathBuf::from(val),
         None => PathBuf::from(".neon"),
@@ -612,31 +761,3 @@ fn generate_auth_keys(private_key_path: &Path, public_key_path: &Path) -> anyhow
     }
     Ok(())
 }
-
-#[cfg(test)]
-mod tests {
-    use super::*;
-
-    #[test]
-    fn simple_conf_parsing() {
-        let simple_conf_toml = include_str!("../simple.conf");
-        let simple_conf_parse_result = LocalEnv::parse_config(simple_conf_toml);
-        assert!(
-            simple_conf_parse_result.is_ok(),
-            "failed to parse simple config {simple_conf_toml}, reason: {simple_conf_parse_result:?}"
-        );
-
-        let string_to_replace = "listen_addr = '127.0.0.1:50051'";
-        let spoiled_url_str = "listen_addr = '!@$XOXO%^&'";
-        let spoiled_url_toml = simple_conf_toml.replace(string_to_replace, spoiled_url_str);
-        assert!(
-            spoiled_url_toml.contains(spoiled_url_str),
-            "Failed to replace string {string_to_replace} in the toml file {simple_conf_toml}"
-        );
-        let spoiled_url_parse_result = LocalEnv::parse_config(&spoiled_url_toml);
-        assert!(
-            spoiled_url_parse_result.is_err(),
-            "expected toml with invalid Url {spoiled_url_toml} to fail the parsing, but got {spoiled_url_parse_result:?}"
-        );
-    }
-}

control_plane/src/pageserver.rs

@@ -4,21 +4,21 @@
 //!
 //!   .neon/
 //!
-use std::borrow::Cow;
 use std::collections::HashMap;
 
 use std::io;
 use std::io::Write;
 use std::num::NonZeroU64;
 use std::path::PathBuf;
-use std::process::Command;
+use std::str::FromStr;
 use std::time::Duration;
 
 use anyhow::{bail, Context};
 use camino::Utf8PathBuf;
 use futures::SinkExt;
 use pageserver_api::models::{
-    self, LocationConfig, ShardParameters, TenantHistorySize, TenantInfo, TimelineInfo,
+    self, AuxFilePolicy, LocationConfig, ShardParameters, TenantHistorySize, TenantInfo,
+    TimelineInfo,
 };
 use pageserver_api::shard::TenantShardId;
 use pageserver_client::mgmt_api;
@@ -30,7 +30,7 @@ use utils::{
     lsn::Lsn,
 };
 
-use crate::local_env::PageServerConf;
+use crate::local_env::{NeonLocalInitPageserverConf, PageServerConf};
 use crate::{background_process, local_env::LocalEnv};
 
 /// Directory within .neon which will be used by default for LocalFs remote storage.
@@ -74,71 +74,23 @@ impl PageServerNode {
         }
     }
 
-    /// Merge overrides provided by the user on the command line with our default overides derived from neon_local configuration.
-    ///
-    /// These all end up on the command line of the `pageserver` binary.
-    fn neon_local_overrides(&self, cli_overrides: &[&str]) -> Vec<String> {
+    fn pageserver_init_make_toml(
+        &self,
+        conf: NeonLocalInitPageserverConf,
+    ) -> anyhow::Result<toml_edit::Document> {
+        assert_eq!(&PageServerConf::from(&conf), &self.conf, "during neon_local init, we derive the runtime state of ps conf (self.conf) from the --config flag fully");
+
+        // TODO(christian): instead of what we do here, create a pageserver_api::config::ConfigToml (PR #7656)
+
         // FIXME: the paths should be shell-escaped to handle paths with spaces, quotas etc.
         let pg_distrib_dir_param = format!(
             "pg_distrib_dir='{}'",
             self.env.pg_distrib_dir_raw().display()
         );
 
-        let PageServerConf {
-            id,
-            listen_pg_addr,
-            listen_http_addr,
-            pg_auth_type,
-            http_auth_type,
-            virtual_file_io_engine,
-            get_vectored_impl,
-            get_impl,
-            validate_vectored_get,
-        } = &self.conf;
-
-        let id = format!("id={}", id);
-
-        let http_auth_type_param = format!("http_auth_type='{}'", http_auth_type);
-        let listen_http_addr_param = format!("listen_http_addr='{}'", listen_http_addr);
-
-        let pg_auth_type_param = format!("pg_auth_type='{}'", pg_auth_type);
-        let listen_pg_addr_param = format!("listen_pg_addr='{}'", listen_pg_addr);
-        let virtual_file_io_engine = if let Some(virtual_file_io_engine) = virtual_file_io_engine {
-            format!("virtual_file_io_engine='{virtual_file_io_engine}'")
-        } else {
-            String::new()
-        };
-        let get_vectored_impl = if let Some(get_vectored_impl) = get_vectored_impl {
-            format!("get_vectored_impl='{get_vectored_impl}'")
-        } else {
-            String::new()
-        };
-        let get_impl = if let Some(get_impl) = get_impl {
-            format!("get_impl='{get_impl}'")
-        } else {
-            String::new()
-        };
-        let validate_vectored_get = if let Some(validate_vectored_get) = validate_vectored_get {
-            format!("validate_vectored_get={validate_vectored_get}")
-        } else {
-            String::new()
-        };
-
         let broker_endpoint_param = format!("broker_endpoint='{}'", self.env.broker.client_url());
 
-        let mut overrides = vec![
-            id,
-            pg_distrib_dir_param,
-            http_auth_type_param,
-            pg_auth_type_param,
-            listen_http_addr_param,
-            listen_pg_addr_param,
-            broker_endpoint_param,
-            virtual_file_io_engine,
-            get_vectored_impl,
-            get_impl,
-            validate_vectored_get,
-        ];
+        let mut overrides = vec![pg_distrib_dir_param, broker_endpoint_param];
 
         if let Some(control_plane_api) = &self.env.control_plane_api {
             overrides.push(format!(
@@ -148,7 +100,7 @@ impl PageServerNode {
 
             // Storage controller uses the same auth as pageserver: if JWT is enabled
             // for us, we will also need it to talk to them.
-            if matches!(http_auth_type, AuthType::NeonJWT) {
+            if matches!(conf.http_auth_type, AuthType::NeonJWT) {
                 let jwt_token = self
                     .env
                     .generate_auth_token(&Claims::new(None, Scope::GenerationsApi))
@@ -157,31 +109,40 @@ impl PageServerNode {
             }
         }
 
-        if !cli_overrides
-            .iter()
-            .any(|c| c.starts_with("remote_storage"))
-        {
+        if !conf.other.contains_key("remote_storage") {
             overrides.push(format!(
                 "remote_storage={{local_path='../{PAGESERVER_REMOTE_STORAGE_DIR}'}}"
             ));
         }
 
-        if *http_auth_type != AuthType::Trust || *pg_auth_type != AuthType::Trust {
+        if conf.http_auth_type != AuthType::Trust || conf.pg_auth_type != AuthType::Trust {
             // Keys are generated in the toplevel repo dir, pageservers' workdirs
             // are one level below that, so refer to keys with ../
             overrides.push("auth_validation_public_key_path='../auth_public_key.pem'".to_owned());
         }
 
         // Apply the user-provided overrides
-        overrides.extend(cli_overrides.iter().map(|&c| c.to_owned()));
+        overrides.push(
+            toml_edit::ser::to_string_pretty(&conf)
+                .expect("we deserialized this from toml earlier"),
+        );
 
-        overrides
+        // Turn `overrides` into a toml document.
+        // TODO: above code is legacy code, it should be refactored to use toml_edit directly.
+        let mut config_toml = toml_edit::Document::new();
+        for fragment_str in overrides {
+            let fragment = toml_edit::Document::from_str(&fragment_str)
+                .expect("all fragments in `overrides` are valid toml documents, this function controls that");
+            for (key, item) in fragment.iter() {
+                config_toml.insert(key, item.clone());
+            }
+        }
+        Ok(config_toml)
     }
 
     /// Initializes a pageserver node by creating its config with the overrides provided.
-    pub fn initialize(&self, config_overrides: &[&str]) -> anyhow::Result<()> {
-        // First, run `pageserver --init` and wait for it to write a config into FS and exit.
-        self.pageserver_init(config_overrides)
+    pub fn initialize(&self, conf: NeonLocalInitPageserverConf) -> anyhow::Result<()> {
+        self.pageserver_init(conf)
             .with_context(|| format!("Failed to run init for pageserver node {}", self.conf.id))
     }
 
@@ -197,11 +158,11 @@ impl PageServerNode {
             .expect("non-Unicode path")
     }
 
-    pub async fn start(&self, config_overrides: &[&str]) -> anyhow::Result<()> {
-        self.start_node(config_overrides, false).await
+    pub async fn start(&self) -> anyhow::Result<()> {
+        self.start_node().await
     }
 
-    fn pageserver_init(&self, config_overrides: &[&str]) -> anyhow::Result<()> {
+    fn pageserver_init(&self, conf: NeonLocalInitPageserverConf) -> anyhow::Result<()> {
         let datadir = self.repo_path();
         let node_id = self.conf.id;
         println!(
@@ -212,29 +173,20 @@ impl PageServerNode {
         );
         io::stdout().flush()?;
 
-        if !datadir.exists() {
-            std::fs::create_dir(&datadir)?;
-        }
-
-        let datadir_path_str = datadir.to_str().with_context(|| {
-            format!("Cannot start pageserver node {node_id} in path that has no string representation: {datadir:?}")
-        })?;
-        let mut args = self.pageserver_basic_args(config_overrides, datadir_path_str);
-        args.push(Cow::Borrowed("--init"));
-
-        let init_output = Command::new(self.env.pageserver_bin())
-            .args(args.iter().map(Cow::as_ref))
-            .envs(self.pageserver_env_variables()?)
-            .output()
-            .with_context(|| format!("Failed to run pageserver init for node {node_id}"))?;
-
-        anyhow::ensure!(
-            init_output.status.success(),
-            "Pageserver init for node {} did not finish successfully, stdout: {}, stderr: {}",
-            node_id,
-            String::from_utf8_lossy(&init_output.stdout),
-            String::from_utf8_lossy(&init_output.stderr),
-        );
+        let config = self
+            .pageserver_init_make_toml(conf)
+            .context("make pageserver toml")?;
+        let config_file_path = datadir.join("pageserver.toml");
+        let mut config_file = std::fs::OpenOptions::new()
+            .create_new(true)
+            .write(true)
+            .open(&config_file_path)
+            .with_context(|| format!("open pageserver toml for write: {config_file_path:?}"))?;
+        config_file
+            .write_all(config.to_string().as_bytes())
+            .context("write pageserver toml")?;
+        drop(config_file);
+        // TODO: invoke a TBD config-check command to validate that pageserver will start with the written config
 
         // Write metadata file, used by pageserver on startup to register itself with
         // the storage controller
@@ -248,12 +200,13 @@ impl PageServerNode {
         // situation: the metadata is written by some other script.
         std::fs::write(
             metadata_path,
-            serde_json::to_vec(&serde_json::json!({
-                "host": "localhost",
-                "port": self.pg_connection_config.port(),
-                "http_host": "localhost",
-                "http_port": http_port,
-            }))
+            serde_json::to_vec(&pageserver_api::config::NodeMetadata {
+                postgres_host: "localhost".to_string(),
+                postgres_port: self.pg_connection_config.port(),
+                http_host: "localhost".to_string(),
+                http_port,
+                other: HashMap::new(),
+            })
             .unwrap(),
         )
         .expect("Failed to write metadata file");
@@ -261,11 +214,7 @@ impl PageServerNode {
         Ok(())
     }
 
-    async fn start_node(
-        &self,
-        config_overrides: &[&str],
-        update_config: bool,
-    ) -> anyhow::Result<()> {
+    async fn start_node(&self) -> anyhow::Result<()> {
         // TODO: using a thread here because start_process() is not async but we need to call check_status()
         let datadir = self.repo_path();
         print!(
@@ -282,15 +231,12 @@ impl PageServerNode {
                 self.conf.id, datadir,
             )
         })?;
-        let mut args = self.pageserver_basic_args(config_overrides, datadir_path_str);
-        if update_config {
-            args.push(Cow::Borrowed("--update-config"));
-        }
+        let args = vec!["-D", datadir_path_str];
         background_process::start_process(
             "pageserver",
             &datadir,
             &self.env.pageserver_bin(),
-            args.iter().map(Cow::as_ref),
+            args,
             self.pageserver_env_variables()?,
             background_process::InitialPidFile::Expect(self.pid_file()),
             || async {
@@ -307,22 +253,6 @@ impl PageServerNode {
         Ok(())
     }
 
-    fn pageserver_basic_args<'a>(
-        &self,
-        config_overrides: &'a [&'a str],
-        datadir_path_str: &'a str,
-    ) -> Vec<Cow<'a, str>> {
-        let mut args = vec![Cow::Borrowed("-D"), Cow::Borrowed(datadir_path_str)];
-
-        let overrides = self.neon_local_overrides(config_overrides);
-        for config_override in overrides {
-            args.push(Cow::Borrowed("-c"));
-            args.push(Cow::Owned(config_override));
-        }
-
-        args
-    }
-
     fn pageserver_env_variables(&self) -> anyhow::Result<Vec<(String, String)>> {
         // FIXME: why is this tied to pageserver's auth type? Whether or not the safekeeper
         // needs a token, and how to generate that token, seems independent to whether
@@ -448,11 +378,11 @@ impl PageServerNode {
                 .map(serde_json::from_str)
                 .transpose()
                 .context("parse `timeline_get_throttle` from json")?,
-            switch_to_aux_file_v2: settings
-                .remove("switch_to_aux_file_v2")
-                .map(|x| x.parse::<bool>())
+            switch_aux_file_policy: settings
+                .remove("switch_aux_file_policy")
+                .map(|x| x.parse::<AuxFilePolicy>())
                 .transpose()
-                .context("Failed to parse 'switch_to_aux_file_v2' as bool")?,
+                .context("Failed to parse 'switch_aux_file_policy'")?,
         };
         if !settings.is_empty() {
             bail!("Unrecognized tenant settings: {settings:?}")
@@ -571,11 +501,11 @@ impl PageServerNode {
                     .map(serde_json::from_str)
                     .transpose()
                     .context("parse `timeline_get_throttle` from json")?,
-                switch_to_aux_file_v2: settings
-                    .remove("switch_to_aux_file_v2")
-                    .map(|x| x.parse::<bool>())
+                switch_aux_file_policy: settings
+                    .remove("switch_aux_file_policy")
+                    .map(|x| x.parse::<AuxFilePolicy>())
                     .transpose()
-                    .context("Failed to parse 'switch_to_aux_file_v2' as bool")?,
+                    .context("Failed to parse 'switch_aux_file_policy'")?,
             }
         };
 

control_plane/src/storage_controller.rs

@@ -3,7 +3,6 @@ use crate::{
     local_env::{LocalEnv, NeonStorageControllerConf},
 };
 use camino::{Utf8Path, Utf8PathBuf};
-use hyper::Method;
 use pageserver_api::{
     controller_api::{
         NodeConfigureRequest, NodeRegisterRequest, TenantCreateResponse, TenantLocateResponse,
@@ -17,6 +16,7 @@ use pageserver_api::{
 };
 use pageserver_client::mgmt_api::ResponseErrorMessageExt;
 use postgres_backend::AuthType;
+use reqwest::Method;
 use serde::{de::DeserializeOwned, Deserialize, Serialize};
 use std::{fs, str::FromStr};
 use tokio::process::Command;
@@ -305,6 +305,10 @@ impl StorageController {
             ));
         }
 
+        if let Some(split_threshold) = self.config.split_threshold.as_ref() {
+            args.push(format!("--split-threshold={split_threshold}"))
+        }
+
         background_process::start_process(
             COMMAND,
             &self.env.base_data_dir,
@@ -379,7 +383,7 @@ impl StorageController {
     /// Simple HTTP request wrapper for calling into storage controller
     async fn dispatch<RQ, RS>(
         &self,
-        method: hyper::Method,
+        method: reqwest::Method,
         path: String,
         body: Option<RQ>,
     ) -> anyhow::Result<RS>

control_plane/storcon_cli/src/main.rs

@@ -1,7 +1,6 @@
 use std::{collections::HashMap, str::FromStr, time::Duration};
 
 use clap::{Parser, Subcommand};
-use hyper::{Method, StatusCode};
 use pageserver_api::{
     controller_api::{
         NodeAvailabilityWrapper, NodeDescribeResponse, ShardSchedulingPolicy,
@@ -14,7 +13,7 @@ use pageserver_api::{
     shard::{ShardStripeSize, TenantShardId},
 };
 use pageserver_client::mgmt_api::{self, ResponseErrorMessageExt};
-use reqwest::Url;
+use reqwest::{Method, StatusCode, Url};
 use serde::{de::DeserializeOwned, Serialize};
 use utils::id::{NodeId, TenantId};
 
@@ -232,7 +231,7 @@ impl Client {
     /// Simple HTTP request wrapper for calling into storage controller
     async fn dispatch<RQ, RS>(
         &self,
-        method: hyper::Method,
+        method: Method,
         path: String,
         body: Option<RQ>,
     ) -> mgmt_api::Result<RS>

libs/compute_api/src/responses.rs

@@ -3,7 +3,7 @@
 use chrono::{DateTime, Utc};
 use serde::{Deserialize, Serialize, Serializer};
 
-use crate::spec::ComputeSpec;
+use crate::spec::{ComputeSpec, Database, Role};
 
 #[derive(Serialize, Debug, Deserialize)]
 pub struct GenericAPIError {
@@ -113,6 +113,12 @@ pub struct ComputeMetrics {
     pub total_ext_download_size: u64,
 }
 
+#[derive(Clone, Debug, Default, Serialize)]
+pub struct CatalogObjects {
+    pub roles: Vec<Role>,
+    pub databases: Vec<Database>,
+}
+
 /// Response of the `/computes/{compute_id}/spec` control-plane API.
 /// This is not actually a compute API response, so consider moving
 /// to a different place.

libs/compute_api/src/spec.rs

@@ -33,6 +33,23 @@ pub struct ComputeSpec {
     #[serde(default)]
     pub features: Vec<ComputeFeature>,
 
+    /// If compute_ctl was passed `--resize-swap-on-bind`, a value of `Some(_)` instructs
+    /// compute_ctl to `/neonvm/bin/resize-swap` with the given size, when the spec is first
+    /// received.
+    ///
+    /// Both this field and `--resize-swap-on-bind` are required, so that the control plane's
+    /// spec generation doesn't need to be aware of the actual compute it's running on, while
+    /// guaranteeing gradual rollout of swap. Otherwise, without `--resize-swap-on-bind`, we could
+    /// end up trying to resize swap in VMs without it -- or end up *not* resizing swap, thus
+    /// giving every VM much more swap than it should have (32GiB).
+    ///
+    /// Eventually we may remove `--resize-swap-on-bind` and exclusively use `swap_size_bytes` for
+    /// enabling the swap resizing behavior once rollout is complete.
+    ///
+    /// See neondatabase/cloud#12047 for more.
+    #[serde(default)]
+    pub swap_size_bytes: Option<u64>,
+
     /// Expected cluster state at the end of transition process.
     pub cluster: Cluster,
     pub delta_operations: Option<Vec<DeltaOp>>,

libs/metrics/src/lib.rs

@@ -480,6 +480,15 @@ impl<A: CounterPairAssoc> CounterPairVec<A> {
         let id = self.vec.with_labels(labels);
         self.vec.remove_metric(id)
     }
+
+    pub fn sample(&self, labels: <A::LabelGroupSet as LabelGroupSet>::Group<'_>) -> u64 {
+        let id = self.vec.with_labels(labels);
+        let metric = self.vec.get_metric(id);
+
+        let inc = metric.inc.count.load(std::sync::atomic::Ordering::Relaxed);
+        let dec = metric.dec.count.load(std::sync::atomic::Ordering::Relaxed);
+        inc.saturating_sub(dec)
+    }
 }
 
 impl<T, A> ::measured::metric::group::MetricGroup<T> for CounterPairVec<A>

libs/pageserver_api/src/config.rs

@@ -0,0 +1,31 @@
+use std::collections::HashMap;
+
+use const_format::formatcp;
+
+#[cfg(test)]
+mod tests;
+
+pub const DEFAULT_PG_LISTEN_PORT: u16 = 64000;
+pub const DEFAULT_PG_LISTEN_ADDR: &str = formatcp!("127.0.0.1:{DEFAULT_PG_LISTEN_PORT}");
+pub const DEFAULT_HTTP_LISTEN_PORT: u16 = 9898;
+pub const DEFAULT_HTTP_LISTEN_ADDR: &str = formatcp!("127.0.0.1:{DEFAULT_HTTP_LISTEN_PORT}");
+
+// Certain metadata (e.g. externally-addressable name, AZ) is delivered
+// as a separate structure.  This information is not neeed by the pageserver
+// itself, it is only used for registering the pageserver with the control
+// plane and/or storage controller.
+//
+#[derive(PartialEq, Eq, Debug, serde::Serialize, serde::Deserialize)]
+pub struct NodeMetadata {
+    #[serde(rename = "host")]
+    pub postgres_host: String,
+    #[serde(rename = "port")]
+    pub postgres_port: u16,
+    pub http_host: String,
+    pub http_port: u16,
+
+    // Deployment tools may write fields to the metadata file beyond what we
+    // use in this type: this type intentionally only names fields that require.
+    #[serde(flatten)]
+    pub other: HashMap<String, serde_json::Value>,
+}

libs/pageserver_api/src/config/tests.rs

@@ -0,0 +1,22 @@
+use super::*;
+
+#[test]
+fn test_node_metadata_v1_backward_compatibilty() {
+    let v1 = serde_json::to_vec(&serde_json::json!({
+        "host": "localhost",
+        "port": 23,
+        "http_host": "localhost",
+        "http_port": 42,
+    }));
+
+    assert_eq!(
+        serde_json::from_slice::<NodeMetadata>(&v1.unwrap()).unwrap(),
+        NodeMetadata {
+            postgres_host: "localhost".to_string(),
+            postgres_port: 23,
+            http_host: "localhost".to_string(),
+            http_port: 42,
+            other: HashMap::new(),
+        }
+    )
+}

libs/pageserver_api/src/key.rs

@@ -80,7 +80,7 @@ impl Key {
     }
 
     /// Get the range of metadata keys.
-    pub fn metadata_key_range() -> Range<Self> {
+    pub const fn metadata_key_range() -> Range<Self> {
         Key {
             field1: METADATA_KEY_BEGIN_PREFIX,
             field2: 0,
@@ -572,14 +572,17 @@ pub const AUX_FILES_KEY: Key = Key {
 // Reverse mappings for a few Keys.
 // These are needed by WAL redo manager.
 
+/// Non inherited range for vectored get.
 pub const NON_INHERITED_RANGE: Range<Key> = AUX_FILES_KEY..AUX_FILES_KEY.next();
+/// Sparse keyspace range for vectored get. Missing key error will be ignored for this range.
+pub const NON_INHERITED_SPARSE_RANGE: Range<Key> = Key::metadata_key_range();
 
 // AUX_FILES currently stores only data for logical replication (slots etc), and
 // we don't preserve these on a branch because safekeepers can't follow timeline
 // switch (and generally it likely should be optional), so ignore these.
 #[inline(always)]
 pub fn is_inherited_key(key: Key) -> bool {
-    !NON_INHERITED_RANGE.contains(&key)
+    !NON_INHERITED_RANGE.contains(&key) && !NON_INHERITED_SPARSE_RANGE.contains(&key)
 }
 
 #[inline(always)]

libs/pageserver_api/src/keyspace.rs

@@ -240,7 +240,7 @@ impl<'a> ShardedRange<'a> {
     /// pages that would not actually be stored on this node.
     ///
     /// Don't use this function in code that works with physical entities like layer files.
-    fn raw_size(range: &Range<Key>) -> u32 {
+    pub fn raw_size(range: &Range<Key>) -> u32 {
         if is_contiguous_range(range) {
             contiguous_range_len(range)
         } else {

libs/pageserver_api/src/lib.rs

@@ -1,6 +1,5 @@
 #![deny(unsafe_code)]
 #![deny(clippy::undocumented_unsafe_blocks)]
-use const_format::formatcp;
 
 pub mod controller_api;
 pub mod key;
@@ -11,7 +10,4 @@ pub mod shard;
 /// Public API types
 pub mod upcall_api;
 
-pub const DEFAULT_PG_LISTEN_PORT: u16 = 64000;
-pub const DEFAULT_PG_LISTEN_ADDR: &str = formatcp!("127.0.0.1:{DEFAULT_PG_LISTEN_PORT}");
-pub const DEFAULT_HTTP_LISTEN_PORT: u16 = 9898;
-pub const DEFAULT_HTTP_LISTEN_ADDR: &str = formatcp!("127.0.0.1:{DEFAULT_HTTP_LISTEN_PORT}");
+pub mod config;

libs/pageserver_api/src/models.rs

@@ -1,3 +1,4 @@
+pub mod detach_ancestor;
 pub mod partitioning;
 pub mod utilization;
 
@@ -8,6 +9,8 @@ use std::{
     collections::HashMap,
     io::{BufRead, Read},
     num::{NonZeroU64, NonZeroUsize},
+    str::FromStr,
+    sync::atomic::AtomicUsize,
     time::{Duration, SystemTime},
 };
 
@@ -303,7 +306,106 @@ pub struct TenantConfig {
     pub lazy_slru_download: Option<bool>,
     pub timeline_get_throttle: Option<ThrottleConfig>,
     pub image_layer_creation_check_threshold: Option<u8>,
-    pub switch_to_aux_file_v2: Option<bool>,
+    pub switch_aux_file_policy: Option<AuxFilePolicy>,
+}
+
+/// The policy for the aux file storage. It can be switched through `switch_aux_file_policy`
+/// tenant config. When the first aux file written, the policy will be persisted in the
+/// `index_part.json` file and has a limited migration path.
+///
+/// Currently, we only allow the following migration path:
+///
+/// Unset -> V1
+///       -> V2
+///       -> CrossValidation -> V2
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
+pub enum AuxFilePolicy {
+    /// V1 aux file policy: store everything in AUX_FILE_KEY
+    V1,
+    /// V2 aux file policy: store in the AUX_FILE keyspace
+    V2,
+    /// Cross validation runs both formats on the write path and does validation
+    /// on the read path.
+    CrossValidation,
+}
+
+impl AuxFilePolicy {
+    pub fn is_valid_migration_path(from: Option<Self>, to: Self) -> bool {
+        matches!(
+            (from, to),
+            (None, _) | (Some(AuxFilePolicy::CrossValidation), AuxFilePolicy::V2)
+        )
+    }
+
+    /// If a tenant writes aux files without setting `switch_aux_policy`, this value will be used.
+    pub fn default_tenant_config() -> Self {
+        Self::V1
+    }
+}
+
+/// The aux file policy memory flag. Users can store `Option<AuxFilePolicy>` into this atomic flag. 0 == unspecified.
+pub struct AtomicAuxFilePolicy(AtomicUsize);
+
+impl AtomicAuxFilePolicy {
+    pub fn new(policy: Option<AuxFilePolicy>) -> Self {
+        Self(AtomicUsize::new(
+            policy.map(AuxFilePolicy::to_usize).unwrap_or_default(),
+        ))
+    }
+
+    pub fn load(&self) -> Option<AuxFilePolicy> {
+        match self.0.load(std::sync::atomic::Ordering::Acquire) {
+            0 => None,
+            other => Some(AuxFilePolicy::from_usize(other)),
+        }
+    }
+
+    pub fn store(&self, policy: Option<AuxFilePolicy>) {
+        self.0.store(
+            policy.map(AuxFilePolicy::to_usize).unwrap_or_default(),
+            std::sync::atomic::Ordering::Release,
+        );
+    }
+}
+
+impl AuxFilePolicy {
+    pub fn to_usize(self) -> usize {
+        match self {
+            Self::V1 => 1,
+            Self::CrossValidation => 2,
+            Self::V2 => 3,
+        }
+    }
+
+    pub fn try_from_usize(this: usize) -> Option<Self> {
+        match this {
+            1 => Some(Self::V1),
+            2 => Some(Self::CrossValidation),
+            3 => Some(Self::V2),
+            _ => None,
+        }
+    }
+
+    pub fn from_usize(this: usize) -> Self {
+        Self::try_from_usize(this).unwrap()
+    }
+}
+
+impl FromStr for AuxFilePolicy {
+    type Err = anyhow::Error;
+
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        let s = s.to_lowercase();
+        if s == "v1" {
+            Ok(Self::V1)
+        } else if s == "v2" {
+            Ok(Self::V2)
+        } else if s == "crossvalidation" || s == "cross_validation" {
+            Ok(Self::CrossValidation)
+        } else {
+            anyhow::bail!("cannot parse {} to aux file policy", s)
+        }
+    }
 }
 
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
@@ -430,8 +532,6 @@ pub struct StatusResponse {
 #[derive(Serialize, Deserialize, Debug)]
 #[serde(deny_unknown_fields)]
 pub struct TenantLocationConfigRequest {
-    #[serde(skip_serializing_if = "Option::is_none")]
-    pub tenant_id: Option<TenantShardId>,
     #[serde(flatten)]
     pub config: LocationConfig, // as we have a flattened field, we should reject all unknown fields in it
 }
@@ -580,6 +680,9 @@ pub struct TimelineInfo {
     pub state: TimelineState,
 
     pub walreceiver_status: String,
+
+    /// The last aux file policy being used on this timeline
+    pub last_aux_file_policy: Option<AuxFilePolicy>,
 }
 
 #[derive(Debug, Clone, Serialize, Deserialize)]
@@ -721,6 +824,16 @@ impl HistoricLayerInfo {
         };
         *field = value;
     }
+    pub fn layer_file_size(&self) -> u64 {
+        match self {
+            HistoricLayerInfo::Delta {
+                layer_file_size, ..
+            } => *layer_file_size,
+            HistoricLayerInfo::Image {
+                layer_file_size, ..
+            } => *layer_file_size,
+        }
+    }
 }
 
 #[derive(Debug, Serialize, Deserialize)]
@@ -728,6 +841,16 @@ pub struct DownloadRemoteLayersTaskSpawnRequest {
     pub max_concurrent_downloads: NonZeroUsize,
 }
 
+#[derive(Debug, Serialize, Deserialize)]
+pub struct IngestAuxFilesRequest {
+    pub aux_files: HashMap<String, String>,
+}
+
+#[derive(Debug, Serialize, Deserialize)]
+pub struct ListAuxFilesRequest {
+    pub lsn: Lsn,
+}
+
 #[derive(Debug, Serialize, Deserialize, Clone)]
 pub struct DownloadRemoteLayersTaskInfo {
     pub task_id: String,
@@ -752,9 +875,6 @@ pub struct TimelineGcRequest {
 #[derive(Debug, Clone, Serialize, Deserialize)]
 pub struct WalRedoManagerProcessStatus {
     pub pid: u32,
-    /// The strum-generated `into::<&'static str>()` for `pageserver::walredo::ProcessKind`.
-    /// `ProcessKind` are a transitory thing, so, they have no enum representation in `pageserver_api`.
-    pub kind: Cow<'static, str>,
 }
 
 #[derive(Debug, Clone, Serialize, Deserialize)]
@@ -793,6 +913,55 @@ pub struct TenantScanRemoteStorageResponse {
     pub shards: Vec<TenantScanRemoteStorageShard>,
 }
 
+#[derive(Serialize, Deserialize, Debug, Clone)]
+#[serde(rename_all = "snake_case")]
+pub enum TenantSorting {
+    ResidentSize,
+    MaxLogicalSize,
+}
+
+impl Default for TenantSorting {
+    fn default() -> Self {
+        Self::ResidentSize
+    }
+}
+
+#[derive(Serialize, Deserialize, Debug, Clone)]
+pub struct TopTenantShardsRequest {
+    // How would you like to sort the tenants?
+    pub order_by: TenantSorting,
+
+    // How many results?
+    pub limit: usize,
+
+    // Omit tenants with more than this many shards (e.g. if this is the max number of shards
+    // that the caller would ever split to)
+    pub where_shards_lt: Option<ShardCount>,
+
+    // Omit tenants where the ordering metric is less than this (this is an optimization to
+    // let us quickly exclude numerous tiny shards)
+    pub where_gt: Option<u64>,
+}
+
+#[derive(Serialize, Deserialize, Debug, PartialEq, Eq)]
+pub struct TopTenantShardItem {
+    pub id: TenantShardId,
+
+    /// Total size of layers on local disk for all timelines in this tenant
+    pub resident_size: u64,
+
+    /// Total size of layers in remote storage for all timelines in this tenant
+    pub physical_size: u64,
+
+    /// The largest logical size of a timeline within this tenant
+    pub max_logical_size: u64,
+}
+
+#[derive(Serialize, Deserialize, Debug, Default)]
+pub struct TopTenantShardsResponse {
+    pub shards: Vec<TopTenantShardItem>,
+}
+
 pub mod virtual_file {
     #[derive(
         Copy,
@@ -1425,4 +1594,59 @@ mod tests {
             assert_eq!(actual, expected, "example on {line}");
         }
     }
+
+    #[test]
+    fn test_aux_file_migration_path() {
+        assert!(AuxFilePolicy::is_valid_migration_path(
+            None,
+            AuxFilePolicy::V1
+        ));
+        assert!(AuxFilePolicy::is_valid_migration_path(
+            None,
+            AuxFilePolicy::V2
+        ));
+        assert!(AuxFilePolicy::is_valid_migration_path(
+            None,
+            AuxFilePolicy::CrossValidation
+        ));
+        // Self-migration is not a valid migration path, and the caller should handle it by itself.
+        assert!(!AuxFilePolicy::is_valid_migration_path(
+            Some(AuxFilePolicy::V1),
+            AuxFilePolicy::V1
+        ));
+        assert!(!AuxFilePolicy::is_valid_migration_path(
+            Some(AuxFilePolicy::V2),
+            AuxFilePolicy::V2
+        ));
+        assert!(!AuxFilePolicy::is_valid_migration_path(
+            Some(AuxFilePolicy::CrossValidation),
+            AuxFilePolicy::CrossValidation
+        ));
+        // Migrations not allowed
+        assert!(!AuxFilePolicy::is_valid_migration_path(
+            Some(AuxFilePolicy::CrossValidation),
+            AuxFilePolicy::V1
+        ));
+        assert!(!AuxFilePolicy::is_valid_migration_path(
+            Some(AuxFilePolicy::V1),
+            AuxFilePolicy::V2
+        ));
+        assert!(!AuxFilePolicy::is_valid_migration_path(
+            Some(AuxFilePolicy::V2),
+            AuxFilePolicy::V1
+        ));
+        assert!(!AuxFilePolicy::is_valid_migration_path(
+            Some(AuxFilePolicy::V2),
+            AuxFilePolicy::CrossValidation
+        ));
+        assert!(!AuxFilePolicy::is_valid_migration_path(
+            Some(AuxFilePolicy::V1),
+            AuxFilePolicy::CrossValidation
+        ));
+        // Migrations allowed
+        assert!(AuxFilePolicy::is_valid_migration_path(
+            Some(AuxFilePolicy::CrossValidation),
+            AuxFilePolicy::V2
+        ));
+    }
 }

libs/pageserver_api/src/models/detach_ancestor.rs

@@ -0,0 +1,6 @@
+use utils::id::TimelineId;
+
+#[derive(Default, serde::Serialize)]
+pub struct AncestorDetached {
+    pub reparented_timelines: Vec<TimelineId>,
+}

libs/pageserver_api/src/shard.rs

@@ -97,7 +97,7 @@ impl ShardCount {
 
     /// The internal value of a ShardCount may be zero, which means "1 shard, but use
     /// legacy format for TenantShardId that excludes the shard suffix", also known
-    /// as `TenantShardId::unsharded`.
+    /// as [`TenantShardId::unsharded`].
     ///
     /// This method returns the actual number of shards, i.e. if our internal value is
     /// zero, we return 1 (unsharded tenants have 1 shard).
@@ -116,14 +116,16 @@ impl ShardCount {
         self.0
     }
 
-    ///
+    /// Whether the `ShardCount` is for an unsharded tenant, so uses one shard but
+    /// uses the legacy format for `TenantShardId`. See also the documentation for
+    /// [`Self::count`].
     pub fn is_unsharded(&self) -> bool {
         self.0 == 0
     }
 
     /// `v` may be zero, or the number of shards in the tenant.  `v` is what
     /// [`Self::literal`] would return.
-    pub fn new(val: u8) -> Self {
+    pub const fn new(val: u8) -> Self {
         Self(val)
     }
 }

libs/postgres_ffi/src/xlog_utils.rs

@@ -331,7 +331,10 @@ impl CheckPoint {
     /// Returns 'true' if the XID was updated.
     pub fn update_next_xid(&mut self, xid: u32) -> bool {
         // nextXid should be greater than any XID in WAL, so increment provided XID and check for wraparround.
-        let mut new_xid = std::cmp::max(xid.wrapping_add(1), pg_constants::FIRST_NORMAL_TRANSACTION_ID);
+        let mut new_xid = std::cmp::max(
+            xid.wrapping_add(1),
+            pg_constants::FIRST_NORMAL_TRANSACTION_ID,
+        );
         // To reduce number of metadata checkpoints, we forward align XID on XID_CHECKPOINT_INTERVAL.
         // XID_CHECKPOINT_INTERVAL should not be larger than BLCKSZ*CLOG_XACTS_PER_BYTE
         new_xid =
@@ -367,8 +370,16 @@ pub fn generate_wal_segment(segno: u64, system_id: u64, lsn: Lsn) -> Result<Byte
     let seg_off = lsn.segment_offset(WAL_SEGMENT_SIZE);
 
     let first_page_only = seg_off < XLOG_BLCKSZ;
-    let (shdr_rem_len, infoflags) = if first_page_only {
-        (seg_off, pg_constants::XLP_FIRST_IS_CONTRECORD)
+    // If first records starts in the middle of the page, pretend in page header
+    // there is a fake record which ends where first real record starts. This
+    // makes pg_waldump etc happy.
+    let (shdr_rem_len, infoflags) = if first_page_only && seg_off > 0 {
+        assert!(seg_off >= XLOG_SIZE_OF_XLOG_LONG_PHD);
+        // xlp_rem_len doesn't include page header, hence the subtraction.
+        (
+            seg_off - XLOG_SIZE_OF_XLOG_LONG_PHD,
+            pg_constants::XLP_FIRST_IS_CONTRECORD,
+        )
     } else {
         (0, 0)
     };
@@ -397,20 +408,22 @@ pub fn generate_wal_segment(segno: u64, system_id: u64, lsn: Lsn) -> Result<Byte
 
     if !first_page_only {
         let block_offset = lsn.page_offset_in_segment(WAL_SEGMENT_SIZE) as usize;
+        // see comments above about XLP_FIRST_IS_CONTRECORD and xlp_rem_len.
+        let (xlp_rem_len, xlp_info) = if page_off > 0 {
+            assert!(page_off >= XLOG_SIZE_OF_XLOG_SHORT_PHD as u64);
+            (
+                (page_off - XLOG_SIZE_OF_XLOG_SHORT_PHD as u64) as u32,
+                pg_constants::XLP_FIRST_IS_CONTRECORD,
+            )
+        } else {
+            (0, 0)
+        };
         let header = XLogPageHeaderData {
             xlp_magic: XLOG_PAGE_MAGIC as u16,
-            xlp_info: if page_off >= pg_constants::SIZE_OF_PAGE_HEADER as u64 {
-                pg_constants::XLP_FIRST_IS_CONTRECORD
-            } else {
-                0
-            },
+            xlp_info,
             xlp_tli: PG_TLI,
             xlp_pageaddr: lsn.page_lsn().0,
-            xlp_rem_len: if page_off >= pg_constants::SIZE_OF_PAGE_HEADER as u64 {
-                page_off as u32
-            } else {
-                0u32
-            },
+            xlp_rem_len,
             ..Default::default() // Put 0 in padding fields.
         };
         let hdr_bytes = header.encode()?;

libs/remote_storage/Cargo.toml

@@ -38,6 +38,7 @@ azure_storage_blobs.workspace = true
 futures-util.workspace = true
 http-types.workspace = true
 itertools.workspace = true
+sync_wrapper = { workspace = true, features = ["futures"] }
 
 [dev-dependencies]
 camino-tempfile.workspace = true

libs/remote_storage/src/azure_blob.rs

@@ -3,6 +3,7 @@
 use std::borrow::Cow;
 use std::collections::HashMap;
 use std::env;
+use std::io;
 use std::num::NonZeroU32;
 use std::pin::Pin;
 use std::str::FromStr;
@@ -20,6 +21,7 @@ use azure_storage_blobs::blob::CopyStatus;
 use azure_storage_blobs::prelude::ClientBuilder;
 use azure_storage_blobs::{blob::operations::GetBlobBuilder, prelude::ContainerClient};
 use bytes::Bytes;
+use futures::future::Either;
 use futures::stream::Stream;
 use futures_util::StreamExt;
 use futures_util::TryStreamExt;
@@ -27,6 +29,7 @@ use http_types::{StatusCode, Url};
 use tokio_util::sync::CancellationToken;
 use tracing::debug;
 
+use crate::RemoteStorageActivity;
 use crate::{
     error::Cancelled, s3_bucket::RequestKind, AzureConfig, ConcurrencyLimiter, Download,
     DownloadError, Listing, ListingMode, RemotePath, RemoteStorage, StorageMetadata,
@@ -128,12 +131,12 @@ impl AzureBlobStorage {
         let kind = RequestKind::Get;
 
         let _permit = self.permit(kind, cancel).await?;
+        let cancel_or_timeout = crate::support::cancel_or_timeout(self.timeout, cancel.clone());
+        let cancel_or_timeout_ = crate::support::cancel_or_timeout(self.timeout, cancel.clone());
 
         let mut etag = None;
         let mut last_modified = None;
         let mut metadata = HashMap::new();
-        // TODO give proper streaming response instead of buffering into RAM
-        // https://github.com/neondatabase/neon/issues/5563
 
         let download = async {
             let response = builder
@@ -152,39 +155,46 @@ impl AzureBlobStorage {
                 Err(_elapsed) => Err(DownloadError::Timeout),
             });
 
-            let mut response = std::pin::pin!(response);
+            let mut response = Box::pin(response);
 
-            let mut bufs = Vec::new();
-            while let Some(part) = response.next().await {
-                let part = part?;
-                if etag.is_none() {
-                    etag = Some(part.blob.properties.etag);
-                }
-                if last_modified.is_none() {
-                    last_modified = Some(part.blob.properties.last_modified.into());
-                }
-                if let Some(blob_meta) = part.blob.metadata {
-                    metadata.extend(blob_meta.iter().map(|(k, v)| (k.to_owned(), v.to_owned())));
-                }
-                let data = part
-                    .data
-                    .collect()
-                    .await
-                    .map_err(|e| DownloadError::Other(e.into()))?;
-                bufs.push(data);
-            }
-
-            if bufs.is_empty() {
+            let Some(part) = response.next().await else {
                 return Err(DownloadError::Other(anyhow::anyhow!(
-                    "Azure GET response contained no buffers"
+                    "Azure GET response contained no response body"
                 )));
+            };
+            let part = part?;
+            if etag.is_none() {
+                etag = Some(part.blob.properties.etag);
             }
+            if last_modified.is_none() {
+                last_modified = Some(part.blob.properties.last_modified.into());
+            }
+            if let Some(blob_meta) = part.blob.metadata {
+                metadata.extend(blob_meta.iter().map(|(k, v)| (k.to_owned(), v.to_owned())));
+            }
+
             // unwrap safety: if these were None, bufs would be empty and we would have returned an error already
             let etag = etag.unwrap();
             let last_modified = last_modified.unwrap();
 
+            let tail_stream = response
+                .map(|part| match part {
+                    Ok(part) => Either::Left(part.data.map(|r| r.map_err(io::Error::other))),
+                    Err(e) => {
+                        Either::Right(futures::stream::once(async { Err(io::Error::other(e)) }))
+                    }
+                })
+                .flatten();
+            let stream = part
+                .data
+                .map(|r| r.map_err(io::Error::other))
+                .chain(sync_wrapper::SyncStream::new(tail_stream));
+            //.chain(SyncStream::from_pin(Box::pin(tail_stream)));
+
+            let download_stream = crate::support::DownloadStream::new(cancel_or_timeout_, stream);
+
             Ok(Download {
-                download_stream: Box::pin(futures::stream::iter(bufs.into_iter().map(Ok))),
+                download_stream: Box::pin(download_stream),
                 etag,
                 last_modified,
                 metadata: Some(StorageMetadata(metadata)),
@@ -193,7 +203,10 @@ impl AzureBlobStorage {
 
         tokio::select! {
             bufs = download => bufs,
-            _ = cancel.cancelled() => Err(DownloadError::Cancelled),
+            cancel_or_timeout = cancel_or_timeout => match cancel_or_timeout {
+                TimeoutOrCancel::Timeout => Err(DownloadError::Timeout),
+                TimeoutOrCancel::Cancel => Err(DownloadError::Cancelled),
+            },
         }
     }
 
@@ -513,6 +526,10 @@ impl RemoteStorage for AzureBlobStorage {
         // https://learn.microsoft.com/en-us/azure/storage/blobs/point-in-time-restore-overview
         Err(TimeTravelError::Unimplemented)
     }
+
+    fn activity(&self) -> RemoteStorageActivity {
+        self.concurrency_limiter.activity()
+    }
 }
 
 pin_project_lite::pin_project! {

libs/remote_storage/src/lib.rs

@@ -55,11 +55,11 @@ pub use error::{DownloadError, TimeTravelError, TimeoutOrCancel};
 /// ~3500 PUT/COPY/POST/DELETE or 5500 GET/HEAD S3 requests
 /// <https://aws.amazon.com/premiumsupport/knowledge-center/s3-request-limit-avoid-throttling/>
 pub const DEFAULT_REMOTE_STORAGE_S3_CONCURRENCY_LIMIT: usize = 100;
-/// We set this a little bit low as we currently buffer the entire file into RAM
+/// Set this limit analogously to the S3 limit
 ///
 /// Here, a limit of max 20k concurrent connections was noted.
 /// <https://learn.microsoft.com/en-us/answers/questions/1301863/is-there-any-limitation-to-concurrent-connections>
-pub const DEFAULT_REMOTE_STORAGE_AZURE_CONCURRENCY_LIMIT: usize = 30;
+pub const DEFAULT_REMOTE_STORAGE_AZURE_CONCURRENCY_LIMIT: usize = 100;
 /// No limits on the client side, which currenltly means 1000 for AWS S3.
 /// <https://docs.aws.amazon.com/AmazonS3/latest/API/API_ListObjectsV2.html#API_ListObjectsV2_RequestSyntax>
 pub const DEFAULT_MAX_KEYS_PER_LIST_RESPONSE: Option<i32> = None;
@@ -263,6 +263,17 @@ pub trait RemoteStorage: Send + Sync + 'static {
         done_if_after: SystemTime,
         cancel: &CancellationToken,
     ) -> Result<(), TimeTravelError>;
+
+    /// Query how busy we currently are: may be used by callers which wish to politely
+    /// back off if there are already a lot of operations underway.
+    fn activity(&self) -> RemoteStorageActivity;
+}
+
+pub struct RemoteStorageActivity {
+    pub read_available: usize,
+    pub read_total: usize,
+    pub write_available: usize,
+    pub write_total: usize,
 }
 
 /// DownloadStream is sensitive to the timeout and cancellation used with the original
@@ -444,6 +455,15 @@ impl<Other: RemoteStorage> GenericRemoteStorage<Arc<Other>> {
             }
         }
     }
+
+    pub fn activity(&self) -> RemoteStorageActivity {
+        match self {
+            Self::LocalFs(s) => s.activity(),
+            Self::AwsS3(s) => s.activity(),
+            Self::AzureBlob(s) => s.activity(),
+            Self::Unreliable(s) => s.activity(),
+        }
+    }
 }
 
 impl GenericRemoteStorage {
@@ -774,6 +794,9 @@ struct ConcurrencyLimiter {
     // The helps to ensure we don't exceed the thresholds.
     write: Arc<Semaphore>,
     read: Arc<Semaphore>,
+
+    write_total: usize,
+    read_total: usize,
 }
 
 impl ConcurrencyLimiter {
@@ -802,10 +825,21 @@ impl ConcurrencyLimiter {
         Arc::clone(self.for_kind(kind)).acquire_owned().await
     }
 
+    fn activity(&self) -> RemoteStorageActivity {
+        RemoteStorageActivity {
+            read_available: self.read.available_permits(),
+            read_total: self.read_total,
+            write_available: self.write.available_permits(),
+            write_total: self.write_total,
+        }
+    }
+
     fn new(limit: usize) -> ConcurrencyLimiter {
         Self {
             read: Arc::new(Semaphore::new(limit)),
             write: Arc::new(Semaphore::new(limit)),
+            read_total: limit,
+            write_total: limit,
         }
     }
 }

libs/remote_storage/src/local_fs.rs

@@ -23,8 +23,8 @@ use tokio_util::{io::ReaderStream, sync::CancellationToken};
 use utils::crashsafe::path_with_suffix_extension;
 
 use crate::{
-    Download, DownloadError, Listing, ListingMode, RemotePath, TimeTravelError, TimeoutOrCancel,
-    REMOTE_STORAGE_PREFIX_SEPARATOR,
+    Download, DownloadError, Listing, ListingMode, RemotePath, RemoteStorageActivity,
+    TimeTravelError, TimeoutOrCancel, REMOTE_STORAGE_PREFIX_SEPARATOR,
 };
 
 use super::{RemoteStorage, StorageMetadata};
@@ -605,6 +605,16 @@ impl RemoteStorage for LocalFs {
     ) -> Result<(), TimeTravelError> {
         Err(TimeTravelError::Unimplemented)
     }
+
+    fn activity(&self) -> RemoteStorageActivity {
+        // LocalFS has no concurrency limiting: give callers the impression that plenty of units are available
+        RemoteStorageActivity {
+            read_available: 16,
+            read_total: 16,
+            write_available: 16,
+            write_total: 16,
+        }
+    }
 }
 
 fn storage_metadata_path(original_path: &Utf8Path) -> Utf8PathBuf {

libs/remote_storage/src/s3_bucket.rs

@@ -27,7 +27,7 @@ use aws_config::{
 };
 use aws_credential_types::provider::SharedCredentialsProvider;
 use aws_sdk_s3::{
-    config::{AsyncSleep, Builder, IdentityCache, Region, SharedAsyncSleep},
+    config::{AsyncSleep, IdentityCache, Region, SharedAsyncSleep},
     error::SdkError,
     operation::get_object::GetObjectError,
     types::{Delete, DeleteMarkerEntry, ObjectIdentifier, ObjectVersion, StorageClass},
@@ -47,8 +47,8 @@ use utils::backoff;
 use super::StorageMetadata;
 use crate::{
     error::Cancelled, support::PermitCarrying, ConcurrencyLimiter, Download, DownloadError,
-    Listing, ListingMode, RemotePath, RemoteStorage, S3Config, TimeTravelError, TimeoutOrCancel,
-    MAX_KEYS_PER_DELETE, REMOTE_STORAGE_PREFIX_SEPARATOR,
+    Listing, ListingMode, RemotePath, RemoteStorage, RemoteStorageActivity, S3Config,
+    TimeTravelError, TimeoutOrCancel, MAX_KEYS_PER_DELETE, REMOTE_STORAGE_PREFIX_SEPARATOR,
 };
 
 pub(super) mod metrics;
@@ -75,13 +75,13 @@ struct GetObjectRequest {
 }
 impl S3Bucket {
     /// Creates the S3 storage, errors if incorrect AWS S3 configuration provided.
-    pub fn new(aws_config: &S3Config, timeout: Duration) -> anyhow::Result<Self> {
+    pub fn new(remote_storage_config: &S3Config, timeout: Duration) -> anyhow::Result<Self> {
         tracing::debug!(
             "Creating s3 remote storage for S3 bucket {}",
-            aws_config.bucket_name
+            remote_storage_config.bucket_name
         );
 
-        let region = Some(Region::new(aws_config.bucket_region.clone()));
+        let region = Some(Region::new(remote_storage_config.bucket_region.clone()));
 
         let provider_conf = ProviderConfig::without_region().with_region(region.clone());
 
@@ -113,6 +113,38 @@ impl S3Bucket {
         // AWS SDK requires us to specify how the RetryConfig should sleep when it wants to back off
         let sleep_impl: Arc<dyn AsyncSleep> = Arc::new(TokioSleep::new());
 
+        let sdk_config_loader: aws_config::ConfigLoader = aws_config::defaults(
+            #[allow(deprecated)] /* TODO: https://github.com/neondatabase/neon/issues/7665 */
+            BehaviorVersion::v2023_11_09(),
+        )
+        .region(region)
+        .identity_cache(IdentityCache::lazy().build())
+        .credentials_provider(SharedCredentialsProvider::new(credentials_provider))
+        .sleep_impl(SharedAsyncSleep::from(sleep_impl));
+
+        let sdk_config: aws_config::SdkConfig = std::thread::scope(|s| {
+            s.spawn(|| {
+                // TODO: make this function async.
+                tokio::runtime::Builder::new_current_thread()
+                    .enable_all()
+                    .build()
+                    .unwrap()
+                    .block_on(sdk_config_loader.load())
+            })
+            .join()
+            .unwrap()
+        });
+
+        let mut s3_config_builder = aws_sdk_s3::config::Builder::from(&sdk_config);
+
+        // Technically, the `remote_storage_config.endpoint` field only applies to S3 interactions.
+        // (In case we ever re-use the `sdk_config` for more than just the S3 client in the future)
+        if let Some(custom_endpoint) = remote_storage_config.endpoint.clone() {
+            s3_config_builder = s3_config_builder
+                .endpoint_url(custom_endpoint)
+                .force_path_style(true);
+        }
+
         // We do our own retries (see [`backoff::retry`]).  However, for the AWS SDK to enable rate limiting in response to throttling
         // responses (e.g. 429 on too many ListObjectsv2 requests), we must provide a retry config.  We set it to use at most one
         // attempt, and enable 'Adaptive' mode, which causes rate limiting to be enabled.
@@ -120,42 +152,36 @@ impl S3Bucket {
         retry_config
             .set_max_attempts(Some(1))
             .set_mode(Some(RetryMode::Adaptive));
+        s3_config_builder = s3_config_builder.retry_config(retry_config.build());
 
-        let mut config_builder = Builder::default()
-            .behavior_version(BehaviorVersion::v2023_11_09())
-            .region(region)
-            .identity_cache(IdentityCache::lazy().build())
-            .credentials_provider(SharedCredentialsProvider::new(credentials_provider))
-            .retry_config(retry_config.build())
-            .sleep_impl(SharedAsyncSleep::from(sleep_impl));
+        let s3_config = s3_config_builder.build();
+        let client = aws_sdk_s3::Client::from_conf(s3_config);
 
-        if let Some(custom_endpoint) = aws_config.endpoint.clone() {
-            config_builder = config_builder
-                .endpoint_url(custom_endpoint)
-                .force_path_style(true);
-        }
+        let prefix_in_bucket = remote_storage_config
+            .prefix_in_bucket
+            .as_deref()
+            .map(|prefix| {
+                let mut prefix = prefix;
+                while prefix.starts_with(REMOTE_STORAGE_PREFIX_SEPARATOR) {
+                    prefix = &prefix[1..]
+                }
 
-        let client = Client::from_conf(config_builder.build());
+                let mut prefix = prefix.to_string();
+                while prefix.ends_with(REMOTE_STORAGE_PREFIX_SEPARATOR) {
+                    prefix.pop();
+                }
+                prefix
+            });
 
-        let prefix_in_bucket = aws_config.prefix_in_bucket.as_deref().map(|prefix| {
-            let mut prefix = prefix;
-            while prefix.starts_with(REMOTE_STORAGE_PREFIX_SEPARATOR) {
-                prefix = &prefix[1..]
-            }
-
-            let mut prefix = prefix.to_string();
-            while prefix.ends_with(REMOTE_STORAGE_PREFIX_SEPARATOR) {
-                prefix.pop();
-            }
-            prefix
-        });
         Ok(Self {
             client,
-            bucket_name: aws_config.bucket_name.clone(),
-            max_keys_per_list_response: aws_config.max_keys_per_list_response,
+            bucket_name: remote_storage_config.bucket_name.clone(),
+            max_keys_per_list_response: remote_storage_config.max_keys_per_list_response,
             prefix_in_bucket,
-            concurrency_limiter: ConcurrencyLimiter::new(aws_config.concurrency_limit.get()),
-            upload_storage_class: aws_config.upload_storage_class.clone(),
+            concurrency_limiter: ConcurrencyLimiter::new(
+                remote_storage_config.concurrency_limit.get(),
+            ),
+            upload_storage_class: remote_storage_config.upload_storage_class.clone(),
             timeout,
         })
     }
@@ -949,6 +975,10 @@ impl RemoteStorage for S3Bucket {
         }
         Ok(())
     }
+
+    fn activity(&self) -> RemoteStorageActivity {
+        self.concurrency_limiter.activity()
+    }
 }
 
 /// On drop (cancellation) count towards [`metrics::BucketMetrics::cancelled_waits`].

libs/remote_storage/src/simulate_failures.rs

@@ -12,7 +12,7 @@ use tokio_util::sync::CancellationToken;
 
 use crate::{
     Download, DownloadError, GenericRemoteStorage, Listing, ListingMode, RemotePath, RemoteStorage,
-    StorageMetadata, TimeTravelError,
+    RemoteStorageActivity, StorageMetadata, TimeTravelError,
 };
 
 pub struct UnreliableWrapper {
@@ -213,4 +213,8 @@ impl RemoteStorage for UnreliableWrapper {
             .time_travel_recover(prefix, timestamp, done_if_after, cancel)
             .await
     }
+
+    fn activity(&self) -> RemoteStorageActivity {
+        self.inner.activity()
+    }
 }

libs/utils/src/poison.rs

@@ -3,7 +3,7 @@
 //!  # Example
 //!
 //!  ```
-//!  # tokio_test::block_on(async {
+//!  # tokio::runtime::Builder::new_current_thread().enable_all().build().unwrap().block_on(async {
 //!  use utils::poison::Poison;
 //!  use std::time::Duration;
 //!

libs/walproposer/src/api_bindings.rs

@@ -50,6 +50,14 @@ extern "C" fn get_flush_rec_ptr(wp: *mut WalProposer) -> XLogRecPtr {
     }
 }
 
+extern "C" fn update_donor(wp: *mut WalProposer, donor: *mut Safekeeper, donor_lsn: XLogRecPtr) {
+    unsafe {
+        let callback_data = (*(*wp).config).callback_data;
+        let api = callback_data as *mut Box<dyn ApiImpl>;
+        (*api).update_donor(&mut (*donor), donor_lsn)
+    }
+}
+
 extern "C" fn get_current_timestamp(wp: *mut WalProposer) -> TimestampTz {
     unsafe {
         let callback_data = (*(*wp).config).callback_data;
@@ -391,6 +399,7 @@ pub(crate) fn create_api() -> walproposer_api {
         get_shmem_state: Some(get_shmem_state),
         start_streaming: Some(start_streaming),
         get_flush_rec_ptr: Some(get_flush_rec_ptr),
+        update_donor: Some(update_donor),
         get_current_timestamp: Some(get_current_timestamp),
         conn_error_message: Some(conn_error_message),
         conn_status: Some(conn_status),
@@ -421,6 +430,32 @@ pub(crate) fn create_api() -> walproposer_api {
     }
 }
 
+pub fn empty_shmem() -> crate::bindings::WalproposerShmemState {
+    let empty_feedback = crate::bindings::PageserverFeedback {
+        present: false,
+        currentClusterSize: 0,
+        last_received_lsn: 0,
+        disk_consistent_lsn: 0,
+        remote_consistent_lsn: 0,
+        replytime: 0,
+        shard_number: 0,
+    };
+
+    crate::bindings::WalproposerShmemState {
+        propEpochStartLsn: crate::bindings::pg_atomic_uint64 { value: 0 },
+        donor_name: [0; 64],
+        donor_conninfo: [0; 1024],
+        donor_lsn: 0,
+        mutex: 0,
+        mineLastElectedTerm: crate::bindings::pg_atomic_uint64 { value: 0 },
+        backpressureThrottlingTime: crate::bindings::pg_atomic_uint64 { value: 0 },
+        currentClusterSize: crate::bindings::pg_atomic_uint64 { value: 0 },
+        shard_ps_feedback: [empty_feedback; 128],
+        num_shards: 0,
+        min_ps_feedback: empty_feedback,
+    }
+}
+
 impl std::fmt::Display for Level {
     fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
         write!(f, "{:?}", self)

libs/walproposer/src/walproposer.rs

@@ -1,8 +1,5 @@
 use std::ffi::CString;
 
-use postgres_ffi::WAL_SEGMENT_SIZE;
-use utils::{id::TenantTimelineId, lsn::Lsn};
-
 use crate::{
     api_bindings::{create_api, take_vec_u8, Level},
     bindings::{
@@ -10,6 +7,8 @@ use crate::{
         WalProposerCreate, WalProposerFree, WalProposerPoll, WalProposerStart,
     },
 };
+use postgres_ffi::WAL_SEGMENT_SIZE;
+use utils::{id::TenantTimelineId, lsn::Lsn};
 
 /// Rust high-level wrapper for C walproposer API. Many methods are not required
 /// for simple cases, hence todo!() in default implementations.
@@ -28,6 +27,10 @@ pub trait ApiImpl {
         todo!()
     }
 
+    fn update_donor(&self, _donor: &mut Safekeeper, _donor_lsn: u64) {
+        todo!()
+    }
+
     fn get_current_timestamp(&self) -> i64 {
         todo!()
     }
@@ -274,6 +277,7 @@ mod tests {
         sync::{atomic::AtomicUsize, mpsc::sync_channel},
     };
 
+    use std::cell::UnsafeCell;
     use utils::id::TenantTimelineId;
 
     use crate::{api_bindings::Level, bindings::NeonWALReadResult, walproposer::Wrapper};
@@ -297,6 +301,8 @@ mod tests {
         replies_ptr: AtomicUsize,
         // channel to send LSN to the main thread
         sync_channel: std::sync::mpsc::SyncSender<u64>,
+        // Shmem state, used for storing donor info
+        shmem: UnsafeCell<crate::bindings::WalproposerShmemState>,
     }
 
     impl MockImpl {
@@ -327,11 +333,22 @@ mod tests {
     }
 
     impl ApiImpl for MockImpl {
+        fn get_shmem_state(&self) -> *mut crate::bindings::WalproposerShmemState {
+            self.shmem.get()
+        }
+
         fn get_current_timestamp(&self) -> i64 {
             println!("get_current_timestamp");
             0
         }
 
+        fn update_donor(&self, donor: &mut crate::bindings::Safekeeper, donor_lsn: u64) {
+            let mut shmem = unsafe { *self.get_shmem_state() };
+            shmem.propEpochStartLsn.value = donor_lsn;
+            shmem.donor_conninfo = donor.conninfo;
+            shmem.donor_lsn = donor_lsn;
+        }
+
         fn conn_status(
             &self,
             _: &mut crate::bindings::Safekeeper,
@@ -507,6 +524,7 @@ mod tests {
             ],
             replies_ptr: AtomicUsize::new(0),
             sync_channel: sender,
+            shmem: UnsafeCell::new(crate::api_bindings::empty_shmem()),
         });
         let config = crate::walproposer::Config {
             ttid,

pageserver/benches/bench_layer_map.rs

@@ -1,7 +1,7 @@
 use pageserver::keyspace::{KeyPartitioning, KeySpace};
 use pageserver::repository::Key;
 use pageserver::tenant::layer_map::LayerMap;
-use pageserver::tenant::storage_layer::LayerFileName;
+use pageserver::tenant::storage_layer::LayerName;
 use pageserver::tenant::storage_layer::PersistentLayerDesc;
 use pageserver_api::shard::TenantShardId;
 use rand::prelude::{SeedableRng, SliceRandom, StdRng};
@@ -28,7 +28,7 @@ fn build_layer_map(filename_dump: PathBuf) -> LayerMap {
     let mut updates = layer_map.batch_update();
     for fname in filenames {
         let fname = fname.unwrap();
-        let fname = LayerFileName::from_str(&fname).unwrap();
+        let fname = LayerName::from_str(&fname).unwrap();
         let layer = PersistentLayerDesc::from(fname);
 
         let lsn_range = layer.get_lsn_range();

pageserver/benches/bench_walredo.rs

@@ -30,47 +30,27 @@
 //! 2024-04-15 on i3en.3xlarge
 //!
 //! ```text
-//! async-short/1           time:   [24.584 µs 24.737 µs 24.922 µs]
-//! async-short/2           time:   [33.479 µs 33.660 µs 33.888 µs]
-//! async-short/4           time:   [42.713 µs 43.046 µs 43.440 µs]
-//! async-short/8           time:   [71.814 µs 72.478 µs 73.240 µs]
-//! async-short/16          time:   [132.73 µs 134.45 µs 136.22 µs]
-//! async-short/32          time:   [258.31 µs 260.73 µs 263.27 µs]
-//! async-short/64          time:   [511.61 µs 514.44 µs 517.51 µs]
-//! async-short/128         time:   [992.64 µs 998.23 µs 1.0042 ms]
-//! async-medium/1          time:   [110.11 µs 110.50 µs 110.96 µs]
-//! async-medium/2          time:   [153.06 µs 153.85 µs 154.99 µs]
-//! async-medium/4          time:   [317.51 µs 319.92 µs 322.85 µs]
-//! async-medium/8          time:   [638.30 µs 644.68 µs 652.12 µs]
-//! async-medium/16         time:   [1.2651 ms 1.2773 ms 1.2914 ms]
-//! async-medium/32         time:   [2.5117 ms 2.5410 ms 2.5720 ms]
-//! async-medium/64         time:   [4.8088 ms 4.8555 ms 4.9047 ms]
-//! async-medium/128        time:   [8.8311 ms 8.9849 ms 9.1263 ms]
-//! sync-short/1            time:   [25.503 µs 25.626 µs 25.771 µs]
-//! sync-short/2            time:   [30.850 µs 31.013 µs 31.208 µs]
-//! sync-short/4            time:   [45.543 µs 45.856 µs 46.193 µs]
-//! sync-short/8            time:   [84.114 µs 84.639 µs 85.220 µs]
-//! sync-short/16           time:   [185.22 µs 186.15 µs 187.13 µs]
-//! sync-short/32           time:   [377.43 µs 378.87 µs 380.46 µs]
-//! sync-short/64           time:   [756.49 µs 759.04 µs 761.70 µs]
-//! sync-short/128          time:   [1.4825 ms 1.4874 ms 1.4923 ms]
-//! sync-medium/1           time:   [105.66 µs 106.01 µs 106.43 µs]
-//! sync-medium/2           time:   [153.10 µs 153.84 µs 154.72 µs]
-//! sync-medium/4           time:   [327.13 µs 329.44 µs 332.27 µs]
-//! sync-medium/8           time:   [654.26 µs 658.73 µs 663.63 µs]
-//! sync-medium/16          time:   [1.2682 ms 1.2748 ms 1.2816 ms]
-//! sync-medium/32          time:   [2.4456 ms 2.4595 ms 2.4731 ms]
-//! sync-medium/64          time:   [4.6523 ms 4.6890 ms 4.7256 ms]
-//! sync-medium/128         time:   [8.7215 ms 8.8323 ms 8.9344 ms]
+//! short/1           time:   [24.584 µs 24.737 µs 24.922 µs]
+//! short/2           time:   [33.479 µs 33.660 µs 33.888 µs]
+//! short/4           time:   [42.713 µs 43.046 µs 43.440 µs]
+//! short/8           time:   [71.814 µs 72.478 µs 73.240 µs]
+//! short/16          time:   [132.73 µs 134.45 µs 136.22 µs]
+//! short/32          time:   [258.31 µs 260.73 µs 263.27 µs]
+//! short/64          time:   [511.61 µs 514.44 µs 517.51 µs]
+//! short/128         time:   [992.64 µs 998.23 µs 1.0042 ms]
+//! medium/1          time:   [110.11 µs 110.50 µs 110.96 µs]
+//! medium/2          time:   [153.06 µs 153.85 µs 154.99 µs]
+//! medium/4          time:   [317.51 µs 319.92 µs 322.85 µs]
+//! medium/8          time:   [638.30 µs 644.68 µs 652.12 µs]
+//! medium/16         time:   [1.2651 ms 1.2773 ms 1.2914 ms]
+//! medium/32         time:   [2.5117 ms 2.5410 ms 2.5720 ms]
+//! medium/64         time:   [4.8088 ms 4.8555 ms 4.9047 ms]
+//! medium/128        time:   [8.8311 ms 8.9849 ms 9.1263 ms]
 //! ```
 
 use bytes::{Buf, Bytes};
 use criterion::{BenchmarkId, Criterion};
-use pageserver::{
-    config::PageServerConf,
-    walrecord::NeonWalRecord,
-    walredo::{PostgresRedoManager, ProcessKind},
-};
+use pageserver::{config::PageServerConf, walrecord::NeonWalRecord, walredo::PostgresRedoManager};
 use pageserver_api::{key::Key, shard::TenantShardId};
 use std::{
     sync::Arc,
@@ -80,39 +60,32 @@ use tokio::{sync::Barrier, task::JoinSet};
 use utils::{id::TenantId, lsn::Lsn};
 
 fn bench(c: &mut Criterion) {
-    for process_kind in &[ProcessKind::Async, ProcessKind::Sync] {
-        {
-            let nclients = [1, 2, 4, 8, 16, 32, 64, 128];
-            for nclients in nclients {
-                let mut group = c.benchmark_group(format!("{process_kind}-short"));
-                group.bench_with_input(
-                    BenchmarkId::from_parameter(nclients),
-                    &nclients,
-                    |b, nclients| {
-                        let redo_work = Arc::new(Request::short_input());
-                        b.iter_custom(|iters| {
-                            bench_impl(*process_kind, Arc::clone(&redo_work), iters, *nclients)
-                        });
-                    },
-                );
-            }
+    {
+        let nclients = [1, 2, 4, 8, 16, 32, 64, 128];
+        for nclients in nclients {
+            let mut group = c.benchmark_group("short");
+            group.bench_with_input(
+                BenchmarkId::from_parameter(nclients),
+                &nclients,
+                |b, nclients| {
+                    let redo_work = Arc::new(Request::short_input());
+                    b.iter_custom(|iters| bench_impl(Arc::clone(&redo_work), iters, *nclients));
+                },
+            );
         }
-
-        {
-            let nclients = [1, 2, 4, 8, 16, 32, 64, 128];
-            for nclients in nclients {
-                let mut group = c.benchmark_group(format!("{process_kind}-medium"));
-                group.bench_with_input(
-                    BenchmarkId::from_parameter(nclients),
-                    &nclients,
-                    |b, nclients| {
-                        let redo_work = Arc::new(Request::medium_input());
-                        b.iter_custom(|iters| {
-                            bench_impl(*process_kind, Arc::clone(&redo_work), iters, *nclients)
-                        });
-                    },
-                );
-            }
+    }
+    {
+        let nclients = [1, 2, 4, 8, 16, 32, 64, 128];
+        for nclients in nclients {
+            let mut group = c.benchmark_group("medium");
+            group.bench_with_input(
+                BenchmarkId::from_parameter(nclients),
+                &nclients,
+                |b, nclients| {
+                    let redo_work = Arc::new(Request::medium_input());
+                    b.iter_custom(|iters| bench_impl(Arc::clone(&redo_work), iters, *nclients));
+                },
+            );
         }
     }
 }
@@ -120,16 +93,10 @@ criterion::criterion_group!(benches, bench);
 criterion::criterion_main!(benches);
 
 // Returns the sum of each client's wall-clock time spent executing their share of the n_redos.
-fn bench_impl(
-    process_kind: ProcessKind,
-    redo_work: Arc<Request>,
-    n_redos: u64,
-    nclients: u64,
-) -> Duration {
+fn bench_impl(redo_work: Arc<Request>, n_redos: u64, nclients: u64) -> Duration {
     let repo_dir = camino_tempfile::tempdir_in(env!("CARGO_TARGET_TMPDIR")).unwrap();
 
-    let mut conf = PageServerConf::dummy_conf(repo_dir.path().to_path_buf());
-    conf.walredo_process_kind = process_kind;
+    let conf = PageServerConf::dummy_conf(repo_dir.path().to_path_buf());
     let conf = Box::leak(Box::new(conf));
     let tenant_shard_id = TenantShardId::unsharded(TenantId::generate());
 
@@ -158,27 +125,13 @@ fn bench_impl(
         });
     }
 
-    let elapsed = rt.block_on(async move {
+    rt.block_on(async move {
         let mut total_wallclock_time = Duration::ZERO;
         while let Some(res) = tasks.join_next().await {
             total_wallclock_time += res.unwrap();
         }
         total_wallclock_time
-    });
-
-    // consistency check to ensure process kind setting worked
-    if nredos_per_client > 0 {
-        assert_eq!(
-            manager
-                .status()
-                .process
-                .map(|p| p.kind)
-                .expect("the benchmark work causes a walredo process to be spawned"),
-            std::borrow::Cow::Borrowed(process_kind.into())
-        );
-    }
-
-    elapsed
+    })
 }
 
 async fn client(

pageserver/client/src/mgmt_api.rs

@@ -1,8 +1,12 @@
+use std::collections::HashMap;
+
+use bytes::Bytes;
 use pageserver_api::{models::*, shard::TenantShardId};
 use reqwest::{IntoUrl, Method, StatusCode};
 use utils::{
     http::error::HttpErrorBody,
     id::{TenantId, TimelineId},
+    lsn::Lsn,
 };
 
 pub mod util;
@@ -284,6 +288,34 @@ impl Client {
         Ok((status, progress))
     }
 
+    pub async fn tenant_secondary_status(
+        &self,
+        tenant_shard_id: TenantShardId,
+    ) -> Result<SecondaryProgress> {
+        let path = reqwest::Url::parse(&format!(
+            "{}/v1/tenant/{}/secondary/status",
+            self.mgmt_api_endpoint, tenant_shard_id
+        ))
+        .expect("Cannot build URL");
+
+        self.request(Method::GET, path, ())
+            .await?
+            .json()
+            .await
+            .map_err(Error::ReceiveBody)
+    }
+
+    pub async fn tenant_heatmap_upload(&self, tenant_id: TenantShardId) -> Result<()> {
+        let path = reqwest::Url::parse(&format!(
+            "{}/v1/tenant/{}/heatmap_upload",
+            self.mgmt_api_endpoint, tenant_id
+        ))
+        .expect("Cannot build URL");
+
+        self.request(Method::POST, path, ()).await?;
+        Ok(())
+    }
+
     pub async fn location_config(
         &self,
         tenant_shard_id: TenantShardId,
@@ -291,10 +323,7 @@ impl Client {
         flush_ms: Option<std::time::Duration>,
         lazy: bool,
     ) -> Result<()> {
-        let req_body = TenantLocationConfigRequest {
-            tenant_id: None,
-            config,
-        };
+        let req_body = TenantLocationConfigRequest { config };
 
         let mut path = reqwest::Url::parse(&format!(
             "{}/v1/tenant/{}/location_config",
@@ -461,6 +490,18 @@ impl Client {
             .map_err(Error::ReceiveBody)
     }
 
+    pub async fn top_tenant_shards(
+        &self,
+        request: TopTenantShardsRequest,
+    ) -> Result<TopTenantShardsResponse> {
+        let uri = format!("{}/v1/top_tenants", self.mgmt_api_endpoint);
+        self.request(Method::POST, uri, request)
+            .await?
+            .json()
+            .await
+            .map_err(Error::ReceiveBody)
+    }
+
     pub async fn layer_map_info(
         &self,
         tenant_shard_id: TenantShardId,
@@ -524,4 +565,57 @@ impl Client {
             }),
         }
     }
+
+    pub async fn ingest_aux_files(
+        &self,
+        tenant_shard_id: TenantShardId,
+        timeline_id: TimelineId,
+        aux_files: HashMap<String, String>,
+    ) -> Result<bool> {
+        let uri = format!(
+            "{}/v1/tenant/{}/timeline/{}/ingest_aux_files",
+            self.mgmt_api_endpoint, tenant_shard_id, timeline_id
+        );
+        let resp = self
+            .request_noerror(Method::POST, &uri, IngestAuxFilesRequest { aux_files })
+            .await?;
+        match resp.status() {
+            StatusCode::OK => Ok(true),
+            status => Err(match resp.json::<HttpErrorBody>().await {
+                Ok(HttpErrorBody { msg }) => Error::ApiError(status, msg),
+                Err(_) => {
+                    Error::ReceiveErrorBody(format!("Http error ({}) at {}.", status.as_u16(), uri))
+                }
+            }),
+        }
+    }
+
+    pub async fn list_aux_files(
+        &self,
+        tenant_shard_id: TenantShardId,
+        timeline_id: TimelineId,
+        lsn: Lsn,
+    ) -> Result<HashMap<String, Bytes>> {
+        let uri = format!(
+            "{}/v1/tenant/{}/timeline/{}/list_aux_files",
+            self.mgmt_api_endpoint, tenant_shard_id, timeline_id
+        );
+        let resp = self
+            .request_noerror(Method::POST, &uri, ListAuxFilesRequest { lsn })
+            .await?;
+        match resp.status() {
+            StatusCode::OK => {
+                let resp: HashMap<String, Bytes> = resp.json().await.map_err(|e| {
+                    Error::ApiError(StatusCode::INTERNAL_SERVER_ERROR, format!("{e}"))
+                })?;
+                Ok(resp)
+            }
+            status => Err(match resp.json::<HttpErrorBody>().await {
+                Ok(HttpErrorBody { msg }) => Error::ApiError(status, msg),
+                Err(_) => {
+                    Error::ReceiveErrorBody(format!("Http error ({}) at {}.", status.as_u16(), uri))
+                }
+            }),
+        }
+    }
 }

pageserver/compaction/src/bin/compaction-simulator.rs

@@ -1,4 +1,5 @@
 use clap::{Parser, Subcommand};
+use pageserver_compaction::helpers::PAGE_SZ;
 use pageserver_compaction::simulator::MockTimeline;
 use rand::Rng;
 use std::io::Write;
@@ -51,7 +52,7 @@ async fn simulate(cmd: &SimulateCmd, results_path: &Path) -> anyhow::Result<()>
     let mut executor = MockTimeline::new();
 
     // Convert the logical size in MB into a key range.
-    let key_range = 0..((cmd.logical_size * 1024 * 1024) / 8192);
+    let key_range = 0..((cmd.logical_size * 1024 * 1024) / PAGE_SZ);
     //let key_range = u64::MIN..u64::MAX;
     println!(
         "starting simulation with key range {:016X}-{:016X}",

pageserver/compaction/src/compact_tiered.rs

@@ -24,7 +24,9 @@ use tracing::{debug, info};
 use std::collections::{HashSet, VecDeque};
 use std::ops::Range;
 
-use crate::helpers::{accum_key_values, keyspace_total_size, merge_delta_keys, overlaps_with};
+use crate::helpers::{
+    accum_key_values, keyspace_total_size, merge_delta_keys_buffered, overlaps_with, PAGE_SZ,
+};
 use crate::interface::*;
 use utils::lsn::Lsn;
 
@@ -104,7 +106,13 @@ pub async fn compact_tiered<E: CompactionJobExecutor>(
             ctx,
         )
         .await?;
-        if target_file_size == u64::MAX {
+        if current_level_target_height == u64::MAX {
+            // our target height includes all possible lsns
+            info!(
+                level = current_level_no,
+                depth = depth,
+                "compaction loop reached max current_level_target_height"
+            );
             break;
         }
         current_level_no += 1;
@@ -371,7 +379,7 @@ where
                 .get_keyspace(&job.key_range, job.lsn_range.end, ctx)
                 .await?,
             &self.shard_identity,
-        ) * 8192;
+        ) * PAGE_SZ;
 
         let wal_size = job
             .input_layers
@@ -433,7 +441,7 @@ where
         let mut window = KeyspaceWindow::new(
             E::Key::MIN..E::Key::MAX,
             keyspace,
-            self.target_file_size / 8192,
+            self.target_file_size / PAGE_SZ,
         );
         while let Some(key_range) = window.choose_next_image(&self.shard_identity) {
             new_jobs.push(CompactionJob::<E> {
@@ -522,8 +530,6 @@ where
         // If we have accumulated only a narrow band of keyspace, create an
         // image layer. Otherwise write a delta layer.
 
-        // FIXME: deal with the case of lots of values for same key
-
         // FIXME: we are ignoring images here. Did we already divide the work
         // so that we won't encounter them here?
 
@@ -535,43 +541,101 @@ where
             }
         }
         // Open stream
-        let key_value_stream = std::pin::pin!(merge_delta_keys::<E>(deltas.as_slice(), ctx));
+        let key_value_stream =
+            std::pin::pin!(merge_delta_keys_buffered::<E>(deltas.as_slice(), ctx)
+                .await?
+                .map(Result::<_, anyhow::Error>::Ok));
         let mut new_jobs = Vec::new();
 
         // Slide a window through the keyspace
-        let mut key_accum = std::pin::pin!(accum_key_values(key_value_stream));
+        let mut key_accum =
+            std::pin::pin!(accum_key_values(key_value_stream, self.target_file_size));
         let mut all_in_window: bool = false;
         let mut window = Window::new();
+
+        // Helper function to create a job for a new delta layer with given key-lsn
+        // rectangle.
+        let create_delta_job = |key_range, lsn_range: &Range<Lsn>, new_jobs: &mut Vec<_>| {
+            // The inputs for the job are all the input layers of the original job that
+            // overlap with the rectangle.
+            let batch_layers: Vec<LayerId> = job
+                .input_layers
+                .iter()
+                .filter(|layer_id| {
+                    overlaps_with(self.layers[layer_id.0].layer.key_range(), &key_range)
+                })
+                .cloned()
+                .collect();
+            assert!(!batch_layers.is_empty());
+            new_jobs.push(CompactionJob {
+                key_range,
+                lsn_range: lsn_range.clone(),
+                strategy: CompactionStrategy::CreateDelta,
+                input_layers: batch_layers,
+                completed: false,
+            });
+        };
+
         loop {
-            if all_in_window && window.elems.is_empty() {
+            if all_in_window && window.is_empty() {
                 // All done!
                 break;
             }
+
+            // If we now have enough keyspace for next delta layer in the window, create a
+            // new delta layer
             if let Some(key_range) = window.choose_next_delta(self.target_file_size, !all_in_window)
             {
-                let batch_layers: Vec<LayerId> = job
-                    .input_layers
-                    .iter()
-                    .filter(|layer_id| {
-                        overlaps_with(self.layers[layer_id.0].layer.key_range(), &key_range)
-                    })
-                    .cloned()
-                    .collect();
-                assert!(!batch_layers.is_empty());
-                new_jobs.push(CompactionJob {
-                    key_range,
-                    lsn_range: job.lsn_range.clone(),
-                    strategy: CompactionStrategy::CreateDelta,
-                    input_layers: batch_layers,
-                    completed: false,
-                });
-            } else {
-                assert!(!all_in_window);
-                if let Some(next_key) = key_accum.next().await.transpose()? {
-                    window.feed(next_key.key, next_key.size);
-                } else {
+                create_delta_job(key_range, &job.lsn_range, &mut new_jobs);
+                continue;
+            }
+            assert!(!all_in_window);
+
+            // Process next key in the key space
+            match key_accum.next().await.transpose()? {
+                None => {
                     all_in_window = true;
                 }
+                Some(next_key) if next_key.partition_lsns.is_empty() => {
+                    // Normal case: extend the window by the key
+                    window.feed(next_key.key, next_key.size);
+                }
+                Some(next_key) => {
+                    // A key with too large size impact for a single delta layer. This
+                    // case occurs if you make a huge number of updates for a single key.
+                    //
+                    // Drain the window with has_more = false to make a clean cut before
+                    // the key, and then make dedicated delta layers for the single key.
+                    //
+                    // We cannot cluster the key with the others, because we don't want
+                    // layer files to overlap with each other in the lsn,key space (no
+                    // overlaps for the rectangles).
+                    let key = next_key.key;
+                    debug!("key {key} with size impact larger than the layer size");
+                    while !window.is_empty() {
+                        let has_more = false;
+                        let key_range = window.choose_next_delta(self.target_file_size, has_more)
+                            .expect("with has_more==false, choose_next_delta always returns something for a non-empty Window");
+                        create_delta_job(key_range, &job.lsn_range, &mut new_jobs);
+                    }
+
+                    // Not really required: but here for future resilience:
+                    // We make a "gap" here, so any structure the window holds should
+                    // probably be reset.
+                    window = Window::new();
+
+                    let mut prior_lsn = job.lsn_range.start;
+                    let mut lsn_ranges = Vec::new();
+                    for (lsn, _size) in next_key.partition_lsns.iter() {
+                        lsn_ranges.push(prior_lsn..*lsn);
+                        prior_lsn = *lsn;
+                    }
+                    lsn_ranges.push(prior_lsn..job.lsn_range.end);
+                    for lsn_range in lsn_ranges {
+                        let key_range = key..key.next();
+                        create_delta_job(key_range, &lsn_range, &mut new_jobs);
+                    }
+                }
             }
         }
 
@@ -599,8 +663,8 @@ where
     }
 }
 
-// Sliding window through keyspace and values
-// This is used by over_with_images to decide on good split points
+/// Sliding window through keyspace and values for image layer
+/// This is used by [`LevelCompactionState::cover_with_images`] to decide on good split points
 struct KeyspaceWindow<K> {
     head: KeyspaceWindowHead<K>,
 
@@ -740,9 +804,9 @@ struct WindowElement<K> {
     accum_size: u64,
 }
 
-// Sliding window through keyspace and values
-//
-// This is used to decide what layer to write next, from the beginning of the window.
+/// Sliding window through keyspace and values for delta layer tiling
+///
+/// This is used to decide which delta layer to write next.
 struct Window<K> {
     elems: VecDeque<WindowElement<K>>,
 
@@ -766,11 +830,13 @@ where
     fn feed(&mut self, key: K, size: u64) {
         let last_size;
         if let Some(last) = self.elems.back_mut() {
-            assert!(last.last_key <= key);
-            if key == last.last_key {
-                last.accum_size += size;
-                return;
-            }
+            // We require the keys to be strictly increasing for the window.
+            // Keys should already have been deduplicated by `accum_key_values`
+            assert!(
+                last.last_key < key,
+                "last_key(={}) >= key(={key})",
+                last.last_key
+            );
             last_size = last.accum_size;
         } else {
             last_size = 0;
@@ -792,6 +858,10 @@ where
         self.elems.front().unwrap().accum_size - self.splitoff_size
     }
 
+    fn is_empty(&self) -> bool {
+        self.elems.is_empty()
+    }
+
     fn commit_upto(&mut self, mut upto: usize) {
         while upto > 1 {
             let popped = self.elems.pop_front().unwrap();
@@ -854,7 +924,7 @@ where
         // If we're willing to stretch it up to 1.25 target size, could we
         // gobble up the rest of the work? This avoids creating very small
         // "tail" layers at the end of the keyspace
-        if !has_more && self.remain_size() < target_size * 5 / 3 {
+        if !has_more && self.remain_size() < target_size * 5 / 4 {
             self.commit_upto(self.elems.len());
         } else {
             let delta_split_at = self.find_size_split(target_size);

pageserver/compaction/src/helpers.rs

@@ -9,10 +9,14 @@ use pageserver_api::shard::ShardIdentity;
 use pin_project_lite::pin_project;
 use std::collections::BinaryHeap;
 use std::collections::VecDeque;
+use std::fmt::Display;
 use std::future::Future;
 use std::ops::{DerefMut, Range};
 use std::pin::Pin;
 use std::task::{ready, Poll};
+use utils::lsn::Lsn;
+
+pub const PAGE_SZ: u64 = 8192;
 
 pub fn keyspace_total_size<K>(
     keyspace: &CompactionKeySpace<K>,
@@ -108,17 +112,40 @@ pub fn merge_delta_keys<'a, E: CompactionJobExecutor>(
     }
 }
 
+pub async fn merge_delta_keys_buffered<'a, E: CompactionJobExecutor + 'a>(
+    layers: &'a [E::DeltaLayer],
+    ctx: &'a E::RequestContext,
+) -> anyhow::Result<impl Stream<Item = <E::DeltaLayer as CompactionDeltaLayer<E>>::DeltaEntry<'a>>>
+{
+    let mut keys = Vec::new();
+    for l in layers {
+        // Boxing and casting to LoadFuture is required to obtain the right Sync bound.
+        // If we do l.load_keys(ctx).await? directly, there is a compilation error.
+        let load_future: LoadFuture<'a, _> = Box::pin(l.load_keys(ctx));
+        keys.extend(load_future.await?.into_iter());
+    }
+    keys.sort_by_key(|k| (k.key(), k.lsn()));
+    let stream = futures::stream::iter(keys.into_iter());
+    Ok(stream)
+}
+
 enum LazyLoadLayer<'a, E: CompactionJobExecutor> {
     Loaded(VecDeque<<E::DeltaLayer as CompactionDeltaLayer<E>>::DeltaEntry<'a>>),
     Unloaded(&'a E::DeltaLayer),
 }
 impl<'a, E: CompactionJobExecutor> LazyLoadLayer<'a, E> {
-    fn key(&self) -> E::Key {
+    fn min_key(&self) -> E::Key {
         match self {
             Self::Loaded(entries) => entries.front().unwrap().key(),
             Self::Unloaded(dl) => dl.key_range().start,
         }
     }
+    fn min_lsn(&self) -> Lsn {
+        match self {
+            Self::Loaded(entries) => entries.front().unwrap().lsn(),
+            Self::Unloaded(dl) => dl.lsn_range().start,
+        }
+    }
 }
 impl<'a, E: CompactionJobExecutor> PartialOrd for LazyLoadLayer<'a, E> {
     fn partial_cmp(&self, other: &Self) -> Option<std::cmp::Ordering> {
@@ -128,12 +155,12 @@ impl<'a, E: CompactionJobExecutor> PartialOrd for LazyLoadLayer<'a, E> {
 impl<'a, E: CompactionJobExecutor> Ord for LazyLoadLayer<'a, E> {
     fn cmp(&self, other: &Self) -> std::cmp::Ordering {
         // reverse order so that we get a min-heap
-        other.key().cmp(&self.key())
+        (other.min_key(), other.min_lsn()).cmp(&(self.min_key(), self.min_lsn()))
     }
 }
 impl<'a, E: CompactionJobExecutor> PartialEq for LazyLoadLayer<'a, E> {
     fn eq(&self, other: &Self) -> bool {
-        self.key().eq(&other.key())
+        self.cmp(other) == std::cmp::Ordering::Equal
     }
 }
 impl<'a, E: CompactionJobExecutor> Eq for LazyLoadLayer<'a, E> {}
@@ -210,11 +237,16 @@ pub struct KeySize<K> {
     pub key: K,
     pub num_values: u64,
     pub size: u64,
+    /// The lsns to partition at (if empty then no per-lsn partitioning)
+    pub partition_lsns: Vec<(Lsn, u64)>,
 }
 
-pub fn accum_key_values<'a, I, K, D, E>(input: I) -> impl Stream<Item = Result<KeySize<K>, E>>
+pub fn accum_key_values<'a, I, K, D, E>(
+    input: I,
+    target_size: u64,
+) -> impl Stream<Item = Result<KeySize<K>, E>>
 where
-    K: Eq,
+    K: Eq + PartialOrd + Display + Copy,
     I: Stream<Item = Result<D, E>>,
     D: CompactionDeltaEntry<'a, K>,
 {
@@ -224,25 +256,39 @@ where
 
         if let Some(first) = input.next().await {
             let first = first?;
+            let mut part_size = first.size();
             let mut accum: KeySize<K> = KeySize {
                 key: first.key(),
                 num_values: 1,
-                size: first.size(),
+                size: part_size,
+                partition_lsns: Vec::new(),
             };
+            let mut last_key = accum.key;
             while let Some(this) = input.next().await {
                 let this = this?;
                 if this.key() == accum.key {
-                    accum.size += this.size();
+                    let add_size = this.size();
+                    if part_size + add_size > target_size {
+                        accum.partition_lsns.push((this.lsn(), part_size));
+                        part_size = 0;
+                    }
+                    part_size += add_size;
+                    accum.size += add_size;
                     accum.num_values += 1;
                 } else {
+                    assert!(last_key <= accum.key, "last_key={last_key} <= accum.key={}", accum.key);
+                    last_key = accum.key;
                     yield accum;
+                    part_size = this.size();
                     accum = KeySize {
                         key: this.key(),
                         num_values: 1,
-                        size: this.size(),
+                        size: part_size,
+                        partition_lsns: Vec::new(),
                     };
                 }
             }
+            assert!(last_key <= accum.key, "last_key={last_key} <= accum.key={}", accum.key);
             yield accum;
         }
     }

pageserver/compaction/src/identify_levels.rs

@@ -184,6 +184,12 @@ impl<L> Level<L> {
         }
         let mut events: Vec<Event<K>> = Vec::new();
         for (idx, l) in self.layers.iter().enumerate() {
+            let key_range = l.key_range();
+            if key_range.end == key_range.start.next() && l.is_delta() {
+                // Ignore single-key delta layers as they can be stacked on top of each other
+                // as that is the only way to cut further.
+                continue;
+            }
             events.push(Event {
                 key: l.key_range().start,
                 layer_idx: idx,

pageserver/compaction/src/simulator.rs

@@ -14,6 +14,7 @@ use std::ops::Range;
 use std::sync::Arc;
 use std::sync::Mutex;
 
+use crate::helpers::PAGE_SZ;
 use crate::helpers::{merge_delta_keys, overlaps_with};
 
 use crate::interface;
@@ -509,7 +510,7 @@ impl interface::CompactionJobExecutor for MockTimeline {
         let new_layer = Arc::new(MockImageLayer {
             key_range: key_range.clone(),
             lsn_range: lsn..lsn,
-            file_size: accum_size * 8192,
+            file_size: accum_size * PAGE_SZ,
             deleted: Mutex::new(false),
         });
         info!(

pageserver/compaction/tests/tests.rs

@@ -1,23 +1,35 @@
+use once_cell::sync::OnceCell;
 use pageserver_compaction::interface::CompactionLayer;
 use pageserver_compaction::simulator::MockTimeline;
+use utils::logging;
+
+static LOG_HANDLE: OnceCell<()> = OnceCell::new();
+
+pub(crate) fn setup_logging() {
+    LOG_HANDLE.get_or_init(|| {
+        logging::init(
+            logging::LogFormat::Test,
+            logging::TracingErrorLayerEnablement::EnableWithRustLogFilter,
+            logging::Output::Stdout,
+        )
+        .expect("Failed to init test logging")
+    });
+}
 
 /// Test the extreme case that there are so many updates for a single key that
 /// even if we produce an extremely narrow delta layer, spanning just that one
 /// key, we still too many records to fit in the target file size. We need to
 /// split in the LSN dimension too in that case.
-///
-/// TODO: The code to avoid this problem has not been implemented yet! So the
-/// assertion currently fails, but we need to make it not fail.
-#[ignore]
 #[tokio::test]
 async fn test_many_updates_for_single_key() {
+    setup_logging();
     let mut executor = MockTimeline::new();
-    executor.target_file_size = 10_000_000; // 10 MB
+    executor.target_file_size = 1_000_000; // 1 MB
 
-    // Ingest 100 MB of updates to a single key.
+    // Ingest 10 MB of updates to a single key.
     for _ in 1..1000 {
         executor.ingest_uniform(100, 10, &(0..100_000)).unwrap();
-        executor.ingest_uniform(10_000, 10, &(0..1)).unwrap();
+        executor.ingest_uniform(1000, 10, &(0..1)).unwrap();
         executor.compact().await.unwrap();
     }
 
@@ -27,9 +39,32 @@ async fn test_many_updates_for_single_key() {
     }
     for l in executor.live_layers.iter() {
         assert!(l.file_size() < executor.target_file_size * 2);
-        // sanity check that none of the delta layers are stupidly small either
+        // Sanity check that none of the delta layers are empty either.
         if l.is_delta() {
-            assert!(l.file_size() > executor.target_file_size / 2);
+            assert!(l.file_size() > 0);
         }
     }
 }
+
+#[tokio::test]
+async fn test_simple_updates() {
+    setup_logging();
+    let mut executor = MockTimeline::new();
+    executor.target_file_size = 500_000; // 500 KB
+
+    // Ingest some traffic.
+    for _ in 1..400 {
+        executor.ingest_uniform(100, 500, &(0..100_000)).unwrap();
+    }
+
+    for l in executor.live_layers.iter() {
+        println!("layer {}: {}", l.short_id(), l.file_size());
+    }
+
+    println!("Running compaction...");
+    executor.compact().await.unwrap();
+
+    for l in executor.live_layers.iter() {
+        println!("layer {}: {}", l.short_id(), l.file_size());
+    }
+}

pageserver/ctl/src/draw_timeline_dir.rs

@@ -28,6 +28,8 @@
 //! # From an `index_part.json` in S3
 //! (jq -r '.layer_metadata | keys[]' | cargo  run -p pagectl draw-timeline ) < index_part.json-00000016 > out.svg
 //!
+//! # enrich with lines for gc_cutoff and a child branch point
+//! cat <(jq -r '.historic_layers[] | .layer_file_name' < layers.json) <(echo -e 'gc_cutoff:0000001CE3FE32C9\nbranch:0000001DE3FE32C9') | cargo run --bin pagectl draw-timeline >| out.svg
 //! ```
 //!
 //! ## Viewing
@@ -48,9 +50,8 @@
 //! ```
 //!
 
-use anyhow::Result;
+use anyhow::{Context, Result};
 use pageserver::repository::Key;
-use pageserver::METADATA_FILE_NAME;
 use std::cmp::Ordering;
 use std::io::{self, BufRead};
 use std::path::PathBuf;
@@ -81,6 +82,11 @@ fn parse_filename(name: &str) -> (Range<Key>, Range<Lsn>) {
     let split: Vec<&str> = name.split("__").collect();
     let keys: Vec<&str> = split[0].split('-').collect();
     let mut lsns: Vec<&str> = split[1].split('-').collect();
+
+    if lsns.last().expect("should").len() == 8 {
+        lsns.pop();
+    }
+
     if lsns.len() == 1 {
         lsns.push(lsns[0]);
     }
@@ -90,6 +96,33 @@ fn parse_filename(name: &str) -> (Range<Key>, Range<Lsn>) {
     (keys, lsns)
 }
 
+#[derive(Clone, Copy)]
+enum LineKind {
+    GcCutoff,
+    Branch,
+}
+
+impl From<LineKind> for Fill {
+    fn from(value: LineKind) -> Self {
+        match value {
+            LineKind::GcCutoff => Fill::Color(rgb(255, 0, 0)),
+            LineKind::Branch => Fill::Color(rgb(0, 255, 0)),
+        }
+    }
+}
+
+impl FromStr for LineKind {
+    type Err = anyhow::Error;
+
+    fn from_str(s: &str) -> std::prelude::v1::Result<Self, Self::Err> {
+        Ok(match s {
+            "gc_cutoff" => LineKind::GcCutoff,
+            "branch" => LineKind::Branch,
+            _ => anyhow::bail!("unsupported linekind: {s}"),
+        })
+    }
+}
+
 pub fn main() -> Result<()> {
     // Parse layer filenames from stdin
     struct Layer {
@@ -99,15 +132,32 @@ pub fn main() -> Result<()> {
     }
     let mut files: Vec<Layer> = vec![];
     let stdin = io::stdin();
-    for line in stdin.lock().lines() {
+
+    let mut lines: Vec<(Lsn, LineKind)> = vec![];
+
+    for (lineno, line) in stdin.lock().lines().enumerate() {
+        let lineno = lineno + 1;
+
         let line = line.unwrap();
+        if let Some((kind, lsn)) = line.split_once(':') {
+            let (kind, lsn) = LineKind::from_str(kind)
+                .context("parse kind")
+                .and_then(|kind| {
+                    if lsn.contains('/') {
+                        Lsn::from_str(lsn)
+                    } else {
+                        Lsn::from_hex(lsn)
+                    }
+                    .map(|lsn| (kind, lsn))
+                    .context("parse lsn")
+                })
+                .with_context(|| format!("parse {line:?} on {lineno}"))?;
+            lines.push((lsn, kind));
+            continue;
+        }
         let line = PathBuf::from_str(&line).unwrap();
         let filename = line.file_name().unwrap();
         let filename = filename.to_str().unwrap();
-        if filename == METADATA_FILE_NAME {
-            // Don't try and parse "metadata" like a key-lsn range
-            continue;
-        }
         let (key_range, lsn_range) = parse_filename(filename);
         files.push(Layer {
             filename: filename.to_owned(),
@@ -117,8 +167,9 @@ pub fn main() -> Result<()> {
     }
 
     // Collect all coordinates
-    let mut keys: Vec<Key> = vec![];
-    let mut lsns: Vec<Lsn> = vec![];
+    let mut keys: Vec<Key> = Vec::with_capacity(files.len());
+    let mut lsns: Vec<Lsn> = Vec::with_capacity(files.len() + lines.len());
+
     for Layer {
         key_range: keyr,
         lsn_range: lsnr,
@@ -131,6 +182,8 @@ pub fn main() -> Result<()> {
         lsns.push(lsnr.end);
     }
 
+    lsns.extend(lines.iter().map(|(lsn, _)| *lsn));
+
     // Analyze
     let key_map = build_coordinate_compression_map(keys);
     let lsn_map = build_coordinate_compression_map(lsns);
@@ -144,10 +197,13 @@ pub fn main() -> Result<()> {
     println!(
         "{}",
         BeginSvg {
-            w: key_map.len() as f32,
+            w: (key_map.len() + 10) as f32,
             h: stretch * lsn_map.len() as f32
         }
     );
+
+    let xmargin = 0.05; // Height-dependent margin to disambiguate overlapping deltas
+
     for Layer {
         filename,
         key_range: keyr,
@@ -169,7 +225,6 @@ pub fn main() -> Result<()> {
         let mut lsn_diff = (lsn_end - lsn_start) as f32;
         let mut fill = Fill::None;
         let mut ymargin = 0.05 * lsn_diff; // Height-dependent margin to disambiguate overlapping deltas
-        let xmargin = 0.05; // Height-dependent margin to disambiguate overlapping deltas
         let mut lsn_offset = 0.0;
 
         // Fill in and thicken rectangle if it's an
@@ -189,7 +244,7 @@ pub fn main() -> Result<()> {
         println!(
             "    {}",
             rectangle(
-                key_start as f32 + stretch * xmargin,
+                5.0 + key_start as f32 + stretch * xmargin,
                 stretch * (lsn_max as f32 - (lsn_end as f32 - ymargin - lsn_offset)),
                 key_diff as f32 - stretch * 2.0 * xmargin,
                 stretch * (lsn_diff - 2.0 * ymargin)
@@ -200,6 +255,26 @@ pub fn main() -> Result<()> {
             .comment(filename)
         );
     }
+
+    for (lsn, kind) in lines {
+        let lsn_start = *lsn_map.get(&lsn).unwrap();
+        let lsn_end = lsn_start;
+        let stretch = 2.0;
+        let lsn_diff = 0.3;
+        let lsn_offset = -lsn_diff / 2.0;
+        let ymargin = 0.05;
+        println!(
+            "{}",
+            rectangle(
+                0.0f32 + stretch * xmargin,
+                stretch * (lsn_map.len() as f32 - (lsn_end as f32 - ymargin - lsn_offset)),
+                (key_map.len() + 10) as f32,
+                stretch * (lsn_diff - 2.0 * ymargin)
+            )
+            .fill(kind)
+        );
+    }
+
     println!("{}", EndSvg);
 
     eprintln!("num_images: {}", num_images);

pageserver/ctl/src/index_part.rs

@@ -3,7 +3,7 @@ use std::collections::HashMap;
 use anyhow::Context;
 use camino::Utf8PathBuf;
 use pageserver::tenant::remote_timeline_client::index::IndexLayerMetadata;
-use pageserver::tenant::storage_layer::LayerFileName;
+use pageserver::tenant::storage_layer::LayerName;
 use pageserver::tenant::{metadata::TimelineMetadata, IndexPart};
 use utils::lsn::Lsn;
 
@@ -19,7 +19,7 @@ pub(crate) async fn main(cmd: &IndexPartCmd) -> anyhow::Result<()> {
             let des: IndexPart = IndexPart::from_s3_bytes(&bytes).context("deserialize")?;
             #[derive(serde::Serialize)]
             struct Output<'a> {
-                layer_metadata: &'a HashMap<LayerFileName, IndexLayerMetadata>,
+                layer_metadata: &'a HashMap<LayerName, IndexLayerMetadata>,
                 disk_consistent_lsn: Lsn,
                 timeline_metadata: &'a TimelineMetadata,
             }

pageserver/ctl/src/layer_map_analyzer.rs

@@ -100,7 +100,7 @@ pub(crate) fn parse_filename(name: &str) -> Option<LayerFile> {
 
 // Finds the max_holes largest holes, ignoring any that are smaller than MIN_HOLE_LENGTH"
 async fn get_holes(path: &Utf8Path, max_holes: usize, ctx: &RequestContext) -> Result<Vec<Hole>> {
-    let file = VirtualFile::open(path).await?;
+    let file = VirtualFile::open(path, ctx).await?;
     let file_id = page_cache::next_file_id();
     let block_reader = FileBlockReader::new(&file, file_id);
     let summary_blk = block_reader.read_blk(0, ctx).await?;

pageserver/ctl/src/layers.rs

@@ -61,7 +61,7 @@ async fn read_delta_file(path: impl AsRef<Path>, ctx: &RequestContext) -> Result
     let path = Utf8Path::from_path(path.as_ref()).expect("non-Unicode path");
     virtual_file::init(10, virtual_file::api::IoEngineKind::StdFs);
     page_cache::init(100);
-    let file = VirtualFile::open(path).await?;
+    let file = VirtualFile::open(path, ctx).await?;
     let file_id = page_cache::next_file_id();
     let block_reader = FileBlockReader::new(&file, file_id);
     let summary_blk = block_reader.read_blk(0, ctx).await?;

pageserver/ctl/src/main.rs

@@ -219,6 +219,7 @@ fn handle_metadata(
     let mut meta = TimelineMetadata::from_bytes(&metadata_bytes)?;
     println!("Current metadata:\n{meta:?}");
     let mut update_meta = false;
+    // TODO: simplify this part
     if let Some(disk_consistent_lsn) = disk_consistent_lsn {
         meta = TimelineMetadata::new(
             *disk_consistent_lsn,

pageserver/pagebench/src/cmd/aux_files.rs

@@ -0,0 +1,98 @@
+use pageserver_api::models::{AuxFilePolicy, TenantConfig, TenantConfigRequest};
+use pageserver_api::shard::TenantShardId;
+use utils::id::TenantTimelineId;
+use utils::lsn::Lsn;
+
+use std::collections::HashMap;
+use std::sync::Arc;
+
+/// Ingest aux files into the pageserver.
+#[derive(clap::Parser)]
+pub(crate) struct Args {
+    #[clap(long, default_value = "http://localhost:9898")]
+    mgmt_api_endpoint: String,
+    #[clap(long, default_value = "postgres://postgres@localhost:64000")]
+    page_service_connstring: String,
+    #[clap(long)]
+    pageserver_jwt: Option<String>,
+
+    targets: Option<Vec<TenantTimelineId>>,
+}
+
+pub(crate) fn main(args: Args) -> anyhow::Result<()> {
+    let rt = tokio::runtime::Builder::new_multi_thread()
+        .enable_all()
+        .build()
+        .unwrap();
+
+    let main_task = rt.spawn(main_impl(args));
+    rt.block_on(main_task).unwrap()
+}
+
+async fn main_impl(args: Args) -> anyhow::Result<()> {
+    let args: &'static Args = Box::leak(Box::new(args));
+
+    let mgmt_api_client = Arc::new(pageserver_client::mgmt_api::Client::new(
+        args.mgmt_api_endpoint.clone(),
+        args.pageserver_jwt.as_deref(),
+    ));
+
+    // discover targets
+    let timelines: Vec<TenantTimelineId> = crate::util::cli::targets::discover(
+        &mgmt_api_client,
+        crate::util::cli::targets::Spec {
+            limit_to_first_n_targets: None,
+            targets: {
+                if let Some(targets) = &args.targets {
+                    if targets.len() != 1 {
+                        anyhow::bail!("must specify exactly one target");
+                    }
+                    Some(targets.clone())
+                } else {
+                    None
+                }
+            },
+        },
+    )
+    .await?;
+
+    let timeline = timelines[0];
+    let tenant_shard_id = TenantShardId::unsharded(timeline.tenant_id);
+    let timeline_id = timeline.timeline_id;
+
+    println!("operating on timeline {}", timeline);
+
+    mgmt_api_client
+        .tenant_config(&TenantConfigRequest {
+            tenant_id: timeline.tenant_id,
+            config: TenantConfig {
+                switch_aux_file_policy: Some(AuxFilePolicy::V2),
+                ..Default::default()
+            },
+        })
+        .await?;
+
+    for batch in 0..100 {
+        let items = (0..100)
+            .map(|id| {
+                (
+                    format!("pg_logical/mappings/{:03}.{:03}", batch, id),
+                    format!("{:08}", id),
+                )
+            })
+            .collect::<HashMap<_, _>>();
+        let file_cnt = items.len();
+        mgmt_api_client
+            .ingest_aux_files(tenant_shard_id, timeline_id, items)
+            .await?;
+        println!("ingested {file_cnt} files");
+    }
+
+    let files = mgmt_api_client
+        .list_aux_files(tenant_shard_id, timeline_id, Lsn(Lsn::MAX.0 - 1))
+        .await?;
+
+    println!("{} files found", files.len());
+
+    anyhow::Ok(())
+}

pageserver/pagebench/src/cmd/ondemand_download_churn.rs

@@ -2,9 +2,11 @@ use pageserver_api::{models::HistoricLayerInfo, shard::TenantShardId};
 
 use pageserver_client::mgmt_api;
 use rand::seq::SliceRandom;
+use tokio_util::sync::CancellationToken;
 use tracing::{debug, info};
 use utils::id::{TenantTimelineId, TimelineId};
 
+use std::{f64, sync::Arc};
 use tokio::{
     sync::{mpsc, OwnedSemaphorePermit},
     task::JoinSet,
@@ -12,10 +14,7 @@ use tokio::{
 
 use std::{
     num::NonZeroUsize,
-    sync::{
-        atomic::{AtomicU64, Ordering},
-        Arc,
-    },
+    sync::atomic::{AtomicU64, Ordering},
     time::{Duration, Instant},
 };
 
@@ -51,19 +50,31 @@ pub(crate) fn main(args: Args) -> anyhow::Result<()> {
     Ok(())
 }
 
+#[derive(serde::Serialize)]
+struct Output {
+    downloads_count: u64,
+    downloads_bytes: u64,
+    evictions_count: u64,
+    timeline_restarts: u64,
+    #[serde(with = "humantime_serde")]
+    runtime: Duration,
+}
+
 #[derive(Debug, Default)]
 struct LiveStats {
-    evictions: AtomicU64,
-    downloads: AtomicU64,
+    evictions_count: AtomicU64,
+    downloads_count: AtomicU64,
+    downloads_bytes: AtomicU64,
     timeline_restarts: AtomicU64,
 }
 
 impl LiveStats {
     fn eviction_done(&self) {
-        self.evictions.fetch_add(1, Ordering::Relaxed);
+        self.evictions_count.fetch_add(1, Ordering::Relaxed);
     }
-    fn download_done(&self) {
-        self.downloads.fetch_add(1, Ordering::Relaxed);
+    fn download_done(&self, size: u64) {
+        self.downloads_count.fetch_add(1, Ordering::Relaxed);
+        self.downloads_bytes.fetch_add(size, Ordering::Relaxed);
     }
     fn timeline_restart_done(&self) {
         self.timeline_restarts.fetch_add(1, Ordering::Relaxed);
@@ -92,28 +103,49 @@ async fn main_impl(args: Args) -> anyhow::Result<()> {
     )
     .await?;
 
+    let token = CancellationToken::new();
     let mut tasks = JoinSet::new();
 
-    let live_stats = Arc::new(LiveStats::default());
+    let periodic_stats = Arc::new(LiveStats::default());
+    let total_stats = Arc::new(LiveStats::default());
+
+    let start = Instant::now();
     tasks.spawn({
-        let live_stats = Arc::clone(&live_stats);
+        let periodic_stats = Arc::clone(&periodic_stats);
+        let total_stats = Arc::clone(&total_stats);
+        let cloned_token = token.clone();
         async move {
             let mut last_at = Instant::now();
             loop {
+                if cloned_token.is_cancelled() {
+                    return;
+                }
                 tokio::time::sleep_until((last_at + Duration::from_secs(1)).into()).await;
                 let now = Instant::now();
                 let delta: Duration = now - last_at;
                 last_at = now;
 
                 let LiveStats {
-                    evictions,
-                    downloads,
+                    evictions_count,
+                    downloads_count,
+                    downloads_bytes,
                     timeline_restarts,
-                } = &*live_stats;
-                let evictions = evictions.swap(0, Ordering::Relaxed) as f64 / delta.as_secs_f64();
-                let downloads = downloads.swap(0, Ordering::Relaxed) as f64 / delta.as_secs_f64();
+                } = &*periodic_stats;
+                let evictions_count = evictions_count.swap(0, Ordering::Relaxed);
+                let downloads_count = downloads_count.swap(0, Ordering::Relaxed);
+                let downloads_bytes = downloads_bytes.swap(0, Ordering::Relaxed);
                 let timeline_restarts = timeline_restarts.swap(0, Ordering::Relaxed);
-                info!("evictions={evictions:.2}/s downloads={downloads:.2}/s timeline_restarts={timeline_restarts}");
+
+                total_stats.evictions_count.fetch_add(evictions_count, Ordering::Relaxed);
+                total_stats.downloads_count.fetch_add(downloads_count, Ordering::Relaxed);
+                total_stats.downloads_bytes.fetch_add(downloads_bytes, Ordering::Relaxed);
+                total_stats.timeline_restarts.fetch_add(timeline_restarts, Ordering::Relaxed);
+
+                let evictions_per_s = evictions_count as f64 / delta.as_secs_f64();
+                let downloads_per_s = downloads_count as f64 / delta.as_secs_f64();
+                let downloads_mibs_per_s = downloads_bytes as f64 / delta.as_secs_f64() / ((1 << 20) as f64);
+
+                info!("evictions={evictions_per_s:.2}/s downloads={downloads_per_s:.2}/s download_bytes={downloads_mibs_per_s:.2}MiB/s timeline_restarts={timeline_restarts}");
             }
         }
     });
@@ -124,14 +156,42 @@ async fn main_impl(args: Args) -> anyhow::Result<()> {
                 args,
                 Arc::clone(&mgmt_api_client),
                 tl,
-                Arc::clone(&live_stats),
+                Arc::clone(&periodic_stats),
+                token.clone(),
             ));
         }
     }
+    if let Some(runtime) = args.runtime {
+        tokio::spawn(async move {
+            tokio::time::sleep(runtime.into()).await;
+            token.cancel();
+        });
+    }
 
     while let Some(res) = tasks.join_next().await {
         res.unwrap();
     }
+    let end = Instant::now();
+    let duration: Duration = end - start;
+
+    let output = {
+        let LiveStats {
+            evictions_count,
+            downloads_count,
+            downloads_bytes,
+            timeline_restarts,
+        } = &*total_stats;
+        Output {
+            downloads_count: downloads_count.load(Ordering::Relaxed),
+            downloads_bytes: downloads_bytes.load(Ordering::Relaxed),
+            evictions_count: evictions_count.load(Ordering::Relaxed),
+            timeline_restarts: timeline_restarts.load(Ordering::Relaxed),
+            runtime: duration,
+        }
+    };
+    let output = serde_json::to_string_pretty(&output).unwrap();
+    println!("{output}");
+
     Ok(())
 }
 
@@ -140,6 +200,7 @@ async fn timeline_actor(
     mgmt_api_client: Arc<pageserver_client::mgmt_api::Client>,
     timeline: TenantTimelineId,
     live_stats: Arc<LiveStats>,
+    token: CancellationToken,
 ) {
     // TODO: support sharding
     let tenant_shard_id = TenantShardId::unsharded(timeline.tenant_id);
@@ -149,7 +210,7 @@ async fn timeline_actor(
         layers: Vec<mpsc::Sender<OwnedSemaphorePermit>>,
         concurrency: Arc<tokio::sync::Semaphore>,
     }
-    loop {
+    while !token.is_cancelled() {
         debug!("restarting timeline");
         let layer_map_info = mgmt_api_client
             .layer_map_info(tenant_shard_id, timeline.timeline_id)
@@ -185,7 +246,7 @@ async fn timeline_actor(
 
         live_stats.timeline_restart_done();
 
-        loop {
+        while !token.is_cancelled() {
             assert!(!timeline.joinset.is_empty());
             if let Some(res) = timeline.joinset.try_join_next() {
                 debug!(?res, "a layer actor exited, should not happen");
@@ -255,7 +316,7 @@ async fn layer_actor(
                     .layer_ondemand_download(tenant_shard_id, timeline_id, layer.layer_file_name())
                     .await
                     .unwrap();
-                live_stats.download_done();
+                live_stats.download_done(layer.layer_file_size());
                 did_it
             }
         };

pageserver/pagebench/src/main.rs

@@ -14,6 +14,7 @@ mod util {
 
 /// The pagebench CLI sub-commands, dispatched in [`main`] below.
 mod cmd {
+    pub(super) mod aux_files;
     pub(super) mod basebackup;
     pub(super) mod getpage_latest_lsn;
     pub(super) mod ondemand_download_churn;
@@ -27,6 +28,7 @@ enum Args {
     GetPageLatestLsn(cmd::getpage_latest_lsn::Args),
     TriggerInitialSizeCalculation(cmd::trigger_initial_size_calculation::Args),
     OndemandDownloadChurn(cmd::ondemand_download_churn::Args),
+    AuxFiles(cmd::aux_files::Args),
 }
 
 fn main() {
@@ -46,6 +48,7 @@ fn main() {
             cmd::trigger_initial_size_calculation::main(args)
         }
         Args::OndemandDownloadChurn(args) => cmd::ondemand_download_churn::main(args),
+        Args::AuxFiles(args) => cmd::aux_files::main(args),
     }
     .unwrap()
 }

pageserver/src/aux_file.rs

@@ -1,14 +1,39 @@
+use std::sync::Arc;
+
+use ::metrics::IntGauge;
+use bytes::{Buf, BufMut, Bytes};
 use pageserver_api::key::{Key, AUX_KEY_PREFIX, METADATA_KEY_SIZE};
 use tracing::warn;
 
-/// Create a metadata key from a hash, encoded as [AUX_KEY_PREFIX, 2B directory prefix, first 13B of 128b xxhash].
+// BEGIN Copyright (c) 2017 Servo Contributors
+
+/// Const version of FNV hash.
+#[inline]
+#[must_use]
+pub const fn fnv_hash(bytes: &[u8]) -> u128 {
+    const INITIAL_STATE: u128 = 0x6c62272e07bb014262b821756295c58d;
+    const PRIME: u128 = 0x0000000001000000000000000000013B;
+
+    let mut hash = INITIAL_STATE;
+    let mut i = 0;
+    while i < bytes.len() {
+        hash ^= bytes[i] as u128;
+        hash = hash.wrapping_mul(PRIME);
+        i += 1;
+    }
+    hash
+}
+
+// END Copyright (c) 2017 Servo Contributors
+
+/// Create a metadata key from a hash, encoded as [AUX_KEY_PREFIX, 2B directory prefix, least significant 13B of FNV hash].
 fn aux_hash_to_metadata_key(dir_level1: u8, dir_level2: u8, data: &[u8]) -> Key {
-    let mut key = [0; METADATA_KEY_SIZE];
-    let hash = twox_hash::xxh3::hash128(data).to_be_bytes();
+    let mut key: [u8; 16] = [0; METADATA_KEY_SIZE];
+    let hash = fnv_hash(data).to_be_bytes();
     key[0] = AUX_KEY_PREFIX;
     key[1] = dir_level1;
     key[2] = dir_level2;
-    key[3..16].copy_from_slice(&hash[0..13]);
+    key[3..16].copy_from_slice(&hash[3..16]);
     Key::from_metadata_key_fixed_size(&key)
 }
 
@@ -61,6 +86,133 @@ pub fn encode_aux_file_key(path: &str) -> Key {
     }
 }
 
+const AUX_FILE_ENCODING_VERSION: u8 = 0x01;
+
+pub fn decode_file_value(val: &[u8]) -> anyhow::Result<Vec<(&str, &[u8])>> {
+    let mut ptr = val;
+    if ptr.is_empty() {
+        // empty value = no files
+        return Ok(Vec::new());
+    }
+    assert_eq!(
+        ptr.get_u8(),
+        AUX_FILE_ENCODING_VERSION,
+        "unsupported aux file value"
+    );
+    let mut files = vec![];
+    while ptr.has_remaining() {
+        let key_len = ptr.get_u32() as usize;
+        let key = &ptr[..key_len];
+        ptr.advance(key_len);
+        let val_len = ptr.get_u32() as usize;
+        let content = &ptr[..val_len];
+        ptr.advance(val_len);
+
+        let path = std::str::from_utf8(key)?;
+        files.push((path, content));
+    }
+    Ok(files)
+}
+
+/// Decode an aux file key-value pair into a list of files. The returned `Bytes` contains reference
+/// to the original value slice. Be cautious about memory consumption.
+pub fn decode_file_value_bytes(val: &Bytes) -> anyhow::Result<Vec<(String, Bytes)>> {
+    let mut ptr = val.clone();
+    if ptr.is_empty() {
+        // empty value = no files
+        return Ok(Vec::new());
+    }
+    assert_eq!(
+        ptr.get_u8(),
+        AUX_FILE_ENCODING_VERSION,
+        "unsupported aux file value"
+    );
+    let mut files = vec![];
+    while ptr.has_remaining() {
+        let key_len = ptr.get_u32() as usize;
+        let key = ptr.slice(..key_len);
+        ptr.advance(key_len);
+        let val_len = ptr.get_u32() as usize;
+        let content = ptr.slice(..val_len);
+        ptr.advance(val_len);
+
+        let path = std::str::from_utf8(&key)?.to_string();
+        files.push((path, content));
+    }
+    Ok(files)
+}
+
+pub fn encode_file_value(files: &[(&str, &[u8])]) -> anyhow::Result<Vec<u8>> {
+    if files.is_empty() {
+        // no files = empty value
+        return Ok(Vec::new());
+    }
+    let mut encoded = vec![];
+    encoded.put_u8(AUX_FILE_ENCODING_VERSION);
+    for (path, content) in files {
+        if path.len() > u32::MAX as usize {
+            anyhow::bail!("{} exceeds path size limit", path);
+        }
+        encoded.put_u32(path.len() as u32);
+        encoded.put_slice(path.as_bytes());
+        if content.len() > u32::MAX as usize {
+            anyhow::bail!("{} exceeds content size limit", path);
+        }
+        encoded.put_u32(content.len() as u32);
+        encoded.put_slice(content);
+    }
+    Ok(encoded)
+}
+
+/// An estimation of the size of aux files.
+pub struct AuxFileSizeEstimator {
+    aux_file_size_gauge: IntGauge,
+    size: Arc<std::sync::Mutex<Option<isize>>>,
+}
+
+impl AuxFileSizeEstimator {
+    pub fn new(aux_file_size_gauge: IntGauge) -> Self {
+        Self {
+            aux_file_size_gauge,
+            size: Arc::new(std::sync::Mutex::new(None)),
+        }
+    }
+
+    pub fn on_base_backup(&self, new_size: usize) {
+        let mut guard = self.size.lock().unwrap();
+        *guard = Some(new_size as isize);
+        self.report(new_size as isize);
+    }
+
+    pub fn on_add(&self, file_size: usize) {
+        let mut guard = self.size.lock().unwrap();
+        if let Some(size) = &mut *guard {
+            *size += file_size as isize;
+            self.report(*size);
+        }
+    }
+
+    pub fn on_remove(&self, file_size: usize) {
+        let mut guard = self.size.lock().unwrap();
+        if let Some(size) = &mut *guard {
+            *size -= file_size as isize;
+            self.report(*size);
+        }
+    }
+
+    pub fn on_update(&self, old_size: usize, new_size: usize) {
+        let mut guard = self.size.lock().unwrap();
+        if let Some(size) = &mut *guard {
+            *size += new_size as isize - old_size as isize;
+            self.report(*size);
+        }
+    }
+
+    pub fn report(&self, size: isize) {
+        self.aux_file_size_gauge.set(size as i64);
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;
@@ -69,15 +221,19 @@ mod tests {
     fn test_hash_portable() {
         // AUX file encoding requires the hash to be portable across all platforms. This test case checks
         // if the algorithm produces the same hash across different environments.
+
         assert_eq!(
-            305317690835051308206966631765527126151,
-            twox_hash::xxh3::hash128("test1".as_bytes())
+            265160408618497461376862998434862070044,
+            super::fnv_hash("test1".as_bytes())
         );
         assert_eq!(
-            85104974691013376326742244813280798847,
-            twox_hash::xxh3::hash128("test/test2".as_bytes())
+            295486155126299629456360817749600553988,
+            super::fnv_hash("test/test2".as_bytes())
+        );
+        assert_eq!(
+            144066263297769815596495629667062367629,
+            super::fnv_hash("".as_bytes())
         );
-        assert_eq!(0, twox_hash::xxh3::hash128("".as_bytes()));
     }
 
     #[test]
@@ -85,28 +241,45 @@ mod tests {
         // To correct retrieve AUX files, the generated keys for the same file must be the same for all versions
         // of the page server.
         assert_eq!(
-            "6200000101E5B20C5F8DD5AA3289D6D9EAFA",
-            encode_aux_file_key("pg_logical/mappings/test1").to_string()
+            "62000001017F8B83D94F7081693471ABF91C",
+            encode_aux_file_key("pg_logical/mappings/test1").to_string(),
         );
         assert_eq!(
-            "620000010239AAC544893139B26F501B97E6",
-            encode_aux_file_key("pg_logical/snapshots/test2").to_string()
+            "62000001027F8E83D94F7081693471ABFCCD",
+            encode_aux_file_key("pg_logical/snapshots/test2").to_string(),
         );
         assert_eq!(
-            "620000010300000000000000000000000000",
-            encode_aux_file_key("pg_logical/replorigin_checkpoint").to_string()
+            "62000001032E07BB014262B821756295C58D",
+            encode_aux_file_key("pg_logical/replorigin_checkpoint").to_string(),
         );
         assert_eq!(
-            "62000001FF8635AF2134B7266EC5B4189FD6",
-            encode_aux_file_key("pg_logical/unsupported").to_string()
+            "62000001FF4F38E1C74754E7D03C1A660178",
+            encode_aux_file_key("pg_logical/unsupported").to_string(),
         );
         assert_eq!(
-            "6200000201772D0E5D71DE14DA86142A1619",
+            "62000002017F8D83D94F7081693471ABFB92",
             encode_aux_file_key("pg_replslot/test3").to_string()
         );
         assert_eq!(
-            "620000FFFF1866EBEB53B807B26A2416F317",
-            encode_aux_file_key("other_file_not_supported").to_string()
+            "620000FFFF2B6ECC8AEF93F643DC44F15E03",
+            encode_aux_file_key("other_file_not_supported").to_string(),
+        );
+    }
+
+    #[test]
+    fn test_value_encoding() {
+        let files = vec![
+            ("pg_logical/1.file", "1111".as_bytes()),
+            ("pg_logical/2.file", "2222".as_bytes()),
+        ];
+        assert_eq!(
+            files,
+            decode_file_value(&encode_file_value(&files).unwrap()).unwrap()
+        );
+        let files = vec![];
+        assert_eq!(
+            files,
+            decode_file_value(&encode_file_value(&files).unwrap()).unwrap()
         );
     }
 }

pageserver/src/basebackup.rs

@@ -601,7 +601,7 @@ where
         // add zenith.signal file
         let mut zenith_signal = String::new();
         if self.prev_record_lsn == Lsn(0) {
-            if self.lsn == self.timeline.get_ancestor_lsn() {
+            if self.timeline.is_ancestor_lsn(self.lsn) {
                 write!(zenith_signal, "PREV LSN: none")
                     .map_err(|e| BasebackupError::Server(e.into()))?;
             } else {

pageserver/src/bin/pageserver.rs

@@ -3,6 +3,7 @@
 //! Main entry point for the Page Server executable.
 
 use std::env::{var, VarError};
+use std::io::Read;
 use std::sync::Arc;
 use std::time::Duration;
 use std::{env, ops::ControlFlow, str::FromStr};
@@ -151,37 +152,34 @@ fn initialize_config(
     workdir: &Utf8Path,
 ) -> anyhow::Result<ControlFlow<(), &'static PageServerConf>> {
     let init = arg_matches.get_flag("init");
-    let update_config = init || arg_matches.get_flag("update-config");
 
-    let (mut toml, config_file_exists) = if cfg_file_path.is_file() {
-        if init {
-            anyhow::bail!(
-                "Config file '{cfg_file_path}' already exists, cannot init it, use --update-config to update it",
-            );
+    let file_contents: Option<toml_edit::Document> = match std::fs::File::open(cfg_file_path) {
+        Ok(mut f) => {
+            if init {
+                anyhow::bail!("config file already exists: {cfg_file_path}");
+            }
+            let md = f.metadata().context("stat config file")?;
+            if md.is_file() {
+                let mut s = String::new();
+                f.read_to_string(&mut s).context("read config file")?;
+                Some(s.parse().context("parse config file toml")?)
+            } else {
+                anyhow::bail!("directory entry exists but is not a file: {cfg_file_path}");
+            }
+        }
+        Err(e) if e.kind() == std::io::ErrorKind::NotFound => None,
+        Err(e) => {
+            anyhow::bail!("open pageserver config: {e}: {cfg_file_path}");
         }
-        // Supplement the CLI arguments with the config file
-        let cfg_file_contents = std::fs::read_to_string(cfg_file_path)
-            .with_context(|| format!("Failed to read pageserver config at '{cfg_file_path}'"))?;
-        (
-            cfg_file_contents
-                .parse::<toml_edit::Document>()
-                .with_context(|| {
-                    format!("Failed to parse '{cfg_file_path}' as pageserver config")
-                })?,
-            true,
-        )
-    } else if cfg_file_path.exists() {
-        anyhow::bail!("Config file '{cfg_file_path}' exists but is not a regular file");
-    } else {
-        // We're initializing the tenant, so there's no config file yet
-        (
-            DEFAULT_CONFIG_FILE
-                .parse::<toml_edit::Document>()
-                .context("could not parse built-in config file")?,
-            false,
-        )
     };
 
+    let mut effective_config = file_contents.unwrap_or_else(|| {
+        DEFAULT_CONFIG_FILE
+            .parse()
+            .expect("unit tests ensure this works")
+    });
+
+    // Patch with overrides from the command line
     if let Some(values) = arg_matches.get_many::<String>("config-override") {
         for option_line in values {
             let doc = toml_edit::Document::from_str(option_line).with_context(|| {
@@ -189,22 +187,21 @@ fn initialize_config(
             })?;
 
             for (key, item) in doc.iter() {
-                if config_file_exists && update_config && key == "id" && toml.contains_key(key) {
-                    anyhow::bail!("Pageserver config file exists at '{cfg_file_path}' and has node id already, it cannot be overridden");
-                }
-                toml.insert(key, item.clone());
+                effective_config.insert(key, item.clone());
             }
         }
     }
 
-    debug!("Resulting toml: {toml}");
-    let conf = PageServerConf::parse_and_validate(&toml, workdir)
+    debug!("Resulting toml: {effective_config}");
+
+    // Construct the runtime representation
+    let conf = PageServerConf::parse_and_validate(&effective_config, workdir)
         .context("Failed to parse pageserver configuration")?;
 
-    if update_config {
+    if init {
         info!("Writing pageserver config to '{cfg_file_path}'");
 
-        std::fs::write(cfg_file_path, toml.to_string())
+        std::fs::write(cfg_file_path, effective_config.to_string())
             .with_context(|| format!("Failed to write pageserver config to '{cfg_file_path}'"))?;
         info!("Config successfully written to '{cfg_file_path}'")
     }
@@ -287,7 +284,6 @@ fn start_pageserver(
     ))
     .unwrap();
     pageserver::preinitialize_metrics();
-    pageserver::metrics::wal_redo::set_process_kind_metric(conf.walredo_process_kind);
 
     // If any failpoints were set from FAILPOINTS environment variable,
     // print them to the log for debugging purposes
@@ -519,16 +515,12 @@ fn start_pageserver(
         }
     });
 
-    let secondary_controller = if let Some(remote_storage) = &remote_storage {
-        secondary::spawn_tasks(
-            tenant_manager.clone(),
-            remote_storage.clone(),
-            background_jobs_barrier.clone(),
-            shutdown_pageserver.clone(),
-        )
-    } else {
-        secondary::null_controller()
-    };
+    let secondary_controller = secondary::spawn_tasks(
+        tenant_manager.clone(),
+        remote_storage.clone(),
+        background_jobs_barrier.clone(),
+        shutdown_pageserver.clone(),
+    );
 
     // shared state between the disk-usage backed eviction background task and the http endpoint
     // that allows triggering disk-usage based eviction manually. note that the http endpoint
@@ -536,15 +528,13 @@ fn start_pageserver(
     // been configured.
     let disk_usage_eviction_state: Arc<disk_usage_eviction_task::State> = Arc::default();
 
-    if let Some(remote_storage) = &remote_storage {
-        launch_disk_usage_global_eviction_task(
-            conf,
-            remote_storage.clone(),
-            disk_usage_eviction_state.clone(),
-            tenant_manager.clone(),
-            background_jobs_barrier.clone(),
-        )?;
-    }
+    launch_disk_usage_global_eviction_task(
+        conf,
+        remote_storage.clone(),
+        disk_usage_eviction_state.clone(),
+        tenant_manager.clone(),
+        background_jobs_barrier.clone(),
+    )?;
 
     // Start up the service to handle HTTP mgmt API request. We created the
     // listener earlier already.
@@ -657,17 +647,20 @@ fn start_pageserver(
             None,
             "libpq endpoint listener",
             true,
-            async move {
-                page_service::libpq_listener_main(
-                    conf,
-                    broker_client,
-                    pg_auth,
-                    pageserver_listener,
-                    conf.pg_auth_type,
-                    libpq_ctx,
-                    task_mgr::shutdown_token(),
-                )
-                .await
+            {
+                let tenant_manager = tenant_manager.clone();
+                async move {
+                    page_service::libpq_listener_main(
+                        tenant_manager,
+                        broker_client,
+                        pg_auth,
+                        pageserver_listener,
+                        conf.pg_auth_type,
+                        libpq_ctx,
+                        task_mgr::shutdown_token(),
+                    )
+                    .await
+                }
             },
         );
     }
@@ -696,14 +689,7 @@ fn start_pageserver(
             // Right now that tree doesn't reach very far, and `task_mgr` is used instead.
             // The plan is to change that over time.
             shutdown_pageserver.take();
-            let bg_remote_storage = remote_storage.clone();
-            let bg_deletion_queue = deletion_queue.clone();
-            pageserver::shutdown_pageserver(
-                &tenant_manager,
-                bg_remote_storage.map(|_| bg_deletion_queue),
-                0,
-            )
-            .await;
+            pageserver::shutdown_pageserver(&tenant_manager, deletion_queue.clone(), 0).await;
             unreachable!()
         })
     }
@@ -711,12 +697,11 @@ fn start_pageserver(
 
 fn create_remote_storage_client(
     conf: &'static PageServerConf,
-) -> anyhow::Result<Option<GenericRemoteStorage>> {
+) -> anyhow::Result<GenericRemoteStorage> {
     let config = if let Some(config) = &conf.remote_storage_config {
         config
     } else {
-        tracing::warn!("no remote storage configured, this is a deprecated configuration");
-        return Ok(None);
+        anyhow::bail!("no remote storage configured, this is a deprecated configuration");
     };
 
     // Create the client
@@ -736,7 +721,7 @@ fn create_remote_storage_client(
             GenericRemoteStorage::unreliable_wrapper(remote_storage, conf.test_remote_failures);
     }
 
-    Ok(Some(remote_storage))
+    Ok(remote_storage)
 }
 
 fn cli() -> Command {
@@ -758,18 +743,13 @@ fn cli() -> Command {
         // See `settings.md` for more details on the extra configuration patameters pageserver can process
         .arg(
             Arg::new("config-override")
+                .long("config-override")
                 .short('c')
                 .num_args(1)
                 .action(ArgAction::Append)
                 .help("Additional configuration overrides of the ones from the toml config file (or new ones to add there). \
                 Any option has to be a valid toml document, example: `-c=\"foo='hey'\"` `-c=\"foo={value=1}\"`"),
         )
-        .arg(
-            Arg::new("update-config")
-                .long("update-config")
-                .action(ArgAction::SetTrue)
-                .help("Update the config file when started"),
-        )
         .arg(
             Arg::new("enabled-features")
                 .long("enabled-features")

pageserver/src/config.rs

@@ -9,7 +9,7 @@ use pageserver_api::shard::TenantShardId;
 use remote_storage::{RemotePath, RemoteStorageConfig};
 use serde;
 use serde::de::IntoDeserializer;
-use std::{collections::HashMap, env};
+use std::env;
 use storage_broker::Uri;
 use utils::crashsafe::path_with_suffix_extension;
 use utils::id::ConnectionId;
@@ -51,7 +51,7 @@ pub mod defaults {
     use crate::tenant::config::defaults::*;
     use const_format::formatcp;
 
-    pub use pageserver_api::{
+    pub use pageserver_api::config::{
         DEFAULT_HTTP_LISTEN_ADDR, DEFAULT_HTTP_LISTEN_PORT, DEFAULT_PG_LISTEN_ADDR,
         DEFAULT_PG_LISTEN_PORT,
     };
@@ -99,7 +99,7 @@ pub mod defaults {
 
     pub const DEFAULT_EPHEMERAL_BYTES_PER_MEMORY_KB: usize = 0;
 
-    pub const DEFAULT_WALREDO_PROCESS_KIND: &str = "sync";
+    pub const DEFAULT_WALREDO_PROCESS_KIND: &str = "async";
 
     ///
     /// Default built-in configuration file.
@@ -335,26 +335,6 @@ impl<T: Clone> BuilderValue<T> {
     }
 }
 
-// Certain metadata (e.g. externally-addressable name, AZ) is delivered
-// as a separate structure.  This information is not neeed by the pageserver
-// itself, it is only used for registering the pageserver with the control
-// plane and/or storage controller.
-//
-#[derive(serde::Deserialize)]
-pub(crate) struct NodeMetadata {
-    #[serde(rename = "host")]
-    pub(crate) postgres_host: String,
-    #[serde(rename = "port")]
-    pub(crate) postgres_port: u16,
-    pub(crate) http_host: String,
-    pub(crate) http_port: u16,
-
-    // Deployment tools may write fields to the metadata file beyond what we
-    // use in this type: this type intentionally only names fields that require.
-    #[serde(flatten)]
-    pub(crate) other: HashMap<String, serde_json::Value>,
-}
-
 // needed to simplify config construction
 #[derive(Default)]
 struct PageServerConfigBuilder {

pageserver/src/control_plane_client.rs

@@ -14,10 +14,8 @@ use tokio_util::sync::CancellationToken;
 use url::Url;
 use utils::{backoff, failpoint_support, generation::Generation, id::NodeId};
 
-use crate::{
-    config::{NodeMetadata, PageServerConf},
-    virtual_file::on_fatal_io_error,
-};
+use crate::{config::PageServerConf, virtual_file::on_fatal_io_error};
+use pageserver_api::config::NodeMetadata;
 
 /// The Pageserver's client for using the control plane API: this is a small subset
 /// of the overall control plane API, for dealing with generations (see docs/rfcs/025-generation-numbers.md)
@@ -65,7 +63,7 @@ impl ControlPlaneClient {
         let mut client = reqwest::ClientBuilder::new();
 
         if let Some(jwt) = &conf.control_plane_api_token {
-            let mut headers = hyper::HeaderMap::new();
+            let mut headers = reqwest::header::HeaderMap::new();
             headers.insert(
                 "Authorization",
                 format!("Bearer {}", jwt.get_contents()).parse().unwrap(),

pageserver/src/deletion_queue.rs

@@ -38,7 +38,7 @@ use deleter::DeleterMessage;
 use list_writer::ListWriterQueueMessage;
 use validator::ValidatorQueueMessage;
 
-use crate::{config::PageServerConf, tenant::storage_layer::LayerFileName};
+use crate::{config::PageServerConf, tenant::storage_layer::LayerName};
 
 // TODO: configurable for how long to wait before executing deletions
 
@@ -479,7 +479,7 @@ impl DeletionQueueClient {
         tenant_shard_id: TenantShardId,
         timeline_id: TimelineId,
         current_generation: Generation,
-        layers: Vec<(LayerFileName, LayerFileMetadata)>,
+        layers: Vec<(LayerName, LayerFileMetadata)>,
     ) -> Result<(), DeletionQueueError> {
         if current_generation.is_none() {
             debug!("Enqueuing deletions in legacy mode, skipping queue");
@@ -511,7 +511,7 @@ impl DeletionQueueClient {
         tenant_shard_id: TenantShardId,
         timeline_id: TimelineId,
         current_generation: Generation,
-        layers: Vec<(LayerFileName, LayerFileMetadata)>,
+        layers: Vec<(LayerName, LayerFileMetadata)>,
     ) -> Result<(), DeletionQueueError> {
         metrics::DELETION_QUEUE
             .keys_submitted
@@ -632,7 +632,7 @@ impl DeletionQueue {
     ///
     /// If remote_storage is None, then the returned workers will also be None.
     pub fn new<C>(
-        remote_storage: Option<GenericRemoteStorage>,
+        remote_storage: GenericRemoteStorage,
         control_plane_client: Option<C>,
         conf: &'static PageServerConf,
     ) -> (Self, Option<DeletionQueueWorkers<C>>)
@@ -658,23 +658,6 @@ impl DeletionQueue {
         // longer to flush after Tenants have all been torn down.
         let cancel = CancellationToken::new();
 
-        let remote_storage = match remote_storage {
-            None => {
-                return (
-                    Self {
-                        client: DeletionQueueClient {
-                            tx,
-                            executor_tx,
-                            lsn_table: lsn_table.clone(),
-                        },
-                        cancel,
-                    },
-                    None,
-                )
-            }
-            Some(r) => r,
-        };
-
         (
             Self {
                 client: DeletionQueueClient {
@@ -734,20 +717,20 @@ mod test {
     use crate::{
         control_plane_client::RetryForeverError,
         repository::Key,
-        tenant::{harness::TenantHarness, storage_layer::DeltaFileName},
+        tenant::{harness::TenantHarness, storage_layer::DeltaLayerName},
     };
 
     use super::*;
     pub const TIMELINE_ID: TimelineId =
         TimelineId::from_array(hex!("11223344556677881122334455667788"));
 
-    pub const EXAMPLE_LAYER_NAME: LayerFileName = LayerFileName::Delta(DeltaFileName {
+    pub const EXAMPLE_LAYER_NAME: LayerName = LayerName::Delta(DeltaLayerName {
         key_range: Key::from_i128(0x0)..Key::from_i128(0xFFFFFFFFFFFFFFFF),
         lsn_range: Lsn(0x00000000016B59D8)..Lsn(0x00000000016B5A51),
     });
 
     // When you need a second layer in a test.
-    pub const EXAMPLE_LAYER_NAME_ALT: LayerFileName = LayerFileName::Delta(DeltaFileName {
+    pub const EXAMPLE_LAYER_NAME_ALT: LayerName = LayerName::Delta(DeltaLayerName {
         key_range: Key::from_i128(0x0)..Key::from_i128(0xFFFFFFFFFFFFFFFF),
         lsn_range: Lsn(0x00000000016B5A51)..Lsn(0x00000000016B5A61),
     });
@@ -765,7 +748,7 @@ mod test {
         /// Simulate a pageserver restart by destroying and recreating the deletion queue
         async fn restart(&mut self) {
             let (deletion_queue, workers) = DeletionQueue::new(
-                Some(self.storage.clone()),
+                self.storage.clone(),
                 Some(self.mock_control_plane.clone()),
                 self.harness.conf,
             );
@@ -797,7 +780,7 @@ mod test {
         /// Returns remote layer file name, suitable for use in assert_remote_files
         fn write_remote_layer(
             &self,
-            file_name: LayerFileName,
+            file_name: LayerName,
             gen: Generation,
         ) -> anyhow::Result<String> {
             let tenant_shard_id = self.harness.tenant_shard_id;
@@ -875,7 +858,7 @@ mod test {
         let mock_control_plane = MockControlPlane::new();
 
         let (deletion_queue, worker) = DeletionQueue::new(
-            Some(storage.clone()),
+            storage.clone(),
             Some(mock_control_plane.clone()),
             harness.conf,
         );
@@ -952,7 +935,7 @@ mod test {
         let client = ctx.deletion_queue.new_client();
         client.recover(HashMap::new())?;
 
-        let layer_file_name_1: LayerFileName = "000000000000000000000000000000000000-FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF__00000000016B59D8-00000000016B5A51".parse().unwrap();
+        let layer_file_name_1: LayerName = "000000000000000000000000000000000000-FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF__00000000016B59D8-00000000016B5A51".parse().unwrap();
         let tenant_shard_id = ctx.harness.tenant_shard_id;
 
         let content: Vec<u8> = "victim1 contents".into();

pageserver/src/deletion_queue/list_writer.rs

@@ -34,7 +34,7 @@ use crate::deletion_queue::TEMP_SUFFIX;
 use crate::metrics;
 use crate::tenant::remote_timeline_client::remote_layer_path;
 use crate::tenant::remote_timeline_client::LayerFileMetadata;
-use crate::tenant::storage_layer::LayerFileName;
+use crate::tenant::storage_layer::LayerName;
 use crate::virtual_file::on_fatal_io_error;
 use crate::virtual_file::MaybeFatalIo;
 
@@ -59,7 +59,7 @@ pub(super) struct DeletionOp {
     // `layers` and `objects` are both just lists of objects.  `layers` is used if you do not
     // have a config object handy to project it to a remote key, and need the consuming worker
     // to do it for you.
-    pub(super) layers: Vec<(LayerFileName, LayerFileMetadata)>,
+    pub(super) layers: Vec<(LayerName, LayerFileMetadata)>,
     pub(super) objects: Vec<RemotePath>,
 
     /// The _current_ generation of the Tenant shard attachment in which we are enqueuing

pageserver/src/disk_usage_eviction_task.rs

@@ -64,7 +64,7 @@ use crate::{
         mgr::TenantManager,
         remote_timeline_client::LayerFileMetadata,
         secondary::SecondaryTenant,
-        storage_layer::{AsLayerDesc, EvictionError, Layer, LayerFileName},
+        storage_layer::{AsLayerDesc, EvictionError, Layer, LayerName},
     },
 };
 
@@ -535,12 +535,11 @@ pub(crate) async fn disk_usage_eviction_task_iteration_impl<U: Usage>(
                 }
                 EvictionLayer::Secondary(layer) => {
                     let file_size = layer.metadata.file_size();
-                    let tenant_manager = tenant_manager.clone();
 
                     js.spawn(async move {
                         layer
                             .secondary_tenant
-                            .evict_layer(tenant_manager.get_conf(), layer.timeline_id, layer.name)
+                            .evict_layer(layer.timeline_id, layer.name)
                             .await;
                         Ok(file_size)
                     });
@@ -599,7 +598,7 @@ pub(crate) async fn disk_usage_eviction_task_iteration_impl<U: Usage>(
 pub(crate) struct EvictionSecondaryLayer {
     pub(crate) secondary_tenant: Arc<SecondaryTenant>,
     pub(crate) timeline_id: TimelineId,
-    pub(crate) name: LayerFileName,
+    pub(crate) name: LayerName,
     pub(crate) metadata: LayerFileMetadata,
 }
 
@@ -632,9 +631,9 @@ impl EvictionLayer {
         }
     }
 
-    pub(crate) fn get_name(&self) -> LayerFileName {
+    pub(crate) fn get_name(&self) -> LayerName {
         match self {
-            Self::Attached(l) => l.layer_desc().filename(),
+            Self::Attached(l) => l.layer_desc().layer_name(),
             Self::Secondary(sl) => sl.name.clone(),
         }
     }

pageserver/src/http/openapi_spec.yml

@@ -420,25 +420,6 @@ paths:
           description: Tenant scheduled to load successfully
 
   /v1/tenant/{tenant_id}/synthetic_size:
-    parameters:
-      - name: tenant_id
-        in: path
-        required: true
-        schema:
-          type: string
-    get:
-      description: |
-        Calculate tenant's synthetic size
-      responses:
-        "200":
-          description: Tenant's synthetic size
-          content:
-            application/json:
-              schema:
-                $ref: "#/components/schemas/SyntheticSizeResponse"
-
-  # This route has no handler. TODO: remove?
-  /v1/tenant/{tenant_id}/size:
     parameters:
       - name: tenant_id
         in: path
@@ -468,19 +449,9 @@ paths:
           content:
             application/json:
               schema:
-                type: object
-                required:
-                  - id
-                  - size
-                properties:
-                  id:
-                    type: string
-                    format: hex
-                  size:
-                    type: integer
-                    nullable: true
-                    description: |
-                      Size metric in bytes or null if inputs_only=true was given.
+                $ref: "#/components/schemas/SyntheticSizeResponse"
+            text/html:
+              description: SVG representation of the tenant and it's timelines.
         "401":
           description: Unauthorized Error
           content:
@@ -782,9 +753,6 @@ components:
       required:
         - mode
       properties:
-        tenant_id:
-          type: string
-          description: Not used, scheduled for removal.
         mode:
           type: string
           enum: ["AttachedSingle", "AttachedMulti", "AttachedStale", "Secondary", "Detached"]
@@ -932,6 +900,9 @@ components:
           format: hex
         size:
           type: integer
+          nullable: true
+          description: |
+            Size metric in bytes or null if inputs_only=true was given.
         segment_sizes:
           type: array
           items:

pageserver/src/http/routes.rs

@@ -1,6 +1,8 @@
 //!
 //! Management HTTP API
 //!
+use std::cmp::Reverse;
+use std::collections::BinaryHeap;
 use std::collections::HashMap;
 use std::str::FromStr;
 use std::sync::Arc;
@@ -14,6 +16,8 @@ use hyper::header;
 use hyper::StatusCode;
 use hyper::{Body, Request, Response, Uri};
 use metrics::launch_timestamp::LaunchTimestamp;
+use pageserver_api::models::IngestAuxFilesRequest;
+use pageserver_api::models::ListAuxFilesRequest;
 use pageserver_api::models::LocationConfig;
 use pageserver_api::models::LocationConfigListResponse;
 use pageserver_api::models::ShardParameters;
@@ -24,7 +28,11 @@ use pageserver_api::models::TenantScanRemoteStorageShard;
 use pageserver_api::models::TenantShardLocation;
 use pageserver_api::models::TenantShardSplitRequest;
 use pageserver_api::models::TenantShardSplitResponse;
+use pageserver_api::models::TenantSorting;
 use pageserver_api::models::TenantState;
+use pageserver_api::models::TopTenantShardItem;
+use pageserver_api::models::TopTenantShardsRequest;
+use pageserver_api::models::TopTenantShardsResponse;
 use pageserver_api::models::{
     DownloadRemoteLayersTaskSpawnRequest, LocationConfigMode, TenantAttachRequest,
     TenantLoadRequest, TenantLocationConfigRequest,
@@ -63,6 +71,7 @@ use crate::tenant::remote_timeline_client::list_remote_timelines;
 use crate::tenant::secondary::SecondaryController;
 use crate::tenant::size::ModelInputs;
 use crate::tenant::storage_layer::LayerAccessStatsReset;
+use crate::tenant::storage_layer::LayerName;
 use crate::tenant::timeline::CompactFlags;
 use crate::tenant::timeline::Timeline;
 use crate::tenant::SpawnMode;
@@ -103,7 +112,7 @@ pub struct State {
     tenant_manager: Arc<TenantManager>,
     auth: Option<Arc<SwappableJwtAuth>>,
     allowlist_routes: Vec<Uri>,
-    remote_storage: Option<GenericRemoteStorage>,
+    remote_storage: GenericRemoteStorage,
     broker_client: storage_broker::BrokerClientChannel,
     disk_usage_eviction_state: Arc<disk_usage_eviction_task::State>,
     deletion_queue_client: DeletionQueueClient,
@@ -117,7 +126,7 @@ impl State {
         conf: &'static PageServerConf,
         tenant_manager: Arc<TenantManager>,
         auth: Option<Arc<SwappableJwtAuth>>,
-        remote_storage: Option<GenericRemoteStorage>,
+        remote_storage: GenericRemoteStorage,
         broker_client: storage_broker::BrokerClientChannel,
         disk_usage_eviction_state: Arc<disk_usage_eviction_task::State>,
         deletion_queue_client: DeletionQueueClient,
@@ -432,6 +441,8 @@ async fn build_timeline_info_common(
         state,
 
         walreceiver_status,
+
+        last_aux_file_policy: timeline.last_aux_file_policy.load(),
     };
     Ok(info)
 }
@@ -812,12 +823,6 @@ async fn tenant_attach_handler(
 
     let generation = get_request_generation(state, maybe_body.as_ref().and_then(|r| r.generation))?;
 
-    if state.remote_storage.is_none() {
-        return Err(ApiError::BadRequest(anyhow!(
-            "attach_tenant is not possible because pageserver was configured without remote storage"
-        )));
-    }
-
     let tenant_shard_id = TenantShardId::unsharded(tenant_id);
     let shard_params = ShardParameters::default();
     let location_conf = LocationConf::attached_single(tenant_conf, generation, &shard_params);
@@ -1228,13 +1233,15 @@ async fn layer_download_handler(
     let timeline_id: TimelineId = parse_request_param(&request, "timeline_id")?;
     let layer_file_name = get_request_param(&request, "layer_file_name")?;
     check_permission(&request, Some(tenant_shard_id.tenant_id))?;
+    let layer_name = LayerName::from_str(layer_file_name)
+        .map_err(|s| ApiError::BadRequest(anyhow::anyhow!(s)))?;
     let state = get_state(&request);
 
     let timeline =
         active_timeline_of_active_tenant(&state.tenant_manager, tenant_shard_id, timeline_id)
             .await?;
     let downloaded = timeline
-        .download_layer(layer_file_name)
+        .download_layer(&layer_name)
         .await
         .map_err(ApiError::InternalServerError)?;
 
@@ -1258,11 +1265,14 @@ async fn evict_timeline_layer_handler(
     let layer_file_name = get_request_param(&request, "layer_file_name")?;
     let state = get_state(&request);
 
+    let layer_name = LayerName::from_str(layer_file_name)
+        .map_err(|s| ApiError::BadRequest(anyhow::anyhow!(s)))?;
+
     let timeline =
         active_timeline_of_active_tenant(&state.tenant_manager, tenant_shard_id, timeline_id)
             .await?;
     let evicted = timeline
-        .evict_layer(layer_file_name)
+        .evict_layer(&layer_name)
         .await
         .map_err(ApiError::InternalServerError)?;
 
@@ -1637,12 +1647,6 @@ async fn tenant_time_travel_remote_storage_handler(
         )));
     }
 
-    let Some(storage) = state.remote_storage.as_ref() else {
-        return Err(ApiError::InternalServerError(anyhow::anyhow!(
-            "remote storage not configured, cannot run time travel"
-        )));
-    };
-
     if timestamp > done_if_after {
         return Err(ApiError::BadRequest(anyhow!(
             "The done_if_after timestamp comes before the timestamp to recover to"
@@ -1652,7 +1656,7 @@ async fn tenant_time_travel_remote_storage_handler(
     tracing::info!("Issuing time travel request internally. timestamp={timestamp_raw}, done_if_after={done_if_after_raw}");
 
     remote_timeline_client::upload::time_travel_recover_tenant(
-        storage,
+        &state.remote_storage,
         &tenant_shard_id,
         timestamp,
         done_if_after,
@@ -1709,12 +1713,7 @@ async fn timeline_gc_handler(
     let gc_req: TimelineGcRequest = json_request(&mut request).await?;
 
     let ctx = RequestContext::new(TaskKind::MgmtRequest, DownloadBehavior::Download);
-    let wait_task_done = mgr::immediate_gc(tenant_shard_id, timeline_id, gc_req, cancel, &ctx)?;
-    let gc_result = wait_task_done
-        .await
-        .context("wait for gc task")
-        .map_err(ApiError::InternalServerError)?
-        .map_err(ApiError::InternalServerError)?;
+    let gc_result = mgr::immediate_gc(tenant_shard_id, timeline_id, gc_req, cancel, &ctx).await?;
 
     json_response(StatusCode::OK, gc_result)
 }
@@ -1827,17 +1826,81 @@ async fn timeline_download_remote_layers_handler_get(
     json_response(StatusCode::OK, info)
 }
 
+async fn timeline_detach_ancestor_handler(
+    request: Request<Body>,
+    _cancel: CancellationToken,
+) -> Result<Response<Body>, ApiError> {
+    use crate::tenant::timeline::detach_ancestor::Options;
+    let tenant_shard_id: TenantShardId = parse_request_param(&request, "tenant_shard_id")?;
+    check_permission(&request, Some(tenant_shard_id.tenant_id))?;
+    let timeline_id: TimelineId = parse_request_param(&request, "timeline_id")?;
+
+    let span = tracing::info_span!("detach_ancestor", tenant_id=%tenant_shard_id.tenant_id, shard_id=%tenant_shard_id.shard_slug(), %timeline_id);
+
+    async move {
+        let mut options = Options::default();
+
+        let rewrite_concurrency =
+            parse_query_param::<_, std::num::NonZeroUsize>(&request, "rewrite_concurrency")?;
+        let copy_concurrency =
+            parse_query_param::<_, std::num::NonZeroUsize>(&request, "copy_concurrency")?;
+
+        [
+            (&mut options.rewrite_concurrency, rewrite_concurrency),
+            (&mut options.copy_concurrency, copy_concurrency),
+        ]
+        .into_iter()
+        .filter_map(|(target, val)| val.map(|val| (target, val)))
+        .for_each(|(target, val)| *target = val);
+
+        let state = get_state(&request);
+
+        let tenant = state
+            .tenant_manager
+            .get_attached_tenant_shard(tenant_shard_id)?;
+
+        tenant.wait_to_become_active(ACTIVE_TENANT_TIMEOUT).await?;
+
+        let ctx = RequestContext::new(TaskKind::DetachAncestor, DownloadBehavior::Download);
+        let ctx = &ctx;
+
+        let timeline = tenant
+            .get_timeline(timeline_id, true)
+            .map_err(|e| ApiError::NotFound(e.into()))?;
+
+        let (_guard, prepared) = timeline
+            .prepare_to_detach_from_ancestor(&tenant, options, ctx)
+            .await
+            .map_err(|e| ApiError::InternalServerError(e.into()))?;
+
+        let res = state
+            .tenant_manager
+            .complete_detaching_timeline_ancestor(tenant_shard_id, timeline_id, prepared, ctx)
+            .await;
+
+        match res {
+            Ok(reparented_timelines) => {
+                let resp = pageserver_api::models::detach_ancestor::AncestorDetached {
+                    reparented_timelines,
+                };
+
+                json_response(StatusCode::OK, resp)
+            }
+            Err(e) => Err(ApiError::InternalServerError(
+                e.context("timeline detach completion"),
+            )),
+        }
+    }
+    .instrument(span)
+    .await
+}
+
 async fn deletion_queue_flush(
     r: Request<Body>,
     cancel: CancellationToken,
 ) -> Result<Response<Body>, ApiError> {
     let state = get_state(&r);
 
-    if state.remote_storage.is_none() {
-        // Nothing to do if remote storage is disabled.
-        return json_response(StatusCode::OK, ());
-    }
-
     let execute = parse_query_param(&r, "execute")?.unwrap_or(false);
 
     let flush = async {
@@ -2002,18 +2065,11 @@ async fn disk_usage_eviction_run(
     };
 
     let state = get_state(&r);
-
-    let Some(storage) = state.remote_storage.as_ref() else {
-        return Err(ApiError::InternalServerError(anyhow::anyhow!(
-            "remote storage not configured, cannot run eviction iteration"
-        )));
-    };
-
     let eviction_state = state.disk_usage_eviction_state.clone();
 
     let res = crate::disk_usage_eviction_task::disk_usage_eviction_task_iteration_impl(
         &eviction_state,
-        storage,
+        &state.remote_storage,
         usage,
         &state.tenant_manager,
         config.eviction_order,
@@ -2050,29 +2106,23 @@ async fn tenant_scan_remote_handler(
     let state = get_state(&request);
     let tenant_id: TenantId = parse_request_param(&request, "tenant_id")?;
 
-    let Some(remote_storage) = state.remote_storage.as_ref() else {
-        return Err(ApiError::BadRequest(anyhow::anyhow!(
-            "Remote storage not configured"
-        )));
-    };
-
     let mut response = TenantScanRemoteStorageResponse::default();
 
     let (shards, _other_keys) =
-        list_remote_tenant_shards(remote_storage, tenant_id, cancel.clone())
+        list_remote_tenant_shards(&state.remote_storage, tenant_id, cancel.clone())
             .await
             .map_err(|e| ApiError::InternalServerError(anyhow::anyhow!(e)))?;
 
     for tenant_shard_id in shards {
         let (timeline_ids, _other_keys) =
-            list_remote_timelines(remote_storage, tenant_shard_id, cancel.clone())
+            list_remote_timelines(&state.remote_storage, tenant_shard_id, cancel.clone())
                 .await
                 .map_err(|e| ApiError::InternalServerError(anyhow::anyhow!(e)))?;
 
         let mut generation = Generation::none();
         for timeline_id in timeline_ids {
             match download_index_part(
-                remote_storage,
+                &state.remote_storage,
                 &tenant_shard_id,
                 &timeline_id,
                 Generation::MAX,
@@ -2160,6 +2210,27 @@ async fn secondary_download_handler(
     json_response(status, progress)
 }
 
+async fn secondary_status_handler(
+    request: Request<Body>,
+    _cancel: CancellationToken,
+) -> Result<Response<Body>, ApiError> {
+    let state = get_state(&request);
+    let tenant_shard_id: TenantShardId = parse_request_param(&request, "tenant_shard_id")?;
+
+    let Some(secondary_tenant) = state
+        .tenant_manager
+        .get_secondary_tenant_shard(tenant_shard_id)
+    else {
+        return Err(ApiError::NotFound(
+            anyhow::anyhow!("Shard {} not found", tenant_shard_id).into(),
+        ));
+    };
+
+    let progress = secondary_tenant.progress.lock().unwrap().clone();
+
+    json_response(StatusCode::OK, progress)
+}
+
 async fn handler_404(_: Request<Body>) -> Result<Response<Body>, ApiError> {
     json_response(
         StatusCode::NOT_FOUND,
@@ -2262,6 +2333,162 @@ async fn get_utilization(
         .map_err(ApiError::InternalServerError)
 }
 
+async fn list_aux_files(
+    mut request: Request<Body>,
+    _cancel: CancellationToken,
+) -> Result<Response<Body>, ApiError> {
+    let tenant_shard_id: TenantShardId = parse_request_param(&request, "tenant_shard_id")?;
+    let timeline_id: TimelineId = parse_request_param(&request, "timeline_id")?;
+    let body: ListAuxFilesRequest = json_request(&mut request).await?;
+    check_permission(&request, Some(tenant_shard_id.tenant_id))?;
+
+    let state = get_state(&request);
+
+    let timeline =
+        active_timeline_of_active_tenant(&state.tenant_manager, tenant_shard_id, timeline_id)
+            .await?;
+
+    let process = || async move {
+        let ctx = RequestContext::new(TaskKind::MgmtRequest, DownloadBehavior::Download);
+        let files = timeline.list_aux_files(body.lsn, &ctx).await?;
+        Ok::<_, anyhow::Error>(files)
+    };
+
+    match process().await {
+        Ok(st) => json_response(StatusCode::OK, st),
+        Err(err) => json_response(
+            StatusCode::INTERNAL_SERVER_ERROR,
+            ApiError::InternalServerError(err).to_string(),
+        ),
+    }
+}
+
+async fn ingest_aux_files(
+    mut request: Request<Body>,
+    _cancel: CancellationToken,
+) -> Result<Response<Body>, ApiError> {
+    let tenant_shard_id: TenantShardId = parse_request_param(&request, "tenant_shard_id")?;
+    let timeline_id: TimelineId = parse_request_param(&request, "timeline_id")?;
+    let body: IngestAuxFilesRequest = json_request(&mut request).await?;
+    check_permission(&request, Some(tenant_shard_id.tenant_id))?;
+
+    let state = get_state(&request);
+
+    let timeline =
+        active_timeline_of_active_tenant(&state.tenant_manager, tenant_shard_id, timeline_id)
+            .await?;
+
+    let process = || async move {
+        let mut modification = timeline.begin_modification(Lsn(
+            timeline.get_last_record_lsn().0 + 8
+        ) /* advance LSN by 8 */);
+        let ctx = RequestContext::new(TaskKind::MgmtRequest, DownloadBehavior::Download);
+        for (fname, content) in body.aux_files {
+            modification
+                .put_file(&fname, content.as_bytes(), &ctx)
+                .await?;
+        }
+        modification.commit(&ctx).await?;
+        Ok::<_, anyhow::Error>(())
+    };
+
+    match process().await {
+        Ok(st) => json_response(StatusCode::OK, st),
+        Err(err) => Err(ApiError::InternalServerError(err)),
+    }
+}
+
+/// Report on the largest tenants on this pageserver, for the storage controller to identify
+/// candidates for splitting
+async fn post_top_tenants(
+    mut r: Request<Body>,
+    _cancel: CancellationToken,
+) -> Result<Response<Body>, ApiError> {
+    check_permission(&r, None)?;
+    let request: TopTenantShardsRequest = json_request(&mut r).await?;
+    let state = get_state(&r);
+
+    fn get_size_metric(sizes: &TopTenantShardItem, order_by: &TenantSorting) -> u64 {
+        match order_by {
+            TenantSorting::ResidentSize => sizes.resident_size,
+            TenantSorting::MaxLogicalSize => sizes.max_logical_size,
+        }
+    }
+
+    #[derive(Eq, PartialEq)]
+    struct HeapItem {
+        metric: u64,
+        sizes: TopTenantShardItem,
+    }
+
+    impl PartialOrd for HeapItem {
+        fn partial_cmp(&self, other: &Self) -> Option<std::cmp::Ordering> {
+            Some(self.cmp(other))
+        }
+    }
+
+    /// Heap items have reverse ordering on their metric: this enables using BinaryHeap, which
+    /// supports popping the greatest item but not the smallest.
+    impl Ord for HeapItem {
+        fn cmp(&self, other: &Self) -> std::cmp::Ordering {
+            Reverse(self.metric).cmp(&Reverse(other.metric))
+        }
+    }
+
+    let mut top_n: BinaryHeap<HeapItem> = BinaryHeap::with_capacity(request.limit);
+
+    // FIXME: this is a lot of clones to take this tenant list
+    for (tenant_shard_id, tenant_slot) in state.tenant_manager.list() {
+        if let Some(shards_lt) = request.where_shards_lt {
+            // Ignore tenants which already have >= this many shards
+            if tenant_shard_id.shard_count >= shards_lt {
+                continue;
+            }
+        }
+
+        let sizes = match tenant_slot {
+            TenantSlot::Attached(tenant) => tenant.get_sizes(),
+            TenantSlot::Secondary(_) | TenantSlot::InProgress(_) => {
+                continue;
+            }
+        };
+        let metric = get_size_metric(&sizes, &request.order_by);
+
+        if let Some(gt) = request.where_gt {
+            // Ignore tenants whose metric is <= the lower size threshold, to do less sorting work
+            if metric <= gt {
+                continue;
+            }
+        };
+
+        match top_n.peek() {
+            None => {
+                // Top N list is empty: candidate becomes first member
+                top_n.push(HeapItem { metric, sizes });
+            }
+            Some(i) if i.metric > metric && top_n.len() < request.limit => {
+                // Lowest item in list is greater than our candidate, but we aren't at limit yet: push to end
+                top_n.push(HeapItem { metric, sizes });
+            }
+            Some(i) if i.metric > metric => {
+                // List is at limit and lowest value is greater than our candidate, drop it.
+            }
+            Some(_) => top_n.push(HeapItem { metric, sizes }),
+        }
+
+        while top_n.len() > request.limit {
+            top_n.pop();
+        }
+    }
+
+    json_response(
+        StatusCode::OK,
+        TopTenantShardsResponse {
+            shards: top_n.into_iter().map(|i| i.sizes).collect(),
+        },
+    )
+}
+
 /// Common functionality of all the HTTP API handlers.
 ///
 /// - Adds a tracing span to each request (by `request_span`)
@@ -2494,6 +2721,10 @@ pub fn make_router(
             "/v1/tenant/:tenant_shard_id/timeline/:timeline_id/download_remote_layers",
             |r| api_handler(r, timeline_download_remote_layers_handler_get),
         )
+        .put(
+            "/v1/tenant/:tenant_shard_id/timeline/:timeline_id/detach_ancestor",
+            |r| api_handler(r, timeline_detach_ancestor_handler),
+        )
         .delete("/v1/tenant/:tenant_shard_id/timeline/:timeline_id", |r| {
             api_handler(r, timeline_delete_handler)
         })
@@ -2521,6 +2752,9 @@ pub fn make_router(
         .put("/v1/deletion_queue/flush", |r| {
             api_handler(r, deletion_queue_flush)
         })
+        .get("/v1/tenant/:tenant_shard_id/secondary/status", |r| {
+            api_handler(r, secondary_status_handler)
+        })
         .post("/v1/tenant/:tenant_shard_id/secondary/download", |r| {
             api_handler(r, secondary_download_handler)
         })
@@ -2541,5 +2775,14 @@ pub fn make_router(
         )
         .put("/v1/io_engine", |r| api_handler(r, put_io_engine_handler))
         .get("/v1/utilization", |r| api_handler(r, get_utilization))
+        .post(
+            "/v1/tenant/:tenant_shard_id/timeline/:timeline_id/ingest_aux_files",
+            |r| testing_api_handler("ingest_aux_files", r, ingest_aux_files),
+        )
+        .post(
+            "/v1/tenant/:tenant_shard_id/timeline/:timeline_id/list_aux_files",
+            |r| testing_api_handler("list_aux_files", r, list_aux_files),
+        )
+        .post("/v1/top_tenants", |r| api_handler(r, post_top_tenants))
         .any(handler_404))
 }

pageserver/src/lib.rs

@@ -57,7 +57,7 @@ pub use crate::metrics::preinitialize_metrics;
 #[tracing::instrument(skip_all, fields(%exit_code))]
 pub async fn shutdown_pageserver(
     tenant_manager: &TenantManager,
-    deletion_queue: Option<DeletionQueue>,
+    mut deletion_queue: DeletionQueue,
     exit_code: i32,
 ) {
     use std::time::Duration;
@@ -89,9 +89,7 @@ pub async fn shutdown_pageserver(
     .await;
 
     // Best effort to persist any outstanding deletions, to avoid leaking objects
-    if let Some(mut deletion_queue) = deletion_queue {
-        deletion_queue.shutdown(Duration::from_secs(5)).await;
-    }
+    deletion_queue.shutdown(Duration::from_secs(5)).await;
 
     // Shut down the HTTP endpoint last, so that you can still check the server's
     // status while it's shutting down.
@@ -114,10 +112,6 @@ pub async fn shutdown_pageserver(
     std::process::exit(exit_code);
 }
 
-/// The name of the metadata file pageserver creates per timeline.
-/// Full path: `tenants/<tenant_id>/timelines/<timeline_id>/metadata`.
-pub const METADATA_FILE_NAME: &str = "metadata";
-
 /// Per-tenant configuration file.
 /// Full path: `tenants/<tenant_id>/config`.
 pub(crate) const TENANT_CONFIG_NAME: &str = "config";

pageserver/src/metrics.rs

@@ -51,8 +51,8 @@ pub(crate) enum StorageTimeOperation {
     #[strum(serialize = "gc")]
     Gc,
 
-    #[strum(serialize = "update gc info")]
-    UpdateGcInfo,
+    #[strum(serialize = "find gc cutoffs")]
+    FindGcCutoffs,
 
     #[strum(serialize = "create tenant")]
     CreateTenant,
@@ -194,6 +194,11 @@ pub(crate) struct GetVectoredLatency {
     map: EnumMap<TaskKind, Option<Histogram>>,
 }
 
+#[allow(dead_code)]
+pub(crate) struct ScanLatency {
+    map: EnumMap<TaskKind, Option<Histogram>>,
+}
+
 impl GetVectoredLatency {
     // Only these task types perform vectored gets. Filter all other tasks out to reduce total
     // cardinality of the metric.
@@ -204,6 +209,48 @@ impl GetVectoredLatency {
     }
 }
 
+impl ScanLatency {
+    // Only these task types perform vectored gets. Filter all other tasks out to reduce total
+    // cardinality of the metric.
+    const TRACKED_TASK_KINDS: [TaskKind; 1] = [TaskKind::PageRequestHandler];
+
+    pub(crate) fn for_task_kind(&self, task_kind: TaskKind) -> Option<&Histogram> {
+        self.map[task_kind].as_ref()
+    }
+}
+
+pub(crate) struct ScanLatencyOngoingRecording<'a> {
+    parent: &'a Histogram,
+    start: std::time::Instant,
+}
+
+impl<'a> ScanLatencyOngoingRecording<'a> {
+    pub(crate) fn start_recording(parent: &'a Histogram) -> ScanLatencyOngoingRecording<'a> {
+        let start = Instant::now();
+        ScanLatencyOngoingRecording { parent, start }
+    }
+
+    pub(crate) fn observe(self, throttled: Option<Duration>) {
+        let elapsed = self.start.elapsed();
+        let ex_throttled = if let Some(throttled) = throttled {
+            elapsed.checked_sub(throttled)
+        } else {
+            Some(elapsed)
+        };
+        if let Some(ex_throttled) = ex_throttled {
+            self.parent.observe(ex_throttled.as_secs_f64());
+        } else {
+            use utils::rate_limit::RateLimit;
+            static LOGGED: Lazy<Mutex<RateLimit>> =
+                Lazy::new(|| Mutex::new(RateLimit::new(Duration::from_secs(10))));
+            let mut rate_limit = LOGGED.lock().unwrap();
+            rate_limit.call(|| {
+                warn!("error deducting time spent throttled; this message is logged at a global rate limit");
+            });
+        }
+    }
+}
+
 pub(crate) static GET_VECTORED_LATENCY: Lazy<GetVectoredLatency> = Lazy::new(|| {
     let inner = register_histogram_vec!(
         "pageserver_get_vectored_seconds",
@@ -227,6 +274,29 @@ pub(crate) static GET_VECTORED_LATENCY: Lazy<GetVectoredLatency> = Lazy::new(||
     }
 });
 
+pub(crate) static SCAN_LATENCY: Lazy<ScanLatency> = Lazy::new(|| {
+    let inner = register_histogram_vec!(
+        "pageserver_scan_seconds",
+        "Time spent in scan, excluding time spent in timeline_get_throttle.",
+        &["task_kind"],
+        CRITICAL_OP_BUCKETS.into(),
+    )
+    .expect("failed to define a metric");
+
+    ScanLatency {
+        map: EnumMap::from_array(std::array::from_fn(|task_kind_idx| {
+            let task_kind = <TaskKind as enum_map::Enum>::from_usize(task_kind_idx);
+
+            if ScanLatency::TRACKED_TASK_KINDS.contains(&task_kind) {
+                let task_kind = task_kind.into();
+                Some(inner.with_label_values(&[task_kind]))
+            } else {
+                None
+            }
+        })),
+    }
+});
+
 pub(crate) struct PageCacheMetricsForTaskKind {
     pub read_accesses_materialized_page: IntCounter,
     pub read_accesses_immutable: IntCounter,
@@ -515,6 +585,15 @@ static CURRENT_LOGICAL_SIZE: Lazy<UIntGaugeVec> = Lazy::new(|| {
     .expect("failed to define current logical size metric")
 });
 
+static AUX_FILE_SIZE: Lazy<IntGaugeVec> = Lazy::new(|| {
+    register_int_gauge_vec!(
+        "pageserver_aux_file_estimated_size",
+        "The size of all aux files for a timeline in aux file v2 store.",
+        &["tenant_id", "shard_id", "timeline_id"]
+    )
+    .expect("failed to define a metric")
+});
+
 pub(crate) mod initial_logical_size {
     use metrics::{register_int_counter, register_int_counter_vec, IntCounter, IntCounterVec};
     use once_cell::sync::Lazy;
@@ -1442,29 +1521,80 @@ static REMOTE_TIMELINE_CLIENT_BYTES_FINISHED_COUNTER: Lazy<IntCounterVec> = Lazy
 });
 
 pub(crate) struct TenantManagerMetrics {
-    pub(crate) tenant_slots: UIntGauge,
+    tenant_slots_attached: UIntGauge,
+    tenant_slots_secondary: UIntGauge,
+    tenant_slots_inprogress: UIntGauge,
     pub(crate) tenant_slot_writes: IntCounter,
     pub(crate) unexpected_errors: IntCounter,
 }
 
+impl TenantManagerMetrics {
+    /// Helpers for tracking slots.  Note that these do not track the lifetime of TenantSlot objects
+    /// exactly: they track the lifetime of the slots _in the tenant map_.
+    pub(crate) fn slot_inserted(&self, slot: &TenantSlot) {
+        match slot {
+            TenantSlot::Attached(_) => {
+                self.tenant_slots_attached.inc();
+            }
+            TenantSlot::Secondary(_) => {
+                self.tenant_slots_secondary.inc();
+            }
+            TenantSlot::InProgress(_) => {
+                self.tenant_slots_inprogress.inc();
+            }
+        }
+    }
+
+    pub(crate) fn slot_removed(&self, slot: &TenantSlot) {
+        match slot {
+            TenantSlot::Attached(_) => {
+                self.tenant_slots_attached.dec();
+            }
+            TenantSlot::Secondary(_) => {
+                self.tenant_slots_secondary.dec();
+            }
+            TenantSlot::InProgress(_) => {
+                self.tenant_slots_inprogress.dec();
+            }
+        }
+    }
+
+    #[cfg(all(debug_assertions, not(test)))]
+    pub(crate) fn slots_total(&self) -> u64 {
+        self.tenant_slots_attached.get()
+            + self.tenant_slots_secondary.get()
+            + self.tenant_slots_inprogress.get()
+    }
+}
+
 pub(crate) static TENANT_MANAGER: Lazy<TenantManagerMetrics> = Lazy::new(|| {
-    TenantManagerMetrics {
-    tenant_slots: register_uint_gauge!(
+    let tenant_slots = register_uint_gauge_vec!(
         "pageserver_tenant_manager_slots",
         "How many slots currently exist, including all attached, secondary and in-progress operations",
+        &["mode"]
     )
-    .expect("failed to define a metric"),
-    tenant_slot_writes: register_int_counter!(
-        "pageserver_tenant_manager_slot_writes",
-        "Writes to a tenant slot, including all of create/attach/detach/delete"
-    )
-    .expect("failed to define a metric"),
-    unexpected_errors: register_int_counter!(
-        "pageserver_tenant_manager_unexpected_errors_total",
-        "Number of unexpected conditions encountered: nonzero value indicates a non-fatal bug."
-    )
-    .expect("failed to define a metric"),
-}
+    .expect("failed to define a metric");
+    TenantManagerMetrics {
+        tenant_slots_attached: tenant_slots
+            .get_metric_with_label_values(&["attached"])
+            .unwrap(),
+        tenant_slots_secondary: tenant_slots
+            .get_metric_with_label_values(&["secondary"])
+            .unwrap(),
+        tenant_slots_inprogress: tenant_slots
+            .get_metric_with_label_values(&["inprogress"])
+            .unwrap(),
+        tenant_slot_writes: register_int_counter!(
+            "pageserver_tenant_manager_slot_writes",
+            "Writes to a tenant slot, including all of create/attach/detach/delete"
+        )
+        .expect("failed to define a metric"),
+        unexpected_errors: register_int_counter!(
+            "pageserver_tenant_manager_unexpected_errors_total",
+            "Number of unexpected conditions encountered: nonzero value indicates a non-fatal bug."
+        )
+        .expect("failed to define a metric"),
+    }
 });
 
 pub(crate) struct DeletionQueueMetrics {
@@ -1869,29 +1999,6 @@ impl Default for WalRedoProcessCounters {
 pub(crate) static WAL_REDO_PROCESS_COUNTERS: Lazy<WalRedoProcessCounters> =
     Lazy::new(WalRedoProcessCounters::default);
 
-#[cfg(not(test))]
-pub mod wal_redo {
-    use super::*;
-
-    static PROCESS_KIND: Lazy<std::sync::Mutex<UIntGaugeVec>> = Lazy::new(|| {
-        std::sync::Mutex::new(
-            register_uint_gauge_vec!(
-                "pageserver_wal_redo_process_kind",
-                "The configured process kind for walredo",
-                &["kind"],
-            )
-            .unwrap(),
-        )
-    });
-
-    pub fn set_process_kind_metric(kind: crate::walredo::ProcessKind) {
-        // use guard to avoid races around the next two steps
-        let guard = PROCESS_KIND.lock().unwrap();
-        guard.reset();
-        guard.with_label_values(&[&format!("{kind}")]).set(1);
-    }
-}
-
 /// Similar to `prometheus::HistogramTimer` but does not record on drop.
 pub(crate) struct StorageTimeMetricsTimer {
     metrics: StorageTimeMetrics,
@@ -1989,11 +2096,12 @@ pub(crate) struct TimelineMetrics {
     pub imitate_logical_size_histo: StorageTimeMetrics,
     pub load_layer_map_histo: StorageTimeMetrics,
     pub garbage_collect_histo: StorageTimeMetrics,
-    pub update_gc_info_histo: StorageTimeMetrics,
+    pub find_gc_cutoffs_histo: StorageTimeMetrics,
     pub last_record_gauge: IntGauge,
-    resident_physical_size_gauge: UIntGauge,
+    pub resident_physical_size_gauge: UIntGauge,
     /// copy of LayeredTimeline.current_logical_size
     pub current_logical_size_gauge: UIntGauge,
+    pub aux_file_size_gauge: IntGauge,
     pub directory_entries_count_gauge: Lazy<UIntGauge, Box<dyn Send + Fn() -> UIntGauge>>,
     pub evictions: IntCounter,
     pub evictions_with_low_residence_duration: std::sync::RwLock<EvictionsWithLowResidenceDuration>,
@@ -2050,8 +2158,8 @@ impl TimelineMetrics {
             &shard_id,
             &timeline_id,
         );
-        let update_gc_info_histo = StorageTimeMetrics::new(
-            StorageTimeOperation::UpdateGcInfo,
+        let find_gc_cutoffs_histo = StorageTimeMetrics::new(
+            StorageTimeOperation::FindGcCutoffs,
             &tenant_id,
             &shard_id,
             &timeline_id,
@@ -2066,6 +2174,9 @@ impl TimelineMetrics {
         let current_logical_size_gauge = CURRENT_LOGICAL_SIZE
             .get_metric_with_label_values(&[&tenant_id, &shard_id, &timeline_id])
             .unwrap();
+        let aux_file_size_gauge = AUX_FILE_SIZE
+            .get_metric_with_label_values(&[&tenant_id, &shard_id, &timeline_id])
+            .unwrap();
         // TODO use impl Trait syntax here once we have ability to use it: https://github.com/rust-lang/rust/issues/63065
         let directory_entries_count_gauge_closure = {
             let tenant_shard_id = *tenant_shard_id;
@@ -2098,11 +2209,12 @@ impl TimelineMetrics {
             logical_size_histo,
             imitate_logical_size_histo,
             garbage_collect_histo,
-            update_gc_info_histo,
+            find_gc_cutoffs_histo,
             load_layer_map_histo,
             last_record_gauge,
             resident_physical_size_gauge,
             current_logical_size_gauge,
+            aux_file_size_gauge,
             directory_entries_count_gauge,
             evictions,
             evictions_with_low_residence_duration: std::sync::RwLock::new(
@@ -2143,6 +2255,7 @@ impl TimelineMetrics {
             let _ = metric.remove_label_values(&[tenant_id, shard_id, timeline_id]);
         }
         let _ = EVICTIONS.remove_label_values(&[tenant_id, shard_id, timeline_id]);
+        let _ = AUX_FILE_SIZE.remove_label_values(&[tenant_id, shard_id, timeline_id]);
 
         self.evictions_with_low_residence_duration
             .write()
@@ -2199,43 +2312,45 @@ use pin_project_lite::pin_project;
 use std::collections::HashMap;
 use std::num::NonZeroUsize;
 use std::pin::Pin;
+use std::sync::atomic::AtomicU64;
 use std::sync::{Arc, Mutex};
 use std::task::{Context, Poll};
 use std::time::{Duration, Instant};
 
 use crate::context::{PageContentKind, RequestContext};
 use crate::task_mgr::TaskKind;
+use crate::tenant::mgr::TenantSlot;
 
 /// Maintain a per timeline gauge in addition to the global gauge.
-struct PerTimelineRemotePhysicalSizeGauge {
-    last_set: u64,
+pub(crate) struct PerTimelineRemotePhysicalSizeGauge {
+    last_set: AtomicU64,
     gauge: UIntGauge,
 }
 
 impl PerTimelineRemotePhysicalSizeGauge {
     fn new(per_timeline_gauge: UIntGauge) -> Self {
         Self {
-            last_set: per_timeline_gauge.get(),
+            last_set: AtomicU64::new(0),
             gauge: per_timeline_gauge,
         }
     }
-    fn set(&mut self, sz: u64) {
+    pub(crate) fn set(&self, sz: u64) {
         self.gauge.set(sz);
-        if sz < self.last_set {
-            REMOTE_PHYSICAL_SIZE_GLOBAL.sub(self.last_set - sz);
+        let prev = self.last_set.swap(sz, std::sync::atomic::Ordering::Relaxed);
+        if sz < prev {
+            REMOTE_PHYSICAL_SIZE_GLOBAL.sub(prev - sz);
         } else {
-            REMOTE_PHYSICAL_SIZE_GLOBAL.add(sz - self.last_set);
+            REMOTE_PHYSICAL_SIZE_GLOBAL.add(sz - prev);
         };
-        self.last_set = sz;
     }
-    fn get(&self) -> u64 {
+    pub(crate) fn get(&self) -> u64 {
         self.gauge.get()
     }
 }
 
 impl Drop for PerTimelineRemotePhysicalSizeGauge {
     fn drop(&mut self) {
-        REMOTE_PHYSICAL_SIZE_GLOBAL.sub(self.last_set);
+        REMOTE_PHYSICAL_SIZE_GLOBAL.sub(self.last_set.load(std::sync::atomic::Ordering::Relaxed));
     }
 }
 
@@ -2243,7 +2358,7 @@ pub(crate) struct RemoteTimelineClientMetrics {
     tenant_id: String,
     shard_id: String,
     timeline_id: String,
-    remote_physical_size_gauge: Mutex<Option<PerTimelineRemotePhysicalSizeGauge>>,
+    pub(crate) remote_physical_size_gauge: PerTimelineRemotePhysicalSizeGauge,
     calls: Mutex<HashMap<(&'static str, &'static str), IntCounterPair>>,
     bytes_started_counter: Mutex<HashMap<(&'static str, &'static str), IntCounter>>,
     bytes_finished_counter: Mutex<HashMap<(&'static str, &'static str), IntCounter>>,
@@ -2251,38 +2366,27 @@ pub(crate) struct RemoteTimelineClientMetrics {
 
 impl RemoteTimelineClientMetrics {
     pub fn new(tenant_shard_id: &TenantShardId, timeline_id: &TimelineId) -> Self {
+        let tenant_id_str = tenant_shard_id.tenant_id.to_string();
+        let shard_id_str = format!("{}", tenant_shard_id.shard_slug());
+        let timeline_id_str = timeline_id.to_string();
+
+        let remote_physical_size_gauge = PerTimelineRemotePhysicalSizeGauge::new(
+            REMOTE_PHYSICAL_SIZE
+                .get_metric_with_label_values(&[&tenant_id_str, &shard_id_str, &timeline_id_str])
+                .unwrap(),
+        );
+
         RemoteTimelineClientMetrics {
-            tenant_id: tenant_shard_id.tenant_id.to_string(),
-            shard_id: format!("{}", tenant_shard_id.shard_slug()),
-            timeline_id: timeline_id.to_string(),
+            tenant_id: tenant_id_str,
+            shard_id: shard_id_str,
+            timeline_id: timeline_id_str,
             calls: Mutex::new(HashMap::default()),
             bytes_started_counter: Mutex::new(HashMap::default()),
             bytes_finished_counter: Mutex::new(HashMap::default()),
-            remote_physical_size_gauge: Mutex::new(None),
+            remote_physical_size_gauge,
         }
     }
 
-    pub(crate) fn remote_physical_size_set(&self, sz: u64) {
-        let mut guard = self.remote_physical_size_gauge.lock().unwrap();
-        let gauge = guard.get_or_insert_with(|| {
-            PerTimelineRemotePhysicalSizeGauge::new(
-                REMOTE_PHYSICAL_SIZE
-                    .get_metric_with_label_values(&[
-                        &self.tenant_id,
-                        &self.shard_id,
-                        &self.timeline_id,
-                    ])
-                    .unwrap(),
-            )
-        });
-        gauge.set(sz);
-    }
-
-    pub(crate) fn remote_physical_size_get(&self) -> u64 {
-        let guard = self.remote_physical_size_gauge.lock().unwrap();
-        guard.as_ref().map(|gauge| gauge.get()).unwrap_or(0)
-    }
-
     pub fn remote_operation_time(
         &self,
         file_kind: &RemoteOpFileKind,
@@ -2807,6 +2911,8 @@ pub fn preinitialize_metrics() {
         &WALRECEIVER_CANDIDATES_REMOVED,
         &tokio_epoll_uring::THREAD_LOCAL_LAUNCH_FAILURES,
         &tokio_epoll_uring::THREAD_LOCAL_LAUNCH_SUCCESSES,
+        &REMOTE_ONDEMAND_DOWNLOADED_LAYERS,
+        &REMOTE_ONDEMAND_DOWNLOADED_BYTES,
     ]
     .into_iter()
     .for_each(|c| {

pageserver/src/page_service.rs

@@ -32,6 +32,7 @@ use std::str;
 use std::str::FromStr;
 use std::sync::Arc;
 use std::time::Duration;
+use std::time::Instant;
 use tokio::io::AsyncWriteExt;
 use tokio::io::{AsyncRead, AsyncWrite};
 use tokio_util::io::StreamReader;
@@ -49,7 +50,6 @@ use utils::{
 use crate::auth::check_permission;
 use crate::basebackup;
 use crate::basebackup::BasebackupError;
-use crate::config::PageServerConf;
 use crate::context::{DownloadBehavior, RequestContext};
 use crate::import_datadir::import_wal_from_tar;
 use crate::metrics;
@@ -59,13 +59,15 @@ use crate::span::debug_assert_current_span_has_tenant_and_timeline_id;
 use crate::span::debug_assert_current_span_has_tenant_and_timeline_id_no_shard_id;
 use crate::task_mgr;
 use crate::task_mgr::TaskKind;
-use crate::tenant::mgr;
-use crate::tenant::mgr::get_active_tenant_with_timeout;
 use crate::tenant::mgr::GetActiveTenantError;
+use crate::tenant::mgr::GetTenantError;
+use crate::tenant::mgr::ShardResolveResult;
 use crate::tenant::mgr::ShardSelector;
+use crate::tenant::mgr::TenantManager;
 use crate::tenant::timeline::WaitLsnError;
 use crate::tenant::GetTimelineError;
 use crate::tenant::PageReconstructError;
+use crate::tenant::Tenant;
 use crate::tenant::Timeline;
 use crate::trace::Tracer;
 use pageserver_api::key::rel_block_to_key;
@@ -135,7 +137,7 @@ async fn read_tar_eof(mut reader: (impl AsyncRead + Unpin)) -> anyhow::Result<()
 /// Listens for connections, and launches a new handler task for each.
 ///
 pub async fn libpq_listener_main(
-    conf: &'static PageServerConf,
+    tenant_manager: Arc<TenantManager>,
     broker_client: storage_broker::BrokerClientChannel,
     auth: Option<Arc<SwappableJwtAuth>>,
     listener: TcpListener,
@@ -180,7 +182,7 @@ pub async fn libpq_listener_main(
                     "serving compute connection task",
                     false,
                     page_service_conn_main(
-                        conf,
+                        tenant_manager.clone(),
                         broker_client.clone(),
                         local_auth,
                         socket,
@@ -203,7 +205,7 @@ pub async fn libpq_listener_main(
 
 #[instrument(skip_all, fields(peer_addr))]
 async fn page_service_conn_main(
-    conf: &'static PageServerConf,
+    tenant_manager: Arc<TenantManager>,
     broker_client: storage_broker::BrokerClientChannel,
     auth: Option<Arc<SwappableJwtAuth>>,
     socket: tokio::net::TcpStream,
@@ -260,7 +262,8 @@ async fn page_service_conn_main(
     // and create a child per-query context when it invokes process_query.
     // But it's in a shared crate, so, we store connection_ctx inside PageServerHandler
     // and create the per-query context in process_query ourselves.
-    let mut conn_handler = PageServerHandler::new(conf, broker_client, auth, connection_ctx);
+    let mut conn_handler =
+        PageServerHandler::new(tenant_manager, broker_client, auth, connection_ctx);
     let pgbackend = PostgresBackend::new_from_io(socket, peer_addr, auth_type, None)?;
 
     match pgbackend
@@ -291,11 +294,12 @@ struct HandlerTimeline {
 }
 
 struct PageServerHandler {
-    _conf: &'static PageServerConf,
     broker_client: storage_broker::BrokerClientChannel,
     auth: Option<Arc<SwappableJwtAuth>>,
     claims: Option<Claims>,
 
+    tenant_manager: Arc<TenantManager>,
+
     /// The context created for the lifetime of the connection
     /// services by this PageServerHandler.
     /// For each query received over the connection,
@@ -381,13 +385,13 @@ impl From<WaitLsnError> for QueryError {
 
 impl PageServerHandler {
     pub fn new(
-        conf: &'static PageServerConf,
+        tenant_manager: Arc<TenantManager>,
         broker_client: storage_broker::BrokerClientChannel,
         auth: Option<Arc<SwappableJwtAuth>>,
         connection_ctx: RequestContext,
     ) -> Self {
         PageServerHandler {
-            _conf: conf,
+            tenant_manager,
             broker_client,
             auth,
             claims: None,
@@ -552,13 +556,9 @@ impl PageServerHandler {
     {
         debug_assert_current_span_has_tenant_and_timeline_id_no_shard_id();
 
-        let tenant = mgr::get_active_tenant_with_timeout(
-            tenant_id,
-            ShardSelector::First,
-            ACTIVE_TENANT_TIMEOUT,
-            &task_mgr::shutdown_token(),
-        )
-        .await?;
+        let tenant = self
+            .get_active_tenant_with_timeout(tenant_id, ShardSelector::First, ACTIVE_TENANT_TIMEOUT)
+            .await?;
 
         // Make request tracer if needed
         let mut tracer = if tenant.get_trace_read_requests() {
@@ -726,13 +726,9 @@ impl PageServerHandler {
 
         // Create empty timeline
         info!("creating new timeline");
-        let tenant = get_active_tenant_with_timeout(
-            tenant_id,
-            ShardSelector::Zero,
-            ACTIVE_TENANT_TIMEOUT,
-            &task_mgr::shutdown_token(),
-        )
-        .await?;
+        let tenant = self
+            .get_active_tenant_with_timeout(tenant_id, ShardSelector::Zero, ACTIVE_TENANT_TIMEOUT)
+            .await?;
         let timeline = tenant
             .create_empty_timeline(timeline_id, base_lsn, pg_version, &ctx)
             .await?;
@@ -1370,18 +1366,69 @@ impl PageServerHandler {
         timeline_id: TimelineId,
         selector: ShardSelector,
     ) -> Result<Arc<Timeline>, GetActiveTimelineError> {
-        let tenant = get_active_tenant_with_timeout(
-            tenant_id,
-            selector,
-            ACTIVE_TENANT_TIMEOUT,
-            &task_mgr::shutdown_token(),
-        )
-        .await
-        .map_err(GetActiveTimelineError::Tenant)?;
+        let tenant = self
+            .get_active_tenant_with_timeout(tenant_id, selector, ACTIVE_TENANT_TIMEOUT)
+            .await
+            .map_err(GetActiveTimelineError::Tenant)?;
         let timeline = tenant.get_timeline(timeline_id, true)?;
         set_tracing_field_shard_id(&timeline);
         Ok(timeline)
     }
+
+    /// Get a shard's [`Tenant`] in its active state, if present.  If we don't find the shard and some
+    /// slots for this tenant are `InProgress` then we will wait.
+    /// If we find the [`Tenant`] and it's not yet in state [`TenantState::Active`], we will wait.
+    ///
+    /// `timeout` is used as a total timeout for the whole wait operation.
+    async fn get_active_tenant_with_timeout(
+        &self,
+        tenant_id: TenantId,
+        shard_selector: ShardSelector,
+        timeout: Duration,
+    ) -> Result<Arc<Tenant>, GetActiveTenantError> {
+        let wait_start = Instant::now();
+        let deadline = wait_start + timeout;
+
+        // Resolve TenantId to TenantShardId.  This is usually a quick one-shot thing, the loop is
+        // for handling the rare case that the slot we're accessing is InProgress.
+        let tenant_shard = loop {
+            let resolved = self
+                .tenant_manager
+                .resolve_attached_shard(&tenant_id, shard_selector);
+            match resolved {
+                ShardResolveResult::Found(tenant_shard) => break tenant_shard,
+                ShardResolveResult::NotFound => {
+                    return Err(GetActiveTenantError::NotFound(GetTenantError::NotFound(
+                        tenant_id,
+                    )));
+                }
+                ShardResolveResult::InProgress(barrier) => {
+                    // We can't authoritatively answer right now: wait for InProgress state
+                    // to end, then try again
+                    tokio::select! {
+                        _ = self.await_connection_cancelled() => {
+                            return Err(GetActiveTenantError::Cancelled)
+                        },
+                        _  = barrier.wait() => {
+                            // The barrier completed: proceed around the loop to try looking up again
+                        },
+                        _ = tokio::time::sleep(deadline.duration_since(Instant::now())) => {
+                            return Err(GetActiveTenantError::WaitForActiveTimeout {
+                                latest_state: None,
+                                wait_time: timeout,
+                            });
+                        }
+                    }
+                }
+            };
+        };
+
+        tracing::debug!("Waiting for tenant to enter active state...");
+        tenant_shard
+            .wait_to_become_active(deadline.duration_since(Instant::now()))
+            .await?;
+        Ok(tenant_shard)
+    }
 }
 
 #[async_trait::async_trait]
@@ -1771,13 +1818,13 @@ where
 
             self.check_permission(Some(tenant_id))?;
 
-            let tenant = get_active_tenant_with_timeout(
-                tenant_id,
-                ShardSelector::Zero,
-                ACTIVE_TENANT_TIMEOUT,
-                &task_mgr::shutdown_token(),
-            )
-            .await?;
+            let tenant = self
+                .get_active_tenant_with_timeout(
+                    tenant_id,
+                    ShardSelector::Zero,
+                    ACTIVE_TENANT_TIMEOUT,
+                )
+                .await?;
             pgb.write_message_noflush(&BeMessage::RowDescription(&[
                 RowDescriptor::int8_col(b"checkpoint_distance"),
                 RowDescriptor::int8_col(b"checkpoint_timeout"),

pageserver/src/pgdatadir_mapping.rs

@@ -10,9 +10,9 @@ use super::tenant::{PageReconstructError, Timeline};
 use crate::context::RequestContext;
 use crate::keyspace::{KeySpace, KeySpaceAccum};
 use crate::metrics::WAL_INGEST;
-use crate::repository::*;
 use crate::span::debug_assert_current_span_has_tenant_and_timeline_id_no_shard_id;
 use crate::walrecord::NeonWalRecord;
+use crate::{aux_file, repository::*};
 use anyhow::{ensure, Context};
 use bytes::{Buf, Bytes, BytesMut};
 use enum_map::Enum;
@@ -24,6 +24,7 @@ use pageserver_api::key::{
     AUX_FILES_KEY, CHECKPOINT_KEY, CONTROLFILE_KEY, DBDIR_KEY, TWOPHASEDIR_KEY,
 };
 use pageserver_api::keyspace::SparseKeySpace;
+use pageserver_api::models::AuxFilePolicy;
 use pageserver_api::reltag::{BlockNumber, RelTag, SlruKind};
 use postgres_ffi::relfile_utils::{FSM_FORKNUM, VISIBILITYMAP_FORKNUM};
 use postgres_ffi::BLCKSZ;
@@ -34,7 +35,7 @@ use std::ops::ControlFlow;
 use std::ops::Range;
 use strum::IntoEnumIterator;
 use tokio_util::sync::CancellationToken;
-use tracing::{debug, trace, warn};
+use tracing::{debug, info, trace, warn};
 use utils::bin_ser::DeserializeError;
 use utils::vec_map::{VecMap, VecMapOrdering};
 use utils::{bin_ser::BeSer, lsn::Lsn};
@@ -279,7 +280,7 @@ impl Timeline {
 
         match RelDirectory::des(&buf).context("deserialization failure") {
             Ok(dir) => {
-                let exists = dir.rels.get(&(tag.relnode, tag.forknum)).is_some();
+                let exists = dir.rels.contains(&(tag.relnode, tag.forknum));
                 Ok(exists)
             }
             Err(e) => Err(PageReconstructError::from(e)),
@@ -379,7 +380,7 @@ impl Timeline {
 
         match SlruSegmentDirectory::des(&buf).context("deserialization failure") {
             Ok(dir) => {
-                let exists = dir.segments.get(&segno).is_some();
+                let exists = dir.segments.contains(&segno);
                 Ok(exists)
             }
             Err(e) => Err(PageReconstructError::from(e)),
@@ -670,7 +671,7 @@ impl Timeline {
         self.get(CHECKPOINT_KEY, lsn, ctx).await
     }
 
-    pub(crate) async fn list_aux_files(
+    async fn list_aux_files_v1(
         &self,
         lsn: Lsn,
         ctx: &RequestContext,
@@ -688,6 +689,68 @@ impl Timeline {
         }
     }
 
+    async fn list_aux_files_v2(
+        &self,
+        lsn: Lsn,
+        ctx: &RequestContext,
+    ) -> Result<HashMap<String, Bytes>, PageReconstructError> {
+        let kv = self
+            .scan(KeySpace::single(Key::metadata_aux_key_range()), lsn, ctx)
+            .await
+            .context("scan")?;
+        let mut result = HashMap::new();
+        let mut sz = 0;
+        for (_, v) in kv {
+            let v = v.context("get value")?;
+            let v = aux_file::decode_file_value_bytes(&v).context("value decode")?;
+            for (fname, content) in v {
+                sz += fname.len();
+                sz += content.len();
+                result.insert(fname, content);
+            }
+        }
+        self.aux_file_size_estimator.on_base_backup(sz);
+        Ok(result)
+    }
+
+    pub(crate) async fn list_aux_files(
+        &self,
+        lsn: Lsn,
+        ctx: &RequestContext,
+    ) -> Result<HashMap<String, Bytes>, PageReconstructError> {
+        let current_policy = self.last_aux_file_policy.load();
+        match current_policy {
+            Some(AuxFilePolicy::V1) | None => self.list_aux_files_v1(lsn, ctx).await,
+            Some(AuxFilePolicy::V2) => self.list_aux_files_v2(lsn, ctx).await,
+            Some(AuxFilePolicy::CrossValidation) => {
+                let v1_result = self.list_aux_files_v1(lsn, ctx).await;
+                let v2_result = self.list_aux_files_v2(lsn, ctx).await;
+                match (v1_result, v2_result) {
+                    (Ok(v1), Ok(v2)) => {
+                        if v1 != v2 {
+                            tracing::error!(
+                                "unmatched aux file v1 v2 result:\nv1 {v1:?}\nv2 {v2:?}"
+                            );
+                            return Err(PageReconstructError::Other(anyhow::anyhow!(
+                                "unmatched aux file v1 v2 result"
+                            )));
+                        }
+                        Ok(v1)
+                    }
+                    (Ok(_), Err(v2)) => {
+                        tracing::error!("aux file v1 returns Ok while aux file v2 returns an err");
+                        Err(v2)
+                    }
+                    (Err(v1), Ok(_)) => {
+                        tracing::error!("aux file v2 returns Ok while aux file v1 returns an err");
+                        Err(v1)
+                    }
+                    (Err(_), Err(v2)) => Err(v2),
+                }
+            }
+        }
+    }
+
     /// Does the same as get_current_logical_size but counted on demand.
     /// Used to initialize the logical size tracking on startup.
     ///
@@ -1143,21 +1206,22 @@ impl<'a> DatadirModification<'a> {
         let mut dbdir = DbDirectory::des(&self.get(DBDIR_KEY, ctx).await.context("read db")?)
             .context("deserialize db")?;
         let rel_dir_key = rel_dir_to_key(rel.spcnode, rel.dbnode);
-        let mut rel_dir = if dbdir.dbdirs.get(&(rel.spcnode, rel.dbnode)).is_none() {
-            // Didn't exist. Update dbdir
-            dbdir.dbdirs.insert((rel.spcnode, rel.dbnode), false);
-            let buf = DbDirectory::ser(&dbdir).context("serialize db")?;
-            self.pending_directory_entries
-                .push((DirectoryKind::Db, dbdir.dbdirs.len()));
-            self.put(DBDIR_KEY, Value::Image(buf.into()));
+        let mut rel_dir =
+            if let hash_map::Entry::Vacant(e) = dbdir.dbdirs.entry((rel.spcnode, rel.dbnode)) {
+                // Didn't exist. Update dbdir
+                e.insert(false);
+                let buf = DbDirectory::ser(&dbdir).context("serialize db")?;
+                self.pending_directory_entries
+                    .push((DirectoryKind::Db, dbdir.dbdirs.len()));
+                self.put(DBDIR_KEY, Value::Image(buf.into()));
 
-            // and create the RelDirectory
-            RelDirectory::default()
-        } else {
-            // reldir already exists, fetch it
-            RelDirectory::des(&self.get(rel_dir_key, ctx).await.context("read db")?)
-                .context("deserialize db")?
-        };
+                // and create the RelDirectory
+                RelDirectory::default()
+            } else {
+                // reldir already exists, fetch it
+                RelDirectory::des(&self.get(rel_dir_key, ctx).await.context("read db")?)
+                    .context("deserialize db")?
+            };
 
         // Add the new relation to the rel directory entry, and write it back
         if !rel_dir.rels.insert((rel.relnode, rel.forknum)) {
@@ -1388,6 +1452,9 @@ impl<'a> DatadirModification<'a> {
     }
 
     pub fn init_aux_dir(&mut self) -> anyhow::Result<()> {
+        if let AuxFilePolicy::V2 = self.tline.get_switch_aux_file_policy() {
+            return Ok(());
+        }
         let buf = AuxFilesDirectory::ser(&AuxFilesDirectory {
             files: HashMap::new(),
         })?;
@@ -1403,89 +1470,163 @@ impl<'a> DatadirModification<'a> {
         content: &[u8],
         ctx: &RequestContext,
     ) -> anyhow::Result<()> {
-        let file_path = path.to_string();
-        let content = if content.is_empty() {
-            None
-        } else {
-            Some(Bytes::copy_from_slice(content))
+        let switch_policy = self.tline.get_switch_aux_file_policy();
+
+        let policy = {
+            let current_policy = self.tline.last_aux_file_policy.load();
+            // Allowed switch path:
+            // * no aux files -> v1/v2/cross-validation
+            // * cross-validation->v2
+            if AuxFilePolicy::is_valid_migration_path(current_policy, switch_policy) {
+                self.tline.last_aux_file_policy.store(Some(switch_policy));
+                self.tline
+                    .remote_client
+                    .schedule_index_upload_for_aux_file_policy_update(Some(switch_policy))?;
+                info!(current=?current_policy, next=?switch_policy, "switching aux file policy");
+                switch_policy
+            } else {
+                // This branch handles non-valid migration path, and the case that switch_policy == current_policy.
+                // And actually, because the migration path always allow unspecified -> *, this unwrap_or will never be hit.
+                current_policy.unwrap_or(AuxFilePolicy::default_tenant_config())
+            }
         };
 
-        let n_files;
-        let mut aux_files = self.tline.aux_files.lock().await;
-        if let Some(mut dir) = aux_files.dir.take() {
-            // We already updated aux files in `self`: emit a delta and update our latest value.
-            dir.upsert(file_path.clone(), content.clone());
-            n_files = dir.files.len();
-            if aux_files.n_deltas == MAX_AUX_FILE_DELTAS {
-                self.put(
-                    AUX_FILES_KEY,
-                    Value::Image(Bytes::from(
-                        AuxFilesDirectory::ser(&dir).context("serialize")?,
-                    )),
-                );
-                aux_files.n_deltas = 0;
+        if let AuxFilePolicy::V2 | AuxFilePolicy::CrossValidation = policy {
+            let key = aux_file::encode_aux_file_key(path);
+            // retrieve the key from the engine
+            let old_val = match self.get(key, ctx).await {
+                Ok(val) => Some(val),
+                Err(PageReconstructError::MissingKey(_)) => None,
+                Err(e) => return Err(e.into()),
+            };
+            let files: Vec<(&str, &[u8])> = if let Some(ref old_val) = old_val {
+                aux_file::decode_file_value(old_val)?
             } else {
-                self.put(
-                    AUX_FILES_KEY,
-                    Value::WalRecord(NeonWalRecord::AuxFile { file_path, content }),
-                );
-                aux_files.n_deltas += 1;
-            }
-            aux_files.dir = Some(dir);
-        } else {
-            // Check if the AUX_FILES_KEY is initialized
-            match self.get(AUX_FILES_KEY, ctx).await {
-                Ok(dir_bytes) => {
-                    let mut dir = AuxFilesDirectory::des(&dir_bytes)?;
-                    // Key is already set, we may append a delta
-                    self.put(
-                        AUX_FILES_KEY,
-                        Value::WalRecord(NeonWalRecord::AuxFile {
-                            file_path: file_path.clone(),
-                            content: content.clone(),
-                        }),
+                Vec::new()
+            };
+            let mut other_files = Vec::with_capacity(files.len());
+            let mut modifying_file = None;
+            for file @ (p, content) in files {
+                if path == p {
+                    assert!(
+                        modifying_file.is_none(),
+                        "duplicated entries found for {}",
+                        path
                     );
-                    dir.upsert(file_path, content);
-                    n_files = dir.files.len();
-                    aux_files.dir = Some(dir);
+                    modifying_file = Some(content);
+                } else {
+                    other_files.push(file);
                 }
-                Err(
-                    e @ (PageReconstructError::AncestorStopping(_)
-                    | PageReconstructError::Cancelled
-                    | PageReconstructError::AncestorLsnTimeout(_)),
-                ) => {
-                    // Important that we do not interpret a shutdown error as "not found" and thereby
-                    // reset the map.
-                    return Err(e.into());
+            }
+            let mut new_files = other_files;
+            match (modifying_file, content.is_empty()) {
+                (Some(old_content), false) => {
+                    self.tline
+                        .aux_file_size_estimator
+                        .on_update(old_content.len(), content.len());
+                    new_files.push((path, content));
                 }
-                // Note: we added missing key error variant in https://github.com/neondatabase/neon/pull/7393 but
-                // the original code assumes all other errors are missing keys. Therefore, we keep the code path
-                // the same for now, though in theory, we should only match the `MissingKey` variant.
-                Err(
-                    PageReconstructError::Other(_)
-                    | PageReconstructError::WalRedo(_)
-                    | PageReconstructError::MissingKey { .. },
-                ) => {
-                    // Key is missing, we must insert an image as the basis for subsequent deltas.
+                (Some(old_content), true) => {
+                    self.tline
+                        .aux_file_size_estimator
+                        .on_remove(old_content.len());
+                    // not adding the file key to the final `new_files` vec.
+                }
+                (None, false) => {
+                    self.tline.aux_file_size_estimator.on_add(content.len());
+                    new_files.push((path, content));
+                }
+                (None, true) => anyhow::bail!("removing non-existing aux file: {}", path),
+            }
+            let new_val = aux_file::encode_file_value(&new_files)?;
+            self.put(key, Value::Image(new_val.into()));
+        }
 
-                    let mut dir = AuxFilesDirectory {
-                        files: HashMap::new(),
-                    };
-                    dir.upsert(file_path, content);
+        if let AuxFilePolicy::V1 | AuxFilePolicy::CrossValidation = policy {
+            let file_path = path.to_string();
+            let content = if content.is_empty() {
+                None
+            } else {
+                Some(Bytes::copy_from_slice(content))
+            };
+
+            let n_files;
+            let mut aux_files = self.tline.aux_files.lock().await;
+            if let Some(mut dir) = aux_files.dir.take() {
+                // We already updated aux files in `self`: emit a delta and update our latest value.
+                dir.upsert(file_path.clone(), content.clone());
+                n_files = dir.files.len();
+                if aux_files.n_deltas == MAX_AUX_FILE_DELTAS {
                     self.put(
                         AUX_FILES_KEY,
                         Value::Image(Bytes::from(
                             AuxFilesDirectory::ser(&dir).context("serialize")?,
                         )),
                     );
-                    n_files = 1;
-                    aux_files.dir = Some(dir);
+                    aux_files.n_deltas = 0;
+                } else {
+                    self.put(
+                        AUX_FILES_KEY,
+                        Value::WalRecord(NeonWalRecord::AuxFile { file_path, content }),
+                    );
+                    aux_files.n_deltas += 1;
+                }
+                aux_files.dir = Some(dir);
+            } else {
+                // Check if the AUX_FILES_KEY is initialized
+                match self.get(AUX_FILES_KEY, ctx).await {
+                    Ok(dir_bytes) => {
+                        let mut dir = AuxFilesDirectory::des(&dir_bytes)?;
+                        // Key is already set, we may append a delta
+                        self.put(
+                            AUX_FILES_KEY,
+                            Value::WalRecord(NeonWalRecord::AuxFile {
+                                file_path: file_path.clone(),
+                                content: content.clone(),
+                            }),
+                        );
+                        dir.upsert(file_path, content);
+                        n_files = dir.files.len();
+                        aux_files.dir = Some(dir);
+                    }
+                    Err(
+                        e @ (PageReconstructError::AncestorStopping(_)
+                        | PageReconstructError::Cancelled
+                        | PageReconstructError::AncestorLsnTimeout(_)),
+                    ) => {
+                        // Important that we do not interpret a shutdown error as "not found" and thereby
+                        // reset the map.
+                        return Err(e.into());
+                    }
+                    // Note: we added missing key error variant in https://github.com/neondatabase/neon/pull/7393 but
+                    // the original code assumes all other errors are missing keys. Therefore, we keep the code path
+                    // the same for now, though in theory, we should only match the `MissingKey` variant.
+                    Err(
+                        PageReconstructError::Other(_)
+                        | PageReconstructError::WalRedo(_)
+                        | PageReconstructError::MissingKey { .. },
+                    ) => {
+                        // Key is missing, we must insert an image as the basis for subsequent deltas.
+
+                        let mut dir = AuxFilesDirectory {
+                            files: HashMap::new(),
+                        };
+                        dir.upsert(file_path, content);
+                        self.put(
+                            AUX_FILES_KEY,
+                            Value::Image(Bytes::from(
+                                AuxFilesDirectory::ser(&dir).context("serialize")?,
+                            )),
+                        );
+                        n_files = 1;
+                        aux_files.dir = Some(dir);
+                    }
                 }
             }
-        }
 
-        self.pending_directory_entries
-            .push((DirectoryKind::AuxFiles, n_files));
+            self.pending_directory_entries
+                .push((DirectoryKind::AuxFiles, n_files));
+        }
 
         Ok(())
     }
@@ -1577,7 +1718,7 @@ impl<'a> DatadirModification<'a> {
         }
 
         if !self.pending_deletions.is_empty() {
-            writer.delete_batch(&self.pending_deletions).await?;
+            writer.delete_batch(&self.pending_deletions, ctx).await?;
             self.pending_deletions.clear();
         }
 

pageserver/src/repository.rs

@@ -33,7 +33,6 @@ impl Value {
     }
 }
 
-#[cfg(test)]
 #[derive(Debug, PartialEq)]
 pub(crate) enum InvalidInput {
     TooShortValue,
@@ -42,10 +41,8 @@ pub(crate) enum InvalidInput {
 
 /// We could have a ValueRef where everything is `serde(borrow)`. Before implementing that, lets
 /// use this type for querying if a slice looks some particular way.
-#[cfg(test)]
 pub(crate) struct ValueBytes;
 
-#[cfg(test)]
 impl ValueBytes {
     pub(crate) fn will_init(raw: &[u8]) -> Result<bool, InvalidInput> {
         if raw.len() < 12 {

pageserver/src/task_mgr.rs

@@ -319,6 +319,9 @@ pub enum TaskKind {
     // Eviction. One per timeline.
     Eviction,
 
+    // Ingest housekeeping (flushing ephemeral layers on time threshold or disk pressure)
+    IngestHousekeeping,
+
     /// See [`crate::disk_usage_eviction_task`].
     DiskUsageEviction,
 
@@ -363,8 +366,12 @@ pub enum TaskKind {
 
     EphemeralFilePreWarmPageCache,
 
+    LayerDownload,
+
     #[cfg(test)]
     UnitTest,
+
+    DetachAncestor,
 }
 
 #[derive(Default)]

pageserver/src/tenant/blob_io.rs

@@ -130,8 +130,9 @@ impl<const BUFFERED: bool> BlobWriter<BUFFERED> {
     async fn write_all_unbuffered<B: BoundedBuf<Buf = Buf>, Buf: IoBuf + Send>(
         &mut self,
         src_buf: B,
+        ctx: &RequestContext,
     ) -> (B::Buf, Result<(), Error>) {
-        let (src_buf, res) = self.inner.write_all(src_buf).await;
+        let (src_buf, res) = self.inner.write_all(src_buf, ctx).await;
         let nbytes = match res {
             Ok(nbytes) => nbytes,
             Err(e) => return (src_buf, Err(e)),
@@ -142,9 +143,9 @@ impl<const BUFFERED: bool> BlobWriter<BUFFERED> {
 
     #[inline(always)]
     /// Flushes the internal buffer to the underlying `VirtualFile`.
-    pub async fn flush_buffer(&mut self) -> Result<(), Error> {
+    pub async fn flush_buffer(&mut self, ctx: &RequestContext) -> Result<(), Error> {
         let buf = std::mem::take(&mut self.buf);
-        let (mut buf, res) = self.inner.write_all(buf).await;
+        let (mut buf, res) = self.inner.write_all(buf, ctx).await;
         res?;
         buf.clear();
         self.buf = buf;
@@ -165,10 +166,11 @@ impl<const BUFFERED: bool> BlobWriter<BUFFERED> {
     async fn write_all<B: BoundedBuf<Buf = Buf>, Buf: IoBuf + Send>(
         &mut self,
         src_buf: B,
+        ctx: &RequestContext,
     ) -> (B::Buf, Result<(), Error>) {
         if !BUFFERED {
             assert!(self.buf.is_empty());
-            return self.write_all_unbuffered(src_buf).await;
+            return self.write_all_unbuffered(src_buf, ctx).await;
         }
         let remaining = Self::CAPACITY - self.buf.len();
         let src_buf_len = src_buf.bytes_init();
@@ -183,7 +185,7 @@ impl<const BUFFERED: bool> BlobWriter<BUFFERED> {
         }
         // Then, if the buffer is full, flush it out
         if self.buf.len() == Self::CAPACITY {
-            if let Err(e) = self.flush_buffer().await {
+            if let Err(e) = self.flush_buffer(ctx).await {
                 return (Slice::into_inner(src_buf), Err(e));
             }
         }
@@ -199,7 +201,7 @@ impl<const BUFFERED: bool> BlobWriter<BUFFERED> {
                 assert_eq!(copied, src_buf.len());
                 Slice::into_inner(src_buf)
             } else {
-                let (src_buf, res) = self.write_all_unbuffered(src_buf).await;
+                let (src_buf, res) = self.write_all_unbuffered(src_buf, ctx).await;
                 if let Err(e) = res {
                     return (src_buf, Err(e));
                 }
@@ -216,6 +218,7 @@ impl<const BUFFERED: bool> BlobWriter<BUFFERED> {
     pub async fn write_blob<B: BoundedBuf<Buf = Buf>, Buf: IoBuf + Send>(
         &mut self,
         srcbuf: B,
+        ctx: &RequestContext,
     ) -> (B::Buf, Result<u64, Error>) {
         let offset = self.offset;
 
@@ -227,7 +230,7 @@ impl<const BUFFERED: bool> BlobWriter<BUFFERED> {
             if len < 128 {
                 // Short blob. Write a 1-byte length header
                 io_buf.put_u8(len as u8);
-                self.write_all(io_buf).await
+                self.write_all(io_buf, ctx).await
             } else {
                 // Write a 4-byte length header
                 if len > 0x7fff_ffff {
@@ -242,7 +245,7 @@ impl<const BUFFERED: bool> BlobWriter<BUFFERED> {
                 let mut len_buf = (len as u32).to_be_bytes();
                 len_buf[0] |= 0x80;
                 io_buf.extend_from_slice(&len_buf[..]);
-                self.write_all(io_buf).await
+                self.write_all(io_buf, ctx).await
             }
         }
         .await;
@@ -251,7 +254,7 @@ impl<const BUFFERED: bool> BlobWriter<BUFFERED> {
             Ok(_) => (),
             Err(e) => return (Slice::into_inner(srcbuf.slice(..)), Err(e)),
         }
-        let (srcbuf, res) = self.write_all(srcbuf).await;
+        let (srcbuf, res) = self.write_all(srcbuf, ctx).await;
         (srcbuf, res.map(|_| offset))
     }
 }
@@ -261,8 +264,8 @@ impl BlobWriter<true> {
     ///
     /// This function flushes the internal buffer before giving access
     /// to the underlying `VirtualFile`.
-    pub async fn into_inner(mut self) -> Result<VirtualFile, Error> {
-        self.flush_buffer().await?;
+    pub async fn into_inner(mut self, ctx: &RequestContext) -> Result<VirtualFile, Error> {
+        self.flush_buffer(ctx).await?;
         Ok(self.inner)
     }
 
@@ -296,22 +299,22 @@ mod tests {
         // Write part (in block to drop the file)
         let mut offsets = Vec::new();
         {
-            let file = VirtualFile::create(pathbuf.as_path()).await?;
+            let file = VirtualFile::create(pathbuf.as_path(), &ctx).await?;
             let mut wtr = BlobWriter::<BUFFERED>::new(file, 0);
             for blob in blobs.iter() {
-                let (_, res) = wtr.write_blob(blob.clone()).await;
+                let (_, res) = wtr.write_blob(blob.clone(), &ctx).await;
                 let offs = res?;
                 offsets.push(offs);
             }
             // Write out one page worth of zeros so that we can
             // read again with read_blk
-            let (_, res) = wtr.write_blob(vec![0; PAGE_SZ]).await;
+            let (_, res) = wtr.write_blob(vec![0; PAGE_SZ], &ctx).await;
             let offs = res?;
             println!("Writing final blob at offs={offs}");
-            wtr.flush_buffer().await?;
+            wtr.flush_buffer(&ctx).await?;
         }
 
-        let file = VirtualFile::open(pathbuf.as_path()).await?;
+        let file = VirtualFile::open(pathbuf.as_path(), &ctx).await?;
         let rdr = BlockReaderRef::VirtualFile(&file);
         let rdr = BlockCursor::new(rdr);
         for (idx, (blob, offset)) in blobs.iter().zip(offsets.iter()).enumerate() {

pageserver/src/tenant/block_io.rs

@@ -102,7 +102,7 @@ impl<'a> BlockReaderRef<'a> {
             #[cfg(test)]
             TestDisk(r) => r.read_blk(blknum),
             #[cfg(test)]
-            VirtualFile(r) => r.read_blk(blknum).await,
+            VirtualFile(r) => r.read_blk(blknum, ctx).await,
         }
     }
 }
@@ -177,10 +177,11 @@ impl<'a> FileBlockReader<'a> {
         &self,
         buf: PageWriteGuard<'static>,
         blkno: u32,
+        ctx: &RequestContext,
     ) -> Result<PageWriteGuard<'static>, std::io::Error> {
         assert!(buf.len() == PAGE_SZ);
         self.file
-            .read_exact_at_page(buf, blkno as u64 * PAGE_SZ as u64)
+            .read_exact_at_page(buf, blkno as u64 * PAGE_SZ as u64, ctx)
             .await
     }
     /// Read a block.
@@ -206,7 +207,7 @@ impl<'a> FileBlockReader<'a> {
             ReadBufResult::Found(guard) => Ok(guard.into()),
             ReadBufResult::NotFound(write_guard) => {
                 // Read the page from disk into the buffer
-                let write_guard = self.fill_buffer(write_guard, blknum).await?;
+                let write_guard = self.fill_buffer(write_guard, blknum, ctx).await?;
                 Ok(write_guard.mark_valid().into())
             }
         }

pageserver/src/tenant/config.rs

@@ -9,6 +9,7 @@
 //! may lead to a data loss.
 //!
 use anyhow::bail;
+use pageserver_api::models::AuxFilePolicy;
 use pageserver_api::models::CompactionAlgorithm;
 use pageserver_api::models::EvictionPolicy;
 use pageserver_api::models::{self, ThrottleConfig};
@@ -370,9 +371,11 @@ pub struct TenantConf {
     // Expresed in multiples of checkpoint distance.
     pub image_layer_creation_check_threshold: u8,
 
-    /// Switch to aux file v2. Switching this flag requires the user has not written any aux file into
+    /// Switch to a new aux file policy. Switching this flag requires the user has not written any aux file into
     /// the storage before, and this flag cannot be switched back. Otherwise there will be data corruptions.
-    pub switch_to_aux_file_v2: bool,
+    /// There is a `last_aux_file_policy` flag which gets persisted in `index_part.json` once the first aux
+    /// file is written.
+    pub switch_aux_file_policy: AuxFilePolicy,
 }
 
 /// Same as TenantConf, but this struct preserves the information about
@@ -471,7 +474,7 @@ pub struct TenantConfOpt {
 
     #[serde(skip_serializing_if = "Option::is_none")]
     #[serde(default)]
-    pub switch_to_aux_file_v2: Option<bool>,
+    pub switch_aux_file_policy: Option<AuxFilePolicy>,
 }
 
 impl TenantConfOpt {
@@ -529,9 +532,9 @@ impl TenantConfOpt {
             image_layer_creation_check_threshold: self
                 .image_layer_creation_check_threshold
                 .unwrap_or(global_conf.image_layer_creation_check_threshold),
-            switch_to_aux_file_v2: self
-                .switch_to_aux_file_v2
-                .unwrap_or(global_conf.switch_to_aux_file_v2),
+            switch_aux_file_policy: self
+                .switch_aux_file_policy
+                .unwrap_or(global_conf.switch_aux_file_policy),
         }
     }
 }
@@ -573,7 +576,7 @@ impl Default for TenantConf {
             lazy_slru_download: false,
             timeline_get_throttle: crate::tenant::throttle::Config::disabled(),
             image_layer_creation_check_threshold: DEFAULT_IMAGE_LAYER_CREATION_CHECK_THRESHOLD,
-            switch_to_aux_file_v2: false,
+            switch_aux_file_policy: AuxFilePolicy::default_tenant_config(),
         }
     }
 }
@@ -648,7 +651,7 @@ impl From<TenantConfOpt> for models::TenantConfig {
             lazy_slru_download: value.lazy_slru_download,
             timeline_get_throttle: value.timeline_get_throttle.map(ThrottleConfig::from),
             image_layer_creation_check_threshold: value.image_layer_creation_check_threshold,
-            switch_to_aux_file_v2: value.switch_to_aux_file_v2,
+            switch_aux_file_policy: value.switch_aux_file_policy,
         }
     }
 }

pageserver/src/tenant/delete.rs

@@ -181,25 +181,23 @@ async fn ensure_timelines_dir_empty(timelines_path: &Utf8Path) -> Result<(), Del
 
 async fn remove_tenant_remote_delete_mark(
     conf: &PageServerConf,
-    remote_storage: Option<&GenericRemoteStorage>,
+    remote_storage: &GenericRemoteStorage,
     tenant_shard_id: &TenantShardId,
     cancel: &CancellationToken,
 ) -> Result<(), DeleteTenantError> {
-    if let Some(remote_storage) = remote_storage {
-        let path = remote_tenant_delete_mark_path(conf, tenant_shard_id)?;
-        backoff::retry(
-            || async { remote_storage.delete(&path, cancel).await },
-            TimeoutOrCancel::caused_by_cancel,
-            FAILED_UPLOAD_WARN_THRESHOLD,
-            FAILED_REMOTE_OP_RETRIES,
-            "remove_tenant_remote_delete_mark",
-            cancel,
-        )
-        .await
-        .ok_or_else(|| anyhow::Error::new(TimeoutOrCancel::Cancel))
-        .and_then(|x| x)
-        .context("remove_tenant_remote_delete_mark")?;
-    }
+    let path = remote_tenant_delete_mark_path(conf, tenant_shard_id)?;
+    backoff::retry(
+        || async { remote_storage.delete(&path, cancel).await },
+        TimeoutOrCancel::caused_by_cancel,
+        FAILED_UPLOAD_WARN_THRESHOLD,
+        FAILED_REMOTE_OP_RETRIES,
+        "remove_tenant_remote_delete_mark",
+        cancel,
+    )
+    .await
+    .ok_or_else(|| anyhow::Error::new(TimeoutOrCancel::Cancel))
+    .and_then(|x| x)
+    .context("remove_tenant_remote_delete_mark")?;
     Ok(())
 }
 
@@ -297,7 +295,7 @@ impl DeleteTenantFlow {
     #[instrument(skip_all)]
     pub(crate) async fn run(
         conf: &'static PageServerConf,
-        remote_storage: Option<GenericRemoteStorage>,
+        remote_storage: GenericRemoteStorage,
         tenants: &'static std::sync::RwLock<TenantsMap>,
         tenant: Arc<Tenant>,
         cancel: &CancellationToken,
@@ -308,9 +306,7 @@ impl DeleteTenantFlow {
 
         let mut guard = Self::prepare(&tenant).await?;
 
-        if let Err(e) =
-            Self::run_inner(&mut guard, conf, remote_storage.as_ref(), &tenant, cancel).await
-        {
+        if let Err(e) = Self::run_inner(&mut guard, conf, &remote_storage, &tenant, cancel).await {
             tenant.set_broken(format!("{e:#}")).await;
             return Err(e);
         }
@@ -327,7 +323,7 @@ impl DeleteTenantFlow {
     async fn run_inner(
         guard: &mut OwnedMutexGuard<Self>,
         conf: &'static PageServerConf,
-        remote_storage: Option<&GenericRemoteStorage>,
+        remote_storage: &GenericRemoteStorage,
         tenant: &Tenant,
         cancel: &CancellationToken,
     ) -> Result<(), DeleteTenantError> {
@@ -339,14 +335,9 @@ impl DeleteTenantFlow {
             ))?
         });
 
-        // IDEA: implement detach as delete without remote storage. Then they would use the same lock (deletion_progress) so wont contend.
-        // Though sounds scary, different mark name?
-        // Detach currently uses remove_dir_all so in case of a crash we can end up in a weird state.
-        if let Some(remote_storage) = &remote_storage {
-            create_remote_delete_mark(conf, remote_storage, &tenant.tenant_shard_id, cancel)
-                .await
-                .context("remote_mark")?
-        }
+        create_remote_delete_mark(conf, remote_storage, &tenant.tenant_shard_id, cancel)
+            .await
+            .context("remote_mark")?;
 
         fail::fail_point!("tenant-delete-before-create-local-mark", |_| {
             Err(anyhow::anyhow!(
@@ -483,7 +474,7 @@ impl DeleteTenantFlow {
     fn schedule_background(
         guard: OwnedMutexGuard<Self>,
         conf: &'static PageServerConf,
-        remote_storage: Option<GenericRemoteStorage>,
+        remote_storage: GenericRemoteStorage,
         tenants: &'static std::sync::RwLock<TenantsMap>,
         tenant: Arc<Tenant>,
     ) {
@@ -512,7 +503,7 @@ impl DeleteTenantFlow {
     async fn background(
         mut guard: OwnedMutexGuard<Self>,
         conf: &PageServerConf,
-        remote_storage: Option<GenericRemoteStorage>,
+        remote_storage: GenericRemoteStorage,
         tenants: &'static std::sync::RwLock<TenantsMap>,
         tenant: &Arc<Tenant>,
     ) -> Result<(), DeleteTenantError> {
@@ -551,7 +542,7 @@ impl DeleteTenantFlow {
 
         remove_tenant_remote_delete_mark(
             conf,
-            remote_storage.as_ref(),
+            &remote_storage,
             &tenant.tenant_shard_id,
             &task_mgr::shutdown_token(),
         )
@@ -585,9 +576,20 @@ impl DeleteTenantFlow {
 
                     // FIXME: we should not be modifying this from outside of mgr.rs.
                     // This will go away when we simplify deletion (https://github.com/neondatabase/neon/issues/5080)
-                    crate::metrics::TENANT_MANAGER
-                        .tenant_slots
-                        .set(locked.len() as u64);
+
+                    // Update stats
+                    match &removed {
+                        TenantsMapRemoveResult::Occupied(slot) => {
+                            crate::metrics::TENANT_MANAGER.slot_removed(slot);
+                        }
+                        TenantsMapRemoveResult::InProgress(barrier) => {
+                            crate::metrics::TENANT_MANAGER
+                                .slot_removed(&TenantSlot::InProgress(barrier.clone()));
+                        }
+                        TenantsMapRemoveResult::Vacant => {
+                            // Nothing changed in map, no metric update
+                        }
+                    }
 
                     match removed {
                         TenantsMapRemoveResult::Occupied(TenantSlot::Attached(tenant)) => {

pageserver/src/tenant/ephemeral_file.rs

@@ -28,6 +28,7 @@ impl EphemeralFile {
         conf: &PageServerConf,
         tenant_shard_id: TenantShardId,
         timeline_id: TimelineId,
+        ctx: &RequestContext,
     ) -> Result<EphemeralFile, io::Error> {
         static NEXT_FILENAME: AtomicU64 = AtomicU64::new(1);
         let filename_disambiguator =
@@ -45,6 +46,7 @@ impl EphemeralFile {
                 .read(true)
                 .write(true)
                 .create(true),
+            ctx,
         )
         .await?;
 
@@ -74,7 +76,7 @@ impl EphemeralFile {
     pub(crate) async fn write_blob(
         &mut self,
         srcbuf: &[u8],
-        _ctx: &RequestContext,
+        ctx: &RequestContext,
     ) -> Result<u64, io::Error> {
         let pos = self.rw.bytes_written();
 
@@ -83,15 +85,15 @@ impl EphemeralFile {
             // short one-byte length header
             let len_buf = [srcbuf.len() as u8];
 
-            self.rw.write_all_borrowed(&len_buf).await?;
+            self.rw.write_all_borrowed(&len_buf, ctx).await?;
         } else {
             let mut len_buf = u32::to_be_bytes(srcbuf.len() as u32);
             len_buf[0] |= 0x80;
-            self.rw.write_all_borrowed(&len_buf).await?;
+            self.rw.write_all_borrowed(&len_buf, ctx).await?;
         }
 
         // Write the payload
-        self.rw.write_all_borrowed(srcbuf).await?;
+        self.rw.write_all_borrowed(srcbuf, ctx).await?;
 
         Ok(pos)
     }
@@ -153,7 +155,7 @@ mod tests {
     async fn test_ephemeral_blobs() -> Result<(), io::Error> {
         let (conf, tenant_id, timeline_id, ctx) = harness("ephemeral_blobs")?;
 
-        let mut file = EphemeralFile::create(conf, tenant_id, timeline_id).await?;
+        let mut file = EphemeralFile::create(conf, tenant_id, timeline_id, &ctx).await?;
 
         let pos_foo = file.write_blob(b"foo", &ctx).await?;
         assert_eq!(

pageserver/src/tenant/ephemeral_file/page_caching.rs

@@ -35,10 +35,14 @@ impl RW {
         self.page_cache_file_id
     }
 
-    pub(crate) async fn write_all_borrowed(&mut self, srcbuf: &[u8]) -> Result<usize, io::Error> {
+    pub(crate) async fn write_all_borrowed(
+        &mut self,
+        srcbuf: &[u8],
+        ctx: &RequestContext,
+    ) -> Result<usize, io::Error> {
         // It doesn't make sense to proactively fill the page cache on the Pageserver write path
         // because Compute is unlikely to access recently written data.
-        self.rw.write_all_borrowed(srcbuf).await
+        self.rw.write_all_borrowed(srcbuf, ctx).await
     }
 
     pub(crate) fn bytes_written(&self) -> u64 {
@@ -74,7 +78,7 @@ impl RW {
                     page_cache::ReadBufResult::NotFound(write_guard) => {
                         let write_guard = writer
                             .file
-                            .read_exact_at_page(write_guard, blknum as u64 * PAGE_SZ as u64)
+                            .read_exact_at_page(write_guard, blknum as u64 * PAGE_SZ as u64, ctx)
                             .await?;
                         let read_guard = write_guard.mark_valid();
                         return Ok(BlockLease::PageReadGuard(read_guard));
@@ -134,6 +138,7 @@ impl crate::virtual_file::owned_buffers_io::write::OwnedAsyncWriter for PreWarmi
     >(
         &mut self,
         buf: B,
+        ctx: &RequestContext,
     ) -> std::io::Result<(usize, B::Buf)> {
         let buf = buf.slice(..);
         let saved_bounds = buf.bounds(); // save for reconstructing the Slice from iobuf after the IO is done
@@ -150,7 +155,7 @@ impl crate::virtual_file::owned_buffers_io::write::OwnedAsyncWriter for PreWarmi
         );
 
         // Do the IO.
-        let iobuf = match self.file.write_all(buf).await {
+        let iobuf = match self.file.write_all(buf, ctx).await {
             (iobuf, Ok(nwritten)) => {
                 assert_eq!(nwritten, buflen);
                 iobuf

pageserver/src/tenant/ephemeral_file/zero_padded_read_write.rs

@@ -20,6 +20,7 @@
 mod zero_padded;
 
 use crate::{
+    context::RequestContext,
     page_cache::PAGE_SZ,
     virtual_file::owned_buffers_io::{
         self,
@@ -60,8 +61,12 @@ where
         self.buffered_writer.as_inner().as_inner()
     }
 
-    pub async fn write_all_borrowed(&mut self, buf: &[u8]) -> std::io::Result<usize> {
-        self.buffered_writer.write_buffered_borrowed(buf).await
+    pub async fn write_all_borrowed(
+        &mut self,
+        buf: &[u8],
+        ctx: &RequestContext,
+    ) -> std::io::Result<usize> {
+        self.buffered_writer.write_buffered_borrowed(buf, ctx).await
     }
 
     pub fn bytes_written(&self) -> u64 {

pageserver/src/tenant/layer_map.rs

@@ -588,7 +588,7 @@ impl LayerMap {
             let kr = Key::from_i128(current_key)..Key::from_i128(change_key);
             coverage.push((kr, current_val.take()));
             current_key = change_key;
-            current_val = change_val.clone();
+            current_val.clone_from(&change_val);
         }
 
         // Add the final interval
@@ -672,12 +672,12 @@ impl LayerMap {
         // Loop through the delta coverage and recurse on each part
         for (change_key, change_val) in version.delta_coverage.range(start..end) {
             // If there's a relevant delta in this part, add 1 and recurse down
-            if let Some(val) = current_val {
+            if let Some(val) = &current_val {
                 if val.get_lsn_range().end > lsn.start {
                     let kr = Key::from_i128(current_key)..Key::from_i128(change_key);
                     let lr = lsn.start..val.get_lsn_range().start;
                     if !kr.is_empty() {
-                        let base_count = Self::is_reimage_worthy(&val, key) as usize;
+                        let base_count = Self::is_reimage_worthy(val, key) as usize;
                         let new_limit = limit.map(|l| l - base_count);
                         let max_stacked_deltas_underneath = self.count_deltas(&kr, &lr, new_limit);
                         max_stacked_deltas = std::cmp::max(
@@ -689,17 +689,17 @@ impl LayerMap {
             }
 
             current_key = change_key;
-            current_val = change_val.clone();
+            current_val.clone_from(&change_val);
         }
 
         // Consider the last part
-        if let Some(val) = current_val {
+        if let Some(val) = &current_val {
             if val.get_lsn_range().end > lsn.start {
                 let kr = Key::from_i128(current_key)..Key::from_i128(end);
                 let lr = lsn.start..val.get_lsn_range().start;
 
                 if !kr.is_empty() {
-                    let base_count = Self::is_reimage_worthy(&val, key) as usize;
+                    let base_count = Self::is_reimage_worthy(val, key) as usize;
                     let new_limit = limit.map(|l| l - base_count);
                     let max_stacked_deltas_underneath = self.count_deltas(&kr, &lr, new_limit);
                     max_stacked_deltas = std::cmp::max(

pageserver/src/tenant/metadata.rs

@@ -207,6 +207,24 @@ impl TimelineMetadata {
         self.body.ancestor_lsn
     }
 
+    /// When reparenting, the `ancestor_lsn` does not change.
+    pub fn reparent(&mut self, timeline: &TimelineId) {
+        assert!(self.body.ancestor_timeline.is_some());
+        // no assertion for redoing this: it's fine, we may have to repeat this multiple times over
+        self.body.ancestor_timeline = Some(*timeline);
+    }
+
+    pub fn detach_from_ancestor(&mut self, branchpoint: &(TimelineId, Lsn)) {
+        if let Some(ancestor) = self.body.ancestor_timeline {
+            assert_eq!(ancestor, branchpoint.0);
+        }
+        if self.body.ancestor_lsn != Lsn(0) {
+            assert_eq!(self.body.ancestor_lsn, branchpoint.1);
+        }
+        self.body.ancestor_timeline = None;
+        self.body.ancestor_lsn = Lsn(0);
+    }
+
     pub fn latest_gc_cutoff_lsn(&self) -> Lsn {
         self.body.latest_gc_cutoff_lsn
     }

pageserver/src/tenant/mgr.rs

@@ -16,10 +16,9 @@ use std::cmp::Ordering;
 use std::collections::{BTreeMap, HashMap};
 use std::ops::Deref;
 use std::sync::Arc;
-use std::time::{Duration, Instant};
+use std::time::Duration;
 use sysinfo::SystemExt;
 use tokio::fs;
-use utils::timeout::{timeout_cancellable, TimeoutCancellableError};
 
 use anyhow::Context;
 use once_cell::sync::Lazy;
@@ -47,7 +46,7 @@ use crate::tenant::span::debug_assert_current_span_has_tenant_id;
 use crate::tenant::storage_layer::inmemory_layer;
 use crate::tenant::timeline::ShutdownMode;
 use crate::tenant::{AttachedTenantConf, SpawnMode, Tenant, TenantState};
-use crate::{InitializationOrder, IGNORED_TENANT_FILE_NAME, METADATA_FILE_NAME, TEMP_FILE_SUFFIX};
+use crate::{InitializationOrder, IGNORED_TENANT_FILE_NAME, TEMP_FILE_SUFFIX};
 
 use utils::crashsafe::path_with_suffix_extension;
 use utils::fs_ext::PathExt;
@@ -56,6 +55,7 @@ use utils::id::{TenantId, TimelineId};
 
 use super::delete::DeleteTenantError;
 use super::secondary::SecondaryTenant;
+use super::timeline::detach_ancestor::PreparedTimelineDetach;
 use super::TenantSharedResources;
 
 /// For a tenant that appears in TenantsMap, it may either be
@@ -118,6 +118,7 @@ pub(crate) enum TenantsMapRemoveResult {
 
 /// When resolving a TenantId to a shard, we may be looking for the 0th
 /// shard, or we might be looking for whichever shard holds a particular page.
+#[derive(Copy, Clone)]
 pub(crate) enum ShardSelector {
     /// Only return the 0th shard, if it is present.  If a non-0th shard is present,
     /// ignore it.
@@ -168,6 +169,14 @@ impl TenantStartupMode {
     }
 }
 
+/// Result type for looking up a TenantId to a specific shard
+pub(crate) enum ShardResolveResult {
+    NotFound,
+    Found(Arc<Tenant>),
+    // Wait for this barrrier, then query again
+    InProgress(utils::completion::Barrier),
+}
+
 impl TenantsMap {
     /// Convenience function for typical usage, where we want to get a `Tenant` object, for
     /// working with attached tenants.  If the TenantId is in the map but in Secondary state,
@@ -181,51 +190,6 @@ impl TenantsMap {
         }
     }
 
-    /// A page service client sends a TenantId, and to look up the correct Tenant we must
-    /// resolve this to a fully qualified TenantShardId.
-    fn resolve_attached_shard(
-        &self,
-        tenant_id: &TenantId,
-        selector: ShardSelector,
-    ) -> Option<TenantShardId> {
-        let mut want_shard = None;
-        match self {
-            TenantsMap::Initializing => None,
-            TenantsMap::Open(m) | TenantsMap::ShuttingDown(m) => {
-                for slot in m.range(TenantShardId::tenant_range(*tenant_id)) {
-                    // Ignore all slots that don't contain an attached tenant
-                    let tenant = match &slot.1 {
-                        TenantSlot::Attached(t) => t,
-                        _ => continue,
-                    };
-
-                    match selector {
-                        ShardSelector::First => return Some(*slot.0),
-                        ShardSelector::Zero if slot.0.shard_number == ShardNumber(0) => {
-                            return Some(*slot.0)
-                        }
-                        ShardSelector::Page(key) => {
-                            // First slot we see for this tenant, calculate the expected shard number
-                            // for the key: we will use this for checking if this and subsequent
-                            // slots contain the key, rather than recalculating the hash each time.
-                            if want_shard.is_none() {
-                                want_shard = Some(tenant.shard_identity.get_shard_number(&key));
-                            }
-
-                            if Some(tenant.shard_identity.number) == want_shard {
-                                return Some(*slot.0);
-                            }
-                        }
-                        _ => continue,
-                    }
-                }
-
-                // Fall through: we didn't find an acceptable shard
-                None
-            }
-        }
-    }
-
     /// Only for use from DeleteTenantFlow.  This method directly removes a TenantSlot from the map.
     ///
     /// The normal way to remove a tenant is using a SlotGuard, which will gracefully remove the guarded
@@ -246,6 +210,7 @@ impl TenantsMap {
         }
     }
 
+    #[cfg(all(debug_assertions, not(test)))]
     pub(crate) fn len(&self) -> usize {
         match self {
             TenantsMap::Initializing => 0,
@@ -389,22 +354,17 @@ async fn init_load_generations(
     // deletion list entries may still be valid.  We provide that by pushing a recovery operation into
     // the queue. Sequential processing of te queue ensures that recovery is done before any new tenant deletions
     // are processed, even though we don't block on recovery completing here.
-    //
-    // Must only do this if remote storage is enabled, otherwise deletion queue
-    // is not running and channel push will fail.
-    if resources.remote_storage.is_some() {
-        let attached_tenants = generations
-            .iter()
-            .flat_map(|(id, start_mode)| {
-                match start_mode {
-                    TenantStartupMode::Attached((_mode, generation)) => Some(generation),
-                    TenantStartupMode::Secondary => None,
-                }
-                .map(|gen| (*id, *gen))
-            })
-            .collect();
-        resources.deletion_queue_client.recover(attached_tenants)?;
-    }
+    let attached_tenants = generations
+        .iter()
+        .flat_map(|(id, start_mode)| {
+            match start_mode {
+                TenantStartupMode::Attached((_mode, generation)) => Some(generation),
+                TenantStartupMode::Secondary => None,
+            }
+            .map(|gen| (*id, *gen))
+        })
+        .collect();
+    resources.deletion_queue_client.recover(attached_tenants)?;
 
     Ok(Some(generations))
 }
@@ -458,53 +418,6 @@ fn load_tenant_config(
         }
     };
 
-    // Clean up legacy `metadata` files.
-    // Doing it here because every single tenant directory is visited here.
-    // In any later code, there's different treatment of tenant dirs
-    // ... depending on whether the tenant is in re-attach response or not
-    // ... epending on whether the tenant is ignored or not
-    assert_eq!(
-        &conf.tenant_path(&tenant_shard_id),
-        &tenant_dir_path,
-        "later use of conf....path() methods would be dubious"
-    );
-    let timelines: Vec<TimelineId> = match conf.timelines_path(&tenant_shard_id).read_dir_utf8() {
-        Ok(iter) => {
-            let mut timelines = Vec::new();
-            for res in iter {
-                let p = res?;
-                let Some(timeline_id) = p.file_name().parse::<TimelineId>().ok() else {
-                    // skip any entries that aren't TimelineId, such as
-                    // - *.___temp dirs
-                    // - unfinished initdb uploads (test_non_uploaded_root_timeline_is_deleted_after_restart)
-                    continue;
-                };
-                timelines.push(timeline_id);
-            }
-            timelines
-        }
-        Err(e) if e.kind() == std::io::ErrorKind::NotFound => vec![],
-        Err(e) => return Err(anyhow::anyhow!(e)),
-    };
-    for timeline_id in timelines {
-        let timeline_path = &conf.timeline_path(&tenant_shard_id, &timeline_id);
-        let metadata_path = timeline_path.join(METADATA_FILE_NAME);
-        match std::fs::remove_file(&metadata_path) {
-            Ok(()) => {
-                crashsafe::fsync(timeline_path)
-                    .context("fsync timeline dir after removing legacy metadata file")?;
-                info!("removed legacy metadata file at {metadata_path}");
-            }
-            Err(e) if e.kind() == std::io::ErrorKind::NotFound => {
-                // something removed the file earlier, or it was never there
-                // We don't care, this software version doesn't write it again, so, we're good.
-            }
-            Err(e) => {
-                anyhow::bail!("remove legacy metadata file: {e}: {metadata_path}");
-            }
-        }
-    }
-
     let tenant_ignore_mark_file = tenant_dir_path.join(IGNORED_TENANT_FILE_NAME);
     if tenant_ignore_mark_file.exists() {
         info!("Found an ignore mark file {tenant_ignore_mark_file:?}, skipping the tenant");
@@ -609,6 +522,7 @@ pub async fn init_tenant_mgr(
                     TenantSlot::Attached(Tenant::create_broken_tenant(
                         conf,
                         tenant_shard_id,
+                        resources.remote_storage.clone(),
                         format!("{}", e),
                     )),
                 );
@@ -746,6 +660,7 @@ pub async fn init_tenant_mgr(
             }
         };
 
+        METRICS.slot_inserted(&slot);
         tenants.insert(tenant_shard_id, slot);
     }
 
@@ -753,7 +668,7 @@ pub async fn init_tenant_mgr(
 
     let mut tenants_map = TENANTS.write().unwrap();
     assert!(matches!(&*tenants_map, &TenantsMap::Initializing));
-    METRICS.tenant_slots.set(tenants.len() as u64);
+
     *tenants_map = TenantsMap::Open(tenants);
 
     Ok(TenantManager {
@@ -800,6 +715,7 @@ fn tenant_spawn(
         "Cannot load tenant, ignore mark found at {tenant_ignore_mark:?}"
     );
 
+    let remote_storage = resources.remote_storage.clone();
     let tenant = match Tenant::spawn(
         conf,
         tenant_shard_id,
@@ -814,7 +730,7 @@ fn tenant_spawn(
         Ok(tenant) => tenant,
         Err(e) => {
             error!("Failed to spawn tenant {tenant_shard_id}, reason: {e:#}");
-            Tenant::create_broken_tenant(conf, tenant_shard_id, format!("{e:#}"))
+            Tenant::create_broken_tenant(conf, tenant_shard_id, remote_storage, format!("{e:#}"))
         }
     };
 
@@ -824,6 +740,14 @@ fn tenant_spawn(
 async fn shutdown_all_tenants0(tenants: &std::sync::RwLock<TenantsMap>) {
     let mut join_set = JoinSet::new();
 
+    #[cfg(all(debug_assertions, not(test)))]
+    {
+        // Check that our metrics properly tracked the size of the tenants map.  This is a convenient location to check,
+        // as it happens implicitly at the end of tests etc.
+        let m = tenants.read().unwrap();
+        debug_assert_eq!(METRICS.slots_total(), m.len() as u64);
+    }
+
     // Atomically, 1. create the shutdown tasks and 2. prevent creation of new tenants.
     let (total_in_progress, total_attached) = {
         let mut m = tenants.write().unwrap();
@@ -1997,6 +1921,167 @@ impl TenantManager {
             })
             .collect())
     }
+
+    /// Completes an earlier prepared timeline detach ancestor.
+    pub(crate) async fn complete_detaching_timeline_ancestor(
+        &self,
+        tenant_shard_id: TenantShardId,
+        timeline_id: TimelineId,
+        prepared: PreparedTimelineDetach,
+        ctx: &RequestContext,
+    ) -> Result<Vec<TimelineId>, anyhow::Error> {
+        struct RevertOnDropSlot(Option<SlotGuard>);
+
+        impl Drop for RevertOnDropSlot {
+            fn drop(&mut self) {
+                if let Some(taken) = self.0.take() {
+                    taken.revert();
+                }
+            }
+        }
+
+        impl RevertOnDropSlot {
+            fn into_inner(mut self) -> SlotGuard {
+                self.0.take().unwrap()
+            }
+        }
+
+        impl std::ops::Deref for RevertOnDropSlot {
+            type Target = SlotGuard;
+
+            fn deref(&self) -> &Self::Target {
+                self.0.as_ref().unwrap()
+            }
+        }
+
+        let slot_guard = tenant_map_acquire_slot(&tenant_shard_id, TenantSlotAcquireMode::Any)?;
+        let slot_guard = RevertOnDropSlot(Some(slot_guard));
+
+        let tenant = {
+            let Some(old_slot) = slot_guard.get_old_value() else {
+                anyhow::bail!(
+                    "Tenant not found when trying to complete detaching timeline ancestor"
+                );
+            };
+
+            let Some(tenant) = old_slot.get_attached() else {
+                anyhow::bail!("Tenant is not in attached state");
+            };
+
+            if !tenant.is_active() {
+                anyhow::bail!("Tenant is not active");
+            }
+
+            tenant.clone()
+        };
+
+        let timeline = tenant.get_timeline(timeline_id, true)?;
+
+        let reparented = timeline
+            .complete_detaching_timeline_ancestor(&tenant, prepared, ctx)
+            .await?;
+
+        let mut slot_guard = slot_guard.into_inner();
+
+        let (_guard, progress) = utils::completion::channel();
+        match tenant.shutdown(progress, ShutdownMode::Hard).await {
+            Ok(()) => {
+                slot_guard.drop_old_value()?;
+            }
+            Err(_barrier) => {
+                slot_guard.revert();
+                // this really should not happen, at all, unless shutdown was already going?
+                anyhow::bail!("Cannot restart Tenant, already shutting down");
+            }
+        }
+
+        let tenant_path = self.conf.tenant_path(&tenant_shard_id);
+        let config = Tenant::load_tenant_config(self.conf, &tenant_shard_id)?;
+
+        let shard_identity = config.shard;
+        let tenant = tenant_spawn(
+            self.conf,
+            tenant_shard_id,
+            &tenant_path,
+            self.resources.clone(),
+            AttachedTenantConf::try_from(config)?,
+            shard_identity,
+            None,
+            self.tenants,
+            SpawnMode::Eager,
+            ctx,
+        )?;
+
+        slot_guard.upsert(TenantSlot::Attached(tenant))?;
+
+        Ok(reparented)
+    }
+
+    /// A page service client sends a TenantId, and to look up the correct Tenant we must
+    /// resolve this to a fully qualified TenantShardId.
+    ///
+    /// During shard splits: we shall see parent shards in InProgress state and skip them, and
+    /// instead match on child shards which should appear in Attached state.  Very early in a shard
+    /// split, or in other cases where a shard is InProgress, we will return our own InProgress result
+    /// to instruct the caller to wait for that to finish before querying again.
+    pub(crate) fn resolve_attached_shard(
+        &self,
+        tenant_id: &TenantId,
+        selector: ShardSelector,
+    ) -> ShardResolveResult {
+        let tenants = self.tenants.read().unwrap();
+        let mut want_shard = None;
+        let mut any_in_progress = None;
+
+        match &*tenants {
+            TenantsMap::Initializing => ShardResolveResult::NotFound,
+            TenantsMap::Open(m) | TenantsMap::ShuttingDown(m) => {
+                for slot in m.range(TenantShardId::tenant_range(*tenant_id)) {
+                    // Ignore all slots that don't contain an attached tenant
+                    let tenant = match &slot.1 {
+                        TenantSlot::Attached(t) => t,
+                        TenantSlot::InProgress(barrier) => {
+                            // We might still find a usable shard, but in case we don't, remember that
+                            // we saw at least one InProgress slot, so that we can distinguish this case
+                            // from a simple NotFound in our return value.
+                            any_in_progress = Some(barrier.clone());
+                            continue;
+                        }
+                        _ => continue,
+                    };
+
+                    match selector {
+                        ShardSelector::First => return ShardResolveResult::Found(tenant.clone()),
+                        ShardSelector::Zero if slot.0.shard_number == ShardNumber(0) => {
+                            return ShardResolveResult::Found(tenant.clone())
+                        }
+                        ShardSelector::Page(key) => {
+                            // First slot we see for this tenant, calculate the expected shard number
+                            // for the key: we will use this for checking if this and subsequent
+                            // slots contain the key, rather than recalculating the hash each time.
+                            if want_shard.is_none() {
+                                want_shard = Some(tenant.shard_identity.get_shard_number(&key));
+                            }
+
+                            if Some(tenant.shard_identity.number) == want_shard {
+                                return ShardResolveResult::Found(tenant.clone());
+                            }
+                        }
+                        _ => continue,
+                    }
+                }
+
+                // Fall through: we didn't find a slot that was in Attached state & matched our selector.  If
+                // we found one or more InProgress slot, indicate to caller that they should retry later.  Otherwise
+                // this requested shard simply isn't found.
+                if let Some(barrier) = any_in_progress {
+                    ShardResolveResult::InProgress(barrier)
+                } else {
+                    ShardResolveResult::NotFound
+                }
+            }
+        }
+    }
 }
 
 #[derive(Debug, thiserror::Error)]
@@ -2045,105 +2130,6 @@ pub(crate) enum GetActiveTenantError {
     Broken(String),
 }
 
-/// Get a [`Tenant`] in its active state. If the tenant_id is currently in [`TenantSlot::InProgress`]
-/// state, then wait for up to `timeout`.  If the [`Tenant`] is not currently in [`TenantState::Active`],
-/// then wait for up to `timeout` (minus however long we waited for the slot).
-pub(crate) async fn get_active_tenant_with_timeout(
-    tenant_id: TenantId,
-    shard_selector: ShardSelector,
-    timeout: Duration,
-    cancel: &CancellationToken,
-) -> Result<Arc<Tenant>, GetActiveTenantError> {
-    enum WaitFor {
-        Barrier(utils::completion::Barrier),
-        Tenant(Arc<Tenant>),
-    }
-
-    let wait_start = Instant::now();
-    let deadline = wait_start + timeout;
-
-    let (wait_for, tenant_shard_id) = {
-        let locked = TENANTS.read().unwrap();
-
-        // Resolve TenantId to TenantShardId
-        let tenant_shard_id = locked
-            .resolve_attached_shard(&tenant_id, shard_selector)
-            .ok_or(GetActiveTenantError::NotFound(GetTenantError::NotFound(
-                tenant_id,
-            )))?;
-
-        let peek_slot = tenant_map_peek_slot(&locked, &tenant_shard_id, TenantSlotPeekMode::Read)
-            .map_err(GetTenantError::MapState)?;
-        match peek_slot {
-            Some(TenantSlot::Attached(tenant)) => {
-                match tenant.current_state() {
-                    TenantState::Active => {
-                        // Fast path: we don't need to do any async waiting.
-                        return Ok(tenant.clone());
-                    }
-                    _ => {
-                        tenant.activate_now();
-                        (WaitFor::Tenant(tenant.clone()), tenant_shard_id)
-                    }
-                }
-            }
-            Some(TenantSlot::Secondary(_)) => {
-                return Err(GetActiveTenantError::NotFound(GetTenantError::NotActive(
-                    tenant_shard_id,
-                )))
-            }
-            Some(TenantSlot::InProgress(barrier)) => {
-                (WaitFor::Barrier(barrier.clone()), tenant_shard_id)
-            }
-            None => {
-                return Err(GetActiveTenantError::NotFound(GetTenantError::NotFound(
-                    tenant_id,
-                )))
-            }
-        }
-    };
-
-    let tenant = match wait_for {
-        WaitFor::Barrier(barrier) => {
-            tracing::debug!("Waiting for tenant InProgress state to pass...");
-            timeout_cancellable(
-                deadline.duration_since(Instant::now()),
-                cancel,
-                barrier.wait(),
-            )
-            .await
-            .map_err(|e| match e {
-                TimeoutCancellableError::Timeout => GetActiveTenantError::WaitForActiveTimeout {
-                    latest_state: None,
-                    wait_time: wait_start.elapsed(),
-                },
-                TimeoutCancellableError::Cancelled => GetActiveTenantError::Cancelled,
-            })?;
-            {
-                let locked = TENANTS.read().unwrap();
-                let peek_slot =
-                    tenant_map_peek_slot(&locked, &tenant_shard_id, TenantSlotPeekMode::Read)
-                        .map_err(GetTenantError::MapState)?;
-                match peek_slot {
-                    Some(TenantSlot::Attached(tenant)) => tenant.clone(),
-                    _ => {
-                        return Err(GetActiveTenantError::NotFound(GetTenantError::NotActive(
-                            tenant_shard_id,
-                        )))
-                    }
-                }
-            }
-        }
-        WaitFor::Tenant(tenant) => tenant,
-    };
-
-    tracing::debug!("Waiting for tenant to enter active state...");
-    tenant
-        .wait_to_become_active(deadline.duration_since(Instant::now()))
-        .await?;
-    Ok(tenant)
-}
-
 #[derive(Debug, thiserror::Error)]
 pub(crate) enum DeleteTimelineError {
     #[error("Tenant {0}")]
@@ -2170,7 +2156,7 @@ pub(crate) async fn load_tenant(
     tenant_id: TenantId,
     generation: Generation,
     broker_client: storage_broker::BrokerClientChannel,
-    remote_storage: Option<GenericRemoteStorage>,
+    remote_storage: GenericRemoteStorage,
     deletion_queue_client: DeletionQueueClient,
     ctx: &RequestContext,
 ) -> Result<(), TenantMapInsertError> {
@@ -2428,10 +2414,13 @@ impl SlotGuard {
                 TenantsMap::Open(m) => m,
             };
 
+            METRICS.slot_inserted(&new_value);
+
             let replaced = m.insert(self.tenant_shard_id, new_value);
             self.upserted = true;
-
-            METRICS.tenant_slots.set(m.len() as u64);
+            if let Some(replaced) = replaced.as_ref() {
+                METRICS.slot_removed(replaced);
+            }
 
             replaced
         };
@@ -2541,9 +2530,13 @@ impl Drop for SlotGuard {
                 }
 
                 if self.old_value_is_shutdown() {
+                    METRICS.slot_removed(entry.get());
                     entry.remove();
                 } else {
-                    entry.insert(self.old_value.take().unwrap());
+                    let inserting = self.old_value.take().unwrap();
+                    METRICS.slot_inserted(&inserting);
+                    let replaced = entry.insert(inserting);
+                    METRICS.slot_removed(&replaced);
                 }
             }
             Entry::Vacant(_) => {
@@ -2554,8 +2547,6 @@ impl Drop for SlotGuard {
                 );
             }
         }
-
-        METRICS.tenant_slots.set(m.len() as u64);
     }
 }
 
@@ -2635,7 +2626,9 @@ fn tenant_map_acquire_slot_impl(
             }
             _ => {
                 let (completion, barrier) = utils::completion::channel();
-                v.insert(TenantSlot::InProgress(barrier));
+                let inserting = TenantSlot::InProgress(barrier);
+                METRICS.slot_inserted(&inserting);
+                v.insert(inserting);
                 tracing::debug!("Vacant, inserted InProgress");
                 Ok(SlotGuard::new(*tenant_shard_id, None, completion))
             }
@@ -2671,7 +2664,10 @@ fn tenant_map_acquire_slot_impl(
                 _ => {
                     // Happy case: the slot was not in any state that violated our mode
                     let (completion, barrier) = utils::completion::channel();
-                    let old_value = o.insert(TenantSlot::InProgress(barrier));
+                    let in_progress = TenantSlot::InProgress(barrier);
+                    METRICS.slot_inserted(&in_progress);
+                    let old_value = o.insert(in_progress);
+                    METRICS.slot_removed(&old_value);
                     tracing::debug!("Occupied, replaced with InProgress");
                     Ok(SlotGuard::new(
                         *tenant_shard_id,
@@ -2764,86 +2760,73 @@ use {
     utils::http::error::ApiError,
 };
 
-pub(crate) fn immediate_gc(
+#[instrument(skip_all, fields(tenant_id=%tenant_shard_id.tenant_id, shard_id=%tenant_shard_id.shard_slug(), %timeline_id))]
+pub(crate) async fn immediate_gc(
     tenant_shard_id: TenantShardId,
     timeline_id: TimelineId,
     gc_req: TimelineGcRequest,
     cancel: CancellationToken,
     ctx: &RequestContext,
-) -> Result<tokio::sync::oneshot::Receiver<Result<GcResult, anyhow::Error>>, ApiError> {
-    let guard = TENANTS.read().unwrap();
-
-    let tenant = guard
-        .get(&tenant_shard_id)
-        .cloned()
-        .with_context(|| format!("tenant {tenant_shard_id}"))
-        .map_err(|e| ApiError::NotFound(e.into()))?;
+) -> Result<GcResult, ApiError> {
+    let tenant = {
+        let guard = TENANTS.read().unwrap();
+        guard
+            .get(&tenant_shard_id)
+            .cloned()
+            .with_context(|| format!("tenant {tenant_shard_id}"))
+            .map_err(|e| ApiError::NotFound(e.into()))?
+    };
 
     let gc_horizon = gc_req.gc_horizon.unwrap_or_else(|| tenant.get_gc_horizon());
     // Use tenant's pitr setting
     let pitr = tenant.get_pitr_interval();
 
+    tenant.wait_to_become_active(ACTIVE_TENANT_TIMEOUT).await?;
+
     // Run in task_mgr to avoid race with tenant_detach operation
-    let ctx = ctx.detached_child(TaskKind::GarbageCollector, DownloadBehavior::Download);
-    let (task_done, wait_task_done) = tokio::sync::oneshot::channel();
-    let span = info_span!("manual_gc", tenant_id=%tenant_shard_id.tenant_id, shard_id=%tenant_shard_id.shard_slug(), %timeline_id);
+    let ctx: RequestContext =
+        ctx.detached_child(TaskKind::GarbageCollector, DownloadBehavior::Download);
 
-    // TODO: spawning is redundant now, need to hold the gate
-    task_mgr::spawn(
-        &tokio::runtime::Handle::current(),
-        TaskKind::GarbageCollector,
-        Some(tenant_shard_id),
-        Some(timeline_id),
-        &format!("timeline_gc_handler garbage collection run for tenant {tenant_shard_id} timeline {timeline_id}"),
-        false,
-        async move {
-            fail::fail_point!("immediate_gc_task_pre");
+    let _gate_guard = tenant.gate.enter().map_err(|_| ApiError::ShuttingDown)?;
 
-            #[allow(unused_mut)]
-            let mut result = tenant
-                .gc_iteration(Some(timeline_id), gc_horizon, pitr, &cancel, &ctx)
-                .await;
-                // FIXME: `gc_iteration` can return an error for multiple reasons; we should handle it
-                // better once the types support it.
+    fail::fail_point!("immediate_gc_task_pre");
 
-            #[cfg(feature = "testing")]
-            {
-                // we need to synchronize with drop completion for python tests without polling for
-                // log messages
-                if let Ok(result) = result.as_mut() {
-                    let mut js = tokio::task::JoinSet::new();
-                    for layer in std::mem::take(&mut result.doomed_layers) {
-                        js.spawn(layer.wait_drop());
-                    }
-                    tracing::info!(total = js.len(), "starting to wait for the gc'd layers to be dropped");
-                    while let Some(res) = js.join_next().await {
-                        res.expect("wait_drop should not panic");
-                    }
-                }
+    #[allow(unused_mut)]
+    let mut result = tenant
+        .gc_iteration(Some(timeline_id), gc_horizon, pitr, &cancel, &ctx)
+        .await;
+    // FIXME: `gc_iteration` can return an error for multiple reasons; we should handle it
+    // better once the types support it.
 
-                let timeline = tenant.get_timeline(timeline_id, false).ok();
-                let rtc = timeline.as_ref().and_then(|x| x.remote_client.as_ref());
-
-                if let Some(rtc) = rtc {
-                    // layer drops schedule actions on remote timeline client to actually do the
-                    // deletions; don't care about the shutdown error, just exit fast
-                    drop(rtc.wait_completion().await);
-                }
+    #[cfg(feature = "testing")]
+    {
+        // we need to synchronize with drop completion for python tests without polling for
+        // log messages
+        if let Ok(result) = result.as_mut() {
+            let mut js = tokio::task::JoinSet::new();
+            for layer in std::mem::take(&mut result.doomed_layers) {
+                js.spawn(layer.wait_drop());
             }
-
-            match task_done.send(result) {
-                Ok(_) => (),
-                Err(result) => error!("failed to send gc result: {result:?}"),
+            tracing::info!(
+                total = js.len(),
+                "starting to wait for the gc'd layers to be dropped"
+            );
+            while let Some(res) = js.join_next().await {
+                res.expect("wait_drop should not panic");
             }
-            Ok(())
         }
-        .instrument(span)
-    );
 
-    // drop the guard until after we've spawned the task so that timeline shutdown will wait for the task
-    drop(guard);
+        let timeline = tenant.get_timeline(timeline_id, false).ok();
+        let rtc = timeline.as_ref().map(|x| &x.remote_client);
 
-    Ok(wait_task_done)
+        if let Some(rtc) = rtc {
+            // layer drops schedule actions on remote timeline client to actually do the
+            // deletions; don't care about the shutdown error, just exit fast
+            drop(rtc.wait_completion().await);
+        }
+    }
+
+    result.map_err(ApiError::InternalServerError)
 }
 
 #[cfg(test)]

pageserver/src/tenant/remote_timeline_client.rs

@@ -189,6 +189,7 @@ use camino::Utf8Path;
 use chrono::{NaiveDateTime, Utc};
 
 pub(crate) use download::download_initdb_tar_zst;
+use pageserver_api::models::AuxFilePolicy;
 use pageserver_api::shard::{ShardIndex, TenantShardId};
 use scopeguard::ScopeGuard;
 use tokio_util::sync::CancellationToken;
@@ -210,6 +211,7 @@ use tracing::{debug, error, info, instrument, warn};
 use tracing::{info_span, Instrument};
 use utils::lsn::Lsn;
 
+use crate::context::RequestContext;
 use crate::deletion_queue::{DeletionQueueClient, DeletionQueueError};
 use crate::metrics::{
     MeasureRemoteOp, RemoteOpFileKind, RemoteOpKind, RemoteTimelineClientMetrics,
@@ -239,7 +241,7 @@ use utils::id::{TenantId, TimelineId};
 use self::index::IndexPart;
 
 use super::metadata::MetadataUpdate;
-use super::storage_layer::{Layer, LayerFileName, ResidentLayer};
+use super::storage_layer::{Layer, LayerName, ResidentLayer};
 use super::upload_queue::SetDeletedFlagProgress;
 use super::Generation;
 
@@ -316,7 +318,7 @@ pub struct RemoteTimelineClient {
 
     upload_queue: Mutex<UploadQueue>,
 
-    metrics: Arc<RemoteTimelineClientMetrics>,
+    pub(crate) metrics: Arc<RemoteTimelineClientMetrics>,
 
     storage_impl: GenericRemoteStorage,
 
@@ -436,6 +438,19 @@ impl RemoteTimelineClient {
         }
     }
 
+    /// Returns true if this timeline was previously detached at this Lsn and the remote timeline
+    /// client is currently initialized.
+    pub(crate) fn is_previous_ancestor_lsn(&self, lsn: Lsn) -> bool {
+        // technically this is a dirty read, but given how timeline detach ancestor is implemented
+        // via tenant restart, the lineage has always been uploaded.
+        self.upload_queue
+            .lock()
+            .unwrap()
+            .initialized_mut()
+            .map(|uq| uq.latest_lineage.is_previous_ancestor_lsn(lsn))
+            .unwrap_or(false)
+    }
+
     fn update_remote_physical_size_gauge(&self, current_remote_index_part: Option<&IndexPart>) {
         let size: u64 = if let Some(current_remote_index_part) = current_remote_index_part {
             current_remote_index_part
@@ -447,11 +462,11 @@ impl RemoteTimelineClient {
         } else {
             0
         };
-        self.metrics.remote_physical_size_set(size);
+        self.metrics.remote_physical_size_gauge.set(size);
     }
 
     pub fn get_remote_physical_size(&self) -> u64 {
-        self.metrics.remote_physical_size_get()
+        self.metrics.remote_physical_size_gauge.get()
     }
 
     //
@@ -502,9 +517,11 @@ impl RemoteTimelineClient {
     /// On success, returns the size of the downloaded file.
     pub async fn download_layer_file(
         &self,
-        layer_file_name: &LayerFileName,
+        layer_file_name: &LayerName,
         layer_metadata: &LayerFileMetadata,
+        local_path: &Utf8Path,
         cancel: &CancellationToken,
+        ctx: &RequestContext,
     ) -> anyhow::Result<u64> {
         let downloaded_size = {
             let _unfinished_gauge_guard = self.metrics.call_begin(
@@ -521,7 +538,9 @@ impl RemoteTimelineClient {
                 self.timeline_id,
                 layer_file_name,
                 layer_metadata,
+                local_path,
                 cancel,
+                ctx,
             )
             .measure_remote_op(
                 RemoteOpFileKind::Layer,
@@ -567,7 +586,7 @@ impl RemoteTimelineClient {
         // ahead of what's _actually_ on the remote during index upload.
         upload_queue.latest_metadata = metadata.clone();
 
-        self.schedule_index_upload(upload_queue, upload_queue.latest_metadata.clone());
+        self.schedule_index_upload(upload_queue);
 
         Ok(())
     }
@@ -588,11 +607,22 @@ impl RemoteTimelineClient {
 
         upload_queue.latest_metadata.apply(update);
 
-        self.schedule_index_upload(upload_queue, upload_queue.latest_metadata.clone());
+        self.schedule_index_upload(upload_queue);
 
         Ok(())
     }
 
+    /// Launch an index-file upload operation in the background, with only aux_file_policy flag updated.
+    pub(crate) fn schedule_index_upload_for_aux_file_policy_update(
+        self: &Arc<Self>,
+        last_aux_file_policy: Option<AuxFilePolicy>,
+    ) -> anyhow::Result<()> {
+        let mut guard = self.upload_queue.lock().unwrap();
+        let upload_queue = guard.initialized_mut()?;
+        upload_queue.last_aux_file_policy = last_aux_file_policy;
+        self.schedule_index_upload(upload_queue);
+        Ok(())
+    }
     ///
     /// Launch an index-file upload operation in the background, if necessary.
     ///
@@ -608,18 +638,14 @@ impl RemoteTimelineClient {
         let upload_queue = guard.initialized_mut()?;
 
         if upload_queue.latest_files_changes_since_metadata_upload_scheduled > 0 {
-            self.schedule_index_upload(upload_queue, upload_queue.latest_metadata.clone());
+            self.schedule_index_upload(upload_queue);
         }
 
         Ok(())
     }
 
     /// Launch an index-file upload operation in the background (internal function)
-    fn schedule_index_upload(
-        self: &Arc<Self>,
-        upload_queue: &mut UploadQueueInitialized,
-        metadata: TimelineMetadata,
-    ) {
+    fn schedule_index_upload(self: &Arc<Self>, upload_queue: &mut UploadQueueInitialized) {
         let disk_consistent_lsn = upload_queue.latest_metadata.disk_consistent_lsn();
 
         info!(
@@ -628,12 +654,8 @@ impl RemoteTimelineClient {
             upload_queue.latest_files_changes_since_metadata_upload_scheduled,
         );
 
-        let index_part = IndexPart::new(
-            upload_queue.latest_files.clone(),
-            disk_consistent_lsn,
-            metadata,
-        );
-        let op = UploadOp::UploadMetadata(index_part, disk_consistent_lsn);
+        let index_part = IndexPart::from(&*upload_queue);
+        let op = UploadOp::UploadMetadata(Box::new(index_part), disk_consistent_lsn);
         self.metric_begin(&op);
         upload_queue.queued_operations.push_back(op);
         upload_queue.latest_files_changes_since_metadata_upload_scheduled = 0;
@@ -642,9 +664,67 @@ impl RemoteTimelineClient {
         self.launch_queued_tasks(upload_queue);
     }
 
+    pub(crate) async fn schedule_reparenting_and_wait(
+        self: &Arc<Self>,
+        new_parent: &TimelineId,
+    ) -> anyhow::Result<()> {
+        // FIXME: because of how Timeline::schedule_uploads works when called from layer flushing
+        // and reads the in-memory part we cannot do the detaching like this
+        let receiver = {
+            let mut guard = self.upload_queue.lock().unwrap();
+            let upload_queue = guard.initialized_mut()?;
+
+            let Some(prev) = upload_queue.latest_metadata.ancestor_timeline() else {
+                return Err(anyhow::anyhow!(
+                    "cannot reparent without a current ancestor"
+                ));
+            };
+
+            upload_queue.latest_metadata.reparent(new_parent);
+            upload_queue.latest_lineage.record_previous_ancestor(&prev);
+
+            self.schedule_index_upload(upload_queue);
+
+            self.schedule_barrier0(upload_queue)
+        };
+
+        Self::wait_completion0(receiver).await
+    }
+
+    /// Schedules uploading a new version of `index_part.json` with the given layers added,
+    /// detaching from ancestor and waits for it to complete.
     ///
-    /// Launch an upload operation in the background.
-    ///
+    /// This is used with `Timeline::detach_ancestor` functionality.
+    pub(crate) async fn schedule_adding_existing_layers_to_index_detach_and_wait(
+        self: &Arc<Self>,
+        layers: &[Layer],
+        adopted: (TimelineId, Lsn),
+    ) -> anyhow::Result<()> {
+        let barrier = {
+            let mut guard = self.upload_queue.lock().unwrap();
+            let upload_queue = guard.initialized_mut()?;
+
+            upload_queue.latest_metadata.detach_from_ancestor(&adopted);
+            upload_queue.latest_lineage.record_detaching(&adopted);
+
+            for layer in layers {
+                upload_queue
+                    .latest_files
+                    .insert(layer.layer_desc().layer_name(), layer.metadata());
+            }
+
+            self.schedule_index_upload(upload_queue);
+
+            let barrier = self.schedule_barrier0(upload_queue);
+            self.launch_queued_tasks(upload_queue);
+            barrier
+        };
+
+        Self::wait_completion0(barrier).await
+    }
+
+    /// Launch an upload operation in the background; the file is added to be included in next
+    /// `index_part.json` upload.
     pub(crate) fn schedule_layer_file_upload(
         self: &Arc<Self>,
         layer: ResidentLayer,
@@ -666,13 +746,15 @@ impl RemoteTimelineClient {
 
         upload_queue
             .latest_files
-            .insert(layer.layer_desc().filename(), metadata.clone());
+            .insert(layer.layer_desc().layer_name(), metadata.clone());
         upload_queue.latest_files_changes_since_metadata_upload_scheduled += 1;
 
         info!(
-            "scheduled layer file upload {layer} gen={:?} shard={:?}",
-            metadata.generation, metadata.shard
+            gen=?metadata.generation,
+            shard=?metadata.shard,
+            "scheduled layer file upload {layer}",
         );
+
         let op = UploadOp::UploadLayer(layer, metadata);
         self.metric_begin(&op);
         upload_queue.queued_operations.push_back(op);
@@ -688,7 +770,7 @@ impl RemoteTimelineClient {
     /// successfully.
     pub fn schedule_layer_file_deletion(
         self: &Arc<Self>,
-        names: &[LayerFileName],
+        names: &[LayerName],
     ) -> anyhow::Result<()> {
         let mut guard = self.upload_queue.lock().unwrap();
         let upload_queue = guard.initialized_mut()?;
@@ -716,7 +798,7 @@ impl RemoteTimelineClient {
         // the layer files as "dangling". this is fine, at worst case we create work for the
         // scrubber.
 
-        let names = gc_layers.iter().map(|x| x.layer_desc().filename());
+        let names = gc_layers.iter().map(|x| x.layer_desc().layer_name());
 
         self.schedule_unlinking_of_layers_from_index_part0(upload_queue, names);
 
@@ -731,14 +813,10 @@ impl RemoteTimelineClient {
         self: &Arc<Self>,
         upload_queue: &mut UploadQueueInitialized,
         names: I,
-    ) -> Vec<(LayerFileName, LayerFileMetadata)>
+    ) -> Vec<(LayerName, LayerFileMetadata)>
     where
-        I: IntoIterator<Item = LayerFileName>,
+        I: IntoIterator<Item = LayerName>,
     {
-        // Deleting layers doesn't affect the values stored in TimelineMetadata,
-        // so we don't need update it. Just serialize it.
-        let metadata = upload_queue.latest_metadata.clone();
-
         // Decorate our list of names with each name's metadata, dropping
         // names that are unexpectedly missing from our metadata.  This metadata
         // is later used when physically deleting layers, to construct key paths.
@@ -777,7 +855,7 @@ impl RemoteTimelineClient {
         // index_part update, because that needs to be uploaded before we can actually delete the
         // files.
         if upload_queue.latest_files_changes_since_metadata_upload_scheduled > 0 {
-            self.schedule_index_upload(upload_queue, metadata);
+            self.schedule_index_upload(upload_queue);
         }
 
         with_metadata
@@ -787,7 +865,7 @@ impl RemoteTimelineClient {
     /// `index_part.json` with [`Self::schedule_gc_update`] or [`Self::schedule_compaction_update`].
     pub(crate) fn schedule_deletion_of_unlinked(
         self: &Arc<Self>,
-        layers: Vec<(LayerFileName, LayerFileMetadata)>,
+        layers: Vec<(LayerName, LayerFileMetadata)>,
     ) -> anyhow::Result<()> {
         let mut guard = self.upload_queue.lock().unwrap();
         let upload_queue = guard.initialized_mut()?;
@@ -800,7 +878,7 @@ impl RemoteTimelineClient {
     fn schedule_deletion_of_unlinked0(
         self: &Arc<Self>,
         upload_queue: &mut UploadQueueInitialized,
-        mut with_metadata: Vec<(LayerFileName, LayerFileMetadata)>,
+        mut with_metadata: Vec<(LayerName, LayerFileMetadata)>,
     ) {
         // Filter out any layers which were not created by this tenant shard.  These are
         // layers that originate from some ancestor shard after a split, and may still
@@ -869,7 +947,7 @@ impl RemoteTimelineClient {
             self.schedule_layer_file_upload0(upload_queue, layer.clone());
         }
 
-        let names = compacted_from.iter().map(|x| x.layer_desc().filename());
+        let names = compacted_from.iter().map(|x| x.layer_desc().layer_name());
 
         self.schedule_unlinking_of_layers_from_index_part0(upload_queue, names);
         self.launch_queued_tasks(upload_queue);
@@ -879,12 +957,18 @@ impl RemoteTimelineClient {
 
     /// Wait for all previously scheduled uploads/deletions to complete
     pub(crate) async fn wait_completion(self: &Arc<Self>) -> anyhow::Result<()> {
-        let mut receiver = {
+        let receiver = {
             let mut guard = self.upload_queue.lock().unwrap();
             let upload_queue = guard.initialized_mut()?;
             self.schedule_barrier0(upload_queue)
         };
 
+        Self::wait_completion0(receiver).await
+    }
+
+    async fn wait_completion0(
+        mut receiver: tokio::sync::watch::Receiver<()>,
+    ) -> anyhow::Result<()> {
         if receiver.changed().await.is_err() {
             anyhow::bail!("wait_completion aborted because upload queue was stopped");
         }
@@ -1000,8 +1084,7 @@ impl RemoteTimelineClient {
             let deleted_at = Utc::now().naive_utc();
             stopped.deleted_at = SetDeletedFlagProgress::InProgress(deleted_at);
 
-            let mut index_part = IndexPart::try_from(&stopped.upload_queue_for_deletion)
-                .context("IndexPart serialize")?;
+            let mut index_part = IndexPart::from(&stopped.upload_queue_for_deletion);
             index_part.deleted_at = Some(deleted_at);
             index_part
         };
@@ -1058,6 +1141,11 @@ impl RemoteTimelineClient {
         Ok(())
     }
 
+    pub(crate) fn is_deleting(&self) -> bool {
+        let mut locked = self.upload_queue.lock().unwrap();
+        locked.stopped_mut().is_ok()
+    }
+
     pub(crate) async fn preserve_initdb_archive(
         self: &Arc<Self>,
         tenant_id: &TenantId,
@@ -1082,6 +1170,93 @@ impl RemoteTimelineClient {
         Ok(())
     }
 
+    /// Uploads the given layer **without** adding it to be part of a future `index_part.json` upload.
+    ///
+    /// This is not normally needed.
+    pub(crate) async fn upload_layer_file(
+        self: &Arc<Self>,
+        uploaded: &ResidentLayer,
+        cancel: &CancellationToken,
+    ) -> anyhow::Result<()> {
+        let remote_path = remote_layer_path(
+            &self.tenant_shard_id.tenant_id,
+            &self.timeline_id,
+            self.tenant_shard_id.to_index(),
+            &uploaded.layer_desc().layer_name(),
+            uploaded.metadata().generation,
+        );
+
+        backoff::retry(
+            || async {
+                upload::upload_timeline_layer(
+                    &self.storage_impl,
+                    uploaded.local_path(),
+                    &remote_path,
+                    uploaded.metadata().file_size(),
+                    cancel,
+                )
+                .await
+            },
+            TimeoutOrCancel::caused_by_cancel,
+            FAILED_UPLOAD_WARN_THRESHOLD,
+            FAILED_REMOTE_OP_RETRIES,
+            "upload a layer without adding it to latest files",
+            cancel,
+        )
+        .await
+        .ok_or_else(|| anyhow::Error::new(TimeoutOrCancel::Cancel))
+        .and_then(|x| x)
+        .context("upload a layer without adding it to latest files")
+    }
+
+    /// Copies the `adopted` remote existing layer to the remote path of `adopted_as`. The layer is
+    /// not added to be part of a future `index_part.json` upload.
+    pub(crate) async fn copy_timeline_layer(
+        self: &Arc<Self>,
+        adopted: &Layer,
+        adopted_as: &Layer,
+        cancel: &CancellationToken,
+    ) -> anyhow::Result<()> {
+        let source_remote_path = remote_layer_path(
+            &self.tenant_shard_id.tenant_id,
+            &adopted
+                .get_timeline_id()
+                .expect("Source timeline should be alive"),
+            self.tenant_shard_id.to_index(),
+            &adopted.layer_desc().layer_name(),
+            adopted.metadata().generation,
+        );
+
+        let target_remote_path = remote_layer_path(
+            &self.tenant_shard_id.tenant_id,
+            &self.timeline_id,
+            self.tenant_shard_id.to_index(),
+            &adopted_as.layer_desc().layer_name(),
+            adopted_as.metadata().generation,
+        );
+
+        backoff::retry(
+            || async {
+                upload::copy_timeline_layer(
+                    &self.storage_impl,
+                    &source_remote_path,
+                    &target_remote_path,
+                    cancel,
+                )
+                .await
+            },
+            TimeoutOrCancel::caused_by_cancel,
+            FAILED_UPLOAD_WARN_THRESHOLD,
+            FAILED_REMOTE_OP_RETRIES,
+            "copy timeline layer",
+            cancel,
+        )
+        .await
+        .ok_or_else(|| anyhow::Error::new(TimeoutOrCancel::Cancel))
+        .and_then(|x| x)
+        .context("remote copy timeline layer")
+    }
+
     async fn flush_deletion_queue(&self) -> Result<(), DeletionQueueError> {
         match tokio::time::timeout(
             DELETION_QUEUE_FLUSH_TIMEOUT,
@@ -1253,7 +1428,7 @@ impl RemoteTimelineClient {
         while let Some(next_op) = upload_queue.queued_operations.front() {
             // Can we run this task now?
             let can_run_now = match next_op {
-                UploadOp::UploadLayer(_, _) => {
+                UploadOp::UploadLayer(..) => {
                     // Can always be scheduled.
                     true
                 }
@@ -1380,13 +1555,25 @@ impl RemoteTimelineClient {
 
             let upload_result: anyhow::Result<()> = match &task.op {
                 UploadOp::UploadLayer(ref layer, ref layer_metadata) => {
-                    let path = layer.local_path();
+                    let local_path = layer.local_path();
+
+                    // We should only be uploading layers created by this `Tenant`'s lifetime, so
+                    // the metadata in the upload should always match our current generation.
+                    assert_eq!(layer_metadata.generation, self.generation);
+
+                    let remote_path = remote_layer_path(
+                        &self.tenant_shard_id.tenant_id,
+                        &self.timeline_id,
+                        layer_metadata.shard,
+                        &layer.layer_desc().layer_name(),
+                        layer_metadata.generation,
+                    );
+
                     upload::upload_timeline_layer(
-                        self.conf,
                         &self.storage_impl,
-                        path,
-                        layer_metadata,
-                        self.generation,
+                        local_path,
+                        &remote_path,
+                        layer_metadata.file_size(),
                         &self.cancel,
                     )
                     .measure_remote_op(
@@ -1662,6 +1849,7 @@ impl RemoteTimelineClient {
                         latest_files: initialized.latest_files.clone(),
                         latest_files_changes_since_metadata_upload_scheduled: 0,
                         latest_metadata: initialized.latest_metadata.clone(),
+                        latest_lineage: initialized.latest_lineage.clone(),
                         projected_remote_consistent_lsn: None,
                         visible_remote_consistent_lsn: initialized
                             .visible_remote_consistent_lsn
@@ -1675,6 +1863,7 @@ impl RemoteTimelineClient {
                         dangling_files: HashMap::default(),
                         shutting_down: false,
                         shutdown_ready: Arc::new(tokio::sync::Semaphore::new(0)),
+                        last_aux_file_policy: initialized.last_aux_file_policy,
                     };
 
                     let upload_queue = std::mem::replace(
@@ -1747,14 +1936,14 @@ pub fn remote_layer_path(
     tenant_id: &TenantId,
     timeline_id: &TimelineId,
     shard: ShardIndex,
-    layer_file_name: &LayerFileName,
+    layer_file_name: &LayerName,
     generation: Generation,
 ) -> RemotePath {
     // Generation-aware key format
     let path = format!(
         "tenants/{tenant_id}{0}/{TIMELINES_SEGMENT_NAME}/{timeline_id}/{1}{2}",
         shard.get_suffix(),
-        layer_file_name.file_name(),
+        layer_file_name,
         generation.get_suffix()
     );
 
@@ -1815,29 +2004,6 @@ pub fn parse_remote_index_path(path: RemotePath) -> Option<Generation> {
     }
 }
 
-/// Files on the remote storage are stored with paths, relative to the workdir.
-/// That path includes in itself both tenant and timeline ids, allowing to have a unique remote storage path.
-///
-/// Errors if the path provided does not start from pageserver's workdir.
-pub fn remote_path(
-    conf: &PageServerConf,
-    local_path: &Utf8Path,
-    generation: Generation,
-) -> anyhow::Result<RemotePath> {
-    let stripped = local_path
-        .strip_prefix(&conf.workdir)
-        .context("Failed to strip workdir prefix")?;
-
-    let suffixed = format!("{0}{1}", stripped, generation.get_suffix());
-
-    RemotePath::new(Utf8Path::new(&suffixed)).with_context(|| {
-        format!(
-            "to resolve remote part of path {:?} for base {:?}",
-            local_path, conf.workdir
-        )
-    })
-}
-
 #[cfg(test)]
 mod tests {
     use super::*;
@@ -1845,6 +2011,7 @@ mod tests {
         context::RequestContext,
         tenant::{
             harness::{TenantHarness, TIMELINE_ID},
+            storage_layer::layer::local_layer_path,
             Tenant, Timeline,
         },
         DEFAULT_PG_VERSION,
@@ -1873,8 +2040,8 @@ mod tests {
         TimelineMetadata::from_bytes(&metadata.to_bytes().unwrap()).unwrap()
     }
 
-    fn assert_file_list(a: &HashSet<LayerFileName>, b: &[&str]) {
-        let mut avec: Vec<String> = a.iter().map(|x| x.file_name()).collect();
+    fn assert_file_list(a: &HashSet<LayerName>, b: &[&str]) {
+        let mut avec: Vec<String> = a.iter().map(|x| x.to_string()).collect();
         avec.sort();
 
         let mut bvec = b.to_vec();
@@ -1985,7 +2152,7 @@ mod tests {
             tenant_ctx: _tenant_ctx,
         } = test_setup;
 
-        let client = timeline.remote_client.as_ref().unwrap();
+        let client = &timeline.remote_client;
 
         // Download back the index.json, and check that the list of files is correct
         let initial_index_part = match client
@@ -2000,7 +2167,7 @@ mod tests {
             .layer_metadata
             .keys()
             .map(|f| f.to_owned())
-            .collect::<HashSet<LayerFileName>>();
+            .collect::<HashSet<LayerName>>();
         let initial_layer = {
             assert!(initial_layers.len() == 1);
             initial_layers.into_iter().next().unwrap()
@@ -2026,12 +2193,21 @@ mod tests {
             ("000000000000000000000000000000000000-FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF__00000000016B59DA-00000000016B5A53".parse().unwrap(), dummy_contents("baz"))
         ]
         .into_iter()
-        .map(|(name, contents): (LayerFileName, Vec<u8>)| {
-            std::fs::write(timeline_path.join(name.file_name()), &contents).unwrap();
+        .map(|(name, contents): (LayerName, Vec<u8>)| {
+
+            let local_path = local_layer_path(
+                harness.conf,
+                &timeline.tenant_shard_id,
+                &timeline.timeline_id,
+                &name,
+                &generation,
+            );
+            std::fs::write(&local_path, &contents).unwrap();
 
             Layer::for_resident(
                 harness.conf,
                 &timeline,
+                local_path,
                 name,
                 LayerFileMetadata::new(contents.len() as u64, generation, shard),
             )
@@ -2098,9 +2274,9 @@ mod tests {
                 .map(|f| f.to_owned())
                 .collect(),
             &[
-                &initial_layer.file_name(),
-                &layers[0].layer_desc().filename().file_name(),
-                &layers[1].layer_desc().filename().file_name(),
+                &initial_layer.to_string(),
+                &layers[0].layer_desc().layer_name().to_string(),
+                &layers[1].layer_desc().layer_name().to_string(),
             ],
         );
         assert_eq!(index_part.metadata, metadata);
@@ -2114,7 +2290,7 @@ mod tests {
         // keep using schedule_layer_file_deletion because we don't have a way to wait for the
         // spawn_blocking started by the drop.
         client
-            .schedule_layer_file_deletion(&[layers[0].layer_desc().filename()])
+            .schedule_layer_file_deletion(&[layers[0].layer_desc().layer_name()])
             .unwrap();
         {
             let mut guard = client.upload_queue.lock().unwrap();
@@ -2132,9 +2308,9 @@ mod tests {
         }
         assert_remote_files(
             &[
-                &initial_layer.file_name(),
-                &layers[0].layer_desc().filename().file_name(),
-                &layers[1].layer_desc().filename().file_name(),
+                &initial_layer.to_string(),
+                &layers[0].layer_desc().layer_name().to_string(),
+                &layers[1].layer_desc().layer_name().to_string(),
                 "index_part.json",
             ],
             &remote_timeline_dir,
@@ -2147,9 +2323,9 @@ mod tests {
 
         assert_remote_files(
             &[
-                &initial_layer.file_name(),
-                &layers[1].layer_desc().filename().file_name(),
-                &layers[2].layer_desc().filename().file_name(),
+                &initial_layer.to_string(),
+                &layers[1].layer_desc().layer_name().to_string(),
+                &layers[2].layer_desc().layer_name().to_string(),
                 "index_part.json",
             ],
             &remote_timeline_dir,
@@ -2167,20 +2343,23 @@ mod tests {
             timeline,
             ..
         } = TestSetup::new("metrics").await.unwrap();
-        let client = timeline.remote_client.as_ref().unwrap();
-        let timeline_path = harness.timeline_path(&TIMELINE_ID);
+        let client = &timeline.remote_client;
 
-        let layer_file_name_1: LayerFileName = "000000000000000000000000000000000000-FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF__00000000016B59D8-00000000016B5A51".parse().unwrap();
+        let layer_file_name_1: LayerName = "000000000000000000000000000000000000-FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF__00000000016B59D8-00000000016B5A51".parse().unwrap();
+        let local_path = local_layer_path(
+            harness.conf,
+            &timeline.tenant_shard_id,
+            &timeline.timeline_id,
+            &layer_file_name_1,
+            &harness.generation,
+        );
         let content_1 = dummy_contents("foo");
-        std::fs::write(
-            timeline_path.join(layer_file_name_1.file_name()),
-            &content_1,
-        )
-        .unwrap();
+        std::fs::write(&local_path, &content_1).unwrap();
 
         let layer_file_1 = Layer::for_resident(
             harness.conf,
             &timeline,
+            local_path,
             layer_file_name_1.clone(),
             LayerFileMetadata::new(content_1.len() as u64, harness.generation, harness.shard),
         );
@@ -2249,12 +2428,7 @@ mod tests {
 
     async fn inject_index_part(test_state: &TestSetup, generation: Generation) -> IndexPart {
         // An empty IndexPart, just sufficient to ensure deserialization will succeed
-        let example_metadata = TimelineMetadata::example();
-        let example_index_part = IndexPart::new(
-            HashMap::new(),
-            example_metadata.disk_consistent_lsn(),
-            example_metadata,
-        );
+        let example_index_part = IndexPart::example();
 
         let index_part_bytes = serde_json::to_vec(&example_index_part).unwrap();
 

pageserver/src/tenant/remote_timeline_client/download.rs

@@ -18,9 +18,10 @@ use tracing::warn;
 use utils::backoff;
 
 use crate::config::PageServerConf;
+use crate::context::RequestContext;
 use crate::span::debug_assert_current_span_has_tenant_and_timeline_id;
 use crate::tenant::remote_timeline_client::{remote_layer_path, remote_timelines_path};
-use crate::tenant::storage_layer::LayerFileName;
+use crate::tenant::storage_layer::LayerName;
 use crate::tenant::Generation;
 use crate::virtual_file::{on_fatal_io_error, MaybeFatalIo, VirtualFile};
 use crate::TEMP_FILE_SUFFIX;
@@ -40,19 +41,21 @@ use super::{
 /// in the metadata. (In the future, we might do more cross-checks, like CRC validation)
 ///
 /// Returns the size of the downloaded file.
+#[allow(clippy::too_many_arguments)]
 pub async fn download_layer_file<'a>(
     conf: &'static PageServerConf,
     storage: &'a GenericRemoteStorage,
     tenant_shard_id: TenantShardId,
     timeline_id: TimelineId,
-    layer_file_name: &'a LayerFileName,
+    layer_file_name: &'a LayerName,
     layer_metadata: &'a LayerFileMetadata,
+    local_path: &Utf8Path,
     cancel: &CancellationToken,
+    ctx: &RequestContext,
 ) -> Result<u64, DownloadError> {
     debug_assert_current_span_has_tenant_and_timeline_id();
 
     let timeline_path = conf.timeline_path(&tenant_shard_id, &timeline_id);
-    let local_path = timeline_path.join(layer_file_name.file_name());
 
     let remote_path = remote_layer_path(
         &tenant_shard_id.tenant_id,
@@ -72,10 +75,10 @@ pub async fn download_layer_file<'a>(
     // For more context about durable_rename check this email from postgres mailing list:
     // https://www.postgresql.org/message-id/56583BDD.9060302@2ndquadrant.com
     // If pageserver crashes the temp file will be deleted on startup and re-downloaded.
-    let temp_file_path = path_with_suffix_extension(&local_path, TEMP_DOWNLOAD_EXTENSION);
+    let temp_file_path = path_with_suffix_extension(local_path, TEMP_DOWNLOAD_EXTENSION);
 
     let bytes_amount = download_retry(
-        || async { download_object(storage, &remote_path, &temp_file_path, cancel).await },
+        || async { download_object(storage, &remote_path, &temp_file_path, cancel, ctx).await },
         &format!("download {remote_path:?}"),
         cancel,
     )
@@ -102,14 +105,17 @@ pub async fn download_layer_file<'a>(
     // We use fatal_err() below because the after the rename above,
     // the in-memory state of the filesystem already has the layer file in its final place,
     // and subsequent pageserver code could think it's durable while it really isn't.
-    let work = async move {
-        let timeline_dir = VirtualFile::open(&timeline_path)
-            .await
-            .fatal_err("VirtualFile::open for timeline dir fsync");
-        timeline_dir
-            .sync_all()
-            .await
-            .fatal_err("VirtualFile::sync_all timeline dir");
+    let work = {
+        let ctx = ctx.detached_child(ctx.task_kind(), ctx.download_behavior());
+        async move {
+            let timeline_dir = VirtualFile::open(&timeline_path, &ctx)
+                .await
+                .fatal_err("VirtualFile::open for timeline dir fsync");
+            timeline_dir
+                .sync_all()
+                .await
+                .fatal_err("VirtualFile::sync_all timeline dir");
+        }
     };
     crate::virtual_file::io_engine::get()
         .spawn_blocking_and_block_on_if_std(work)
@@ -133,6 +139,7 @@ async fn download_object<'a>(
     src_path: &RemotePath,
     dst_path: &Utf8PathBuf,
     cancel: &CancellationToken,
+    #[cfg_attr(target_os = "macos", allow(unused_variables))] ctx: &RequestContext,
 ) -> Result<u64, DownloadError> {
     let res = match crate::virtual_file::io_engine::get() {
         crate::virtual_file::io_engine::IoEngine::NotSet => panic!("unset"),
@@ -185,7 +192,7 @@ async fn download_object<'a>(
             use crate::virtual_file::owned_buffers_io::{self, util::size_tracking_writer};
             use bytes::BytesMut;
             async {
-                let destination_file = VirtualFile::create(dst_path)
+                let destination_file = VirtualFile::create(dst_path, ctx)
                     .await
                     .with_context(|| format!("create a destination file for layer '{dst_path}'"))
                     .map_err(DownloadError::Other)?;
@@ -208,10 +215,10 @@ async fn download_object<'a>(
                             Err(e) => return Err(e),
                         };
                         buffered
-                            .write_buffered(tokio_epoll_uring::BoundedBuf::slice_full(chunk))
+                            .write_buffered(tokio_epoll_uring::BoundedBuf::slice_full(chunk), ctx)
                             .await?;
                     }
-                    let size_tracking = buffered.flush_and_into_inner().await?;
+                    let size_tracking = buffered.flush_and_into_inner(ctx).await?;
                     Ok(size_tracking.into_inner())
                 }
                 .await?;

pageserver/src/tenant/remote_timeline_client/index.rs

@@ -5,11 +5,12 @@
 use std::collections::HashMap;
 
 use chrono::NaiveDateTime;
+use pageserver_api::models::AuxFilePolicy;
 use serde::{Deserialize, Serialize};
-use utils::bin_ser::SerializeError;
+use utils::id::TimelineId;
 
 use crate::tenant::metadata::TimelineMetadata;
-use crate::tenant::storage_layer::LayerFileName;
+use crate::tenant::storage_layer::LayerName;
 use crate::tenant::upload_queue::UploadQueueInitialized;
 use crate::tenant::Generation;
 use pageserver_api::shard::ShardIndex;
@@ -76,7 +77,7 @@ pub struct IndexPart {
     ///
     /// Older versions of `IndexPart` will not have this property or have only a part of metadata
     /// that latest version stores.
-    pub layer_metadata: HashMap<LayerFileName, IndexLayerMetadata>,
+    pub layer_metadata: HashMap<LayerName, IndexLayerMetadata>,
 
     // 'disk_consistent_lsn' is a copy of the 'disk_consistent_lsn' in the metadata.
     // It's duplicated for convenience when reading the serialized structure, but is
@@ -85,6 +86,19 @@ pub struct IndexPart {
 
     #[serde(rename = "metadata_bytes")]
     pub metadata: TimelineMetadata,
+
+    #[serde(default)]
+    pub(crate) lineage: Lineage,
+
+    /// Describes the kind of aux files stored in the timeline.
+    ///
+    /// The value is modified during file ingestion when the latest wanted value communicated via tenant config is applied if it is acceptable.
+    /// A V1 setting after V2 files have been committed is not accepted.
+    ///
+    /// None means no aux files have been written to the storage before the point
+    /// when this flag is introduced.
+    #[serde(skip_serializing_if = "Option::is_none", default)]
+    pub(crate) last_aux_file_policy: Option<AuxFilePolicy>,
 }
 
 impl IndexPart {
@@ -97,22 +111,25 @@ impl IndexPart {
     /// - 3: no longer deserialize `timeline_layers` (serialized format is the same, but timeline_layers
     ///      is always generated from the keys of `layer_metadata`)
     /// - 4: timeline_layers is fully removed.
-    const LATEST_VERSION: usize = 4;
+    /// - 5: lineage was added
+    /// - 6: last_aux_file_policy is added.
+    const LATEST_VERSION: usize = 6;
 
     // Versions we may see when reading from a bucket.
-    pub const KNOWN_VERSIONS: &'static [usize] = &[1, 2, 3, 4];
+    pub const KNOWN_VERSIONS: &'static [usize] = &[1, 2, 3, 4, 5, 6];
 
     pub const FILE_NAME: &'static str = "index_part.json";
 
-    pub fn new(
-        layers_and_metadata: HashMap<LayerFileName, LayerFileMetadata>,
+    fn new(
+        layers_and_metadata: &HashMap<LayerName, LayerFileMetadata>,
         disk_consistent_lsn: Lsn,
         metadata: TimelineMetadata,
+        lineage: Lineage,
+        last_aux_file_policy: Option<AuxFilePolicy>,
     ) -> Self {
-        // Transform LayerFileMetadata into IndexLayerMetadata
         let layer_metadata = layers_and_metadata
-            .into_iter()
-            .map(|(k, v)| (k, IndexLayerMetadata::from(v)))
+            .iter()
+            .map(|(k, v)| (k.to_owned(), IndexLayerMetadata::from(v)))
             .collect();
 
         Self {
@@ -121,6 +138,8 @@ impl IndexPart {
             disk_consistent_lsn,
             metadata,
             deleted_at: None,
+            lineage,
+            last_aux_file_policy,
         }
     }
 
@@ -141,20 +160,37 @@ impl IndexPart {
     pub fn to_s3_bytes(&self) -> serde_json::Result<Vec<u8>> {
         serde_json::to_vec(self)
     }
+
+    #[cfg(test)]
+    pub(crate) fn example() -> Self {
+        let example_metadata = TimelineMetadata::example();
+        Self::new(
+            &HashMap::new(),
+            example_metadata.disk_consistent_lsn(),
+            example_metadata,
+            Default::default(),
+            Some(AuxFilePolicy::V1),
+        )
+    }
+
+    pub(crate) fn last_aux_file_policy(&self) -> Option<AuxFilePolicy> {
+        self.last_aux_file_policy
+    }
 }
 
-impl TryFrom<&UploadQueueInitialized> for IndexPart {
-    type Error = SerializeError;
+impl From<&UploadQueueInitialized> for IndexPart {
+    fn from(uq: &UploadQueueInitialized) -> Self {
+        let disk_consistent_lsn = uq.latest_metadata.disk_consistent_lsn();
+        let metadata = uq.latest_metadata.clone();
+        let lineage = uq.latest_lineage.clone();
 
-    fn try_from(upload_queue: &UploadQueueInitialized) -> Result<Self, Self::Error> {
-        let disk_consistent_lsn = upload_queue.latest_metadata.disk_consistent_lsn();
-        let metadata = upload_queue.latest_metadata.clone();
-
-        Ok(Self::new(
-            upload_queue.latest_files.clone(),
+        Self::new(
+            &uq.latest_files,
             disk_consistent_lsn,
             metadata,
-        ))
+            lineage,
+            uq.last_aux_file_policy,
+        )
     }
 }
 
@@ -172,8 +208,8 @@ pub struct IndexLayerMetadata {
     pub shard: ShardIndex,
 }
 
-impl From<LayerFileMetadata> for IndexLayerMetadata {
-    fn from(other: LayerFileMetadata) -> Self {
+impl From<&LayerFileMetadata> for IndexLayerMetadata {
+    fn from(other: &LayerFileMetadata) -> Self {
         IndexLayerMetadata {
             file_size: other.file_size,
             generation: other.generation,
@@ -182,8 +218,76 @@ impl From<LayerFileMetadata> for IndexLayerMetadata {
     }
 }
 
+/// Limited history of earlier ancestors.
+///
+/// A timeline can have more than 1 earlier ancestor, in the rare case that it was repeatedly
+/// reparented by having an later timeline be detached from it's ancestor.
+#[derive(Debug, PartialEq, Eq, Clone, Serialize, Deserialize, Default)]
+pub(crate) struct Lineage {
+    /// Has the `reparenting_history` been truncated to [`Lineage::REMEMBER_AT_MOST`].
+    #[serde(skip_serializing_if = "is_false", default)]
+    reparenting_history_truncated: bool,
+
+    /// Earlier ancestors, truncated when [`Self::reparenting_history_truncated`]
+    ///
+    /// These are stored in case we want to support WAL based DR on the timeline. There can be many
+    /// of these and at most one [`Self::original_ancestor`]. There cannot be more reparentings
+    /// after [`Self::original_ancestor`] has been set.
+    #[serde(skip_serializing_if = "Vec::is_empty", default)]
+    reparenting_history: Vec<TimelineId>,
+
+    /// The ancestor from which this timeline has been detached from and when.
+    ///
+    /// If you are adding support for detaching from a hierarchy, consider changing the ancestry
+    /// into a `Vec<(TimelineId, Lsn)>` to be a path instead.
+    #[serde(skip_serializing_if = "Option::is_none", default)]
+    original_ancestor: Option<(TimelineId, Lsn, NaiveDateTime)>,
+}
+
+fn is_false(b: &bool) -> bool {
+    !b
+}
+
+impl Lineage {
+    const REMEMBER_AT_MOST: usize = 100;
+
+    pub(crate) fn record_previous_ancestor(&mut self, old_ancestor: &TimelineId) {
+        if self.reparenting_history.last() == Some(old_ancestor) {
+            // do not re-record it
+            return;
+        }
+
+        let drop_oldest = self.reparenting_history.len() + 1 >= Self::REMEMBER_AT_MOST;
+
+        self.reparenting_history_truncated |= drop_oldest;
+        if drop_oldest {
+            self.reparenting_history.remove(0);
+        }
+        self.reparenting_history.push(*old_ancestor);
+    }
+
+    pub(crate) fn record_detaching(&mut self, branchpoint: &(TimelineId, Lsn)) {
+        assert!(self.original_ancestor.is_none());
+
+        self.original_ancestor =
+            Some((branchpoint.0, branchpoint.1, chrono::Utc::now().naive_utc()));
+    }
+
+    /// The queried lsn is most likely the basebackup lsn, and this answers question "is it allowed
+    /// to start a read/write primary at this lsn".
+    ///
+    /// Returns true if the Lsn was previously a branch point.
+    pub(crate) fn is_previous_ancestor_lsn(&self, lsn: Lsn) -> bool {
+        self.original_ancestor
+            .as_ref()
+            .is_some_and(|(_, ancestor_lsn, _)| lsn == *ancestor_lsn)
+    }
+}
+
 #[cfg(test)]
 mod tests {
+    use std::str::FromStr;
+
     use super::*;
 
     #[test]
@@ -219,6 +323,8 @@ mod tests {
             disk_consistent_lsn: "0/16960E8".parse::<Lsn>().unwrap(),
             metadata: TimelineMetadata::from_bytes(&[113,11,159,210,0,54,0,4,0,0,0,0,1,105,96,232,1,0,0,0,0,1,105,96,112,0,0,0,0,0,0,0,0,0,0,0,0,0,1,105,96,112,0,0,0,0,1,105,96,112,0,0,0,14,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0]).unwrap(),
             deleted_at: None,
+            lineage: Lineage::default(),
+            last_aux_file_policy: None,
         };
 
         let part = IndexPart::from_s3_bytes(example.as_bytes()).unwrap();
@@ -259,6 +365,8 @@ mod tests {
             disk_consistent_lsn: "0/16960E8".parse::<Lsn>().unwrap(),
             metadata: TimelineMetadata::from_bytes(&[113,11,159,210,0,54,0,4,0,0,0,0,1,105,96,232,1,0,0,0,0,1,105,96,112,0,0,0,0,0,0,0,0,0,0,0,0,0,1,105,96,112,0,0,0,0,1,105,96,112,0,0,0,14,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0]).unwrap(),
             deleted_at: None,
+            lineage: Lineage::default(),
+            last_aux_file_policy: None,
         };
 
         let part = IndexPart::from_s3_bytes(example.as_bytes()).unwrap();
@@ -300,7 +408,9 @@ mod tests {
             disk_consistent_lsn: "0/16960E8".parse::<Lsn>().unwrap(),
             metadata: TimelineMetadata::from_bytes(&[113,11,159,210,0,54,0,4,0,0,0,0,1,105,96,232,1,0,0,0,0,1,105,96,112,0,0,0,0,0,0,0,0,0,0,0,0,0,1,105,96,112,0,0,0,0,1,105,96,112,0,0,0,14,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0]).unwrap(),
             deleted_at: Some(chrono::NaiveDateTime::parse_from_str(
-                "2023-07-31T09:00:00.123000000", "%Y-%m-%dT%H:%M:%S.%f").unwrap())
+                "2023-07-31T09:00:00.123000000", "%Y-%m-%dT%H:%M:%S.%f").unwrap()),
+            lineage: Lineage::default(),
+            last_aux_file_policy: None,
         };
 
         let part = IndexPart::from_s3_bytes(example.as_bytes()).unwrap();
@@ -345,6 +455,8 @@ mod tests {
             ])
             .unwrap(),
             deleted_at: None,
+            lineage: Lineage::default(),
+            last_aux_file_policy: None,
         };
 
         let empty_layers_parsed = IndexPart::from_s3_bytes(empty_layers_json.as_bytes()).unwrap();
@@ -383,11 +495,110 @@ mod tests {
             ]),
             disk_consistent_lsn: "0/16960E8".parse::<Lsn>().unwrap(),
             metadata: TimelineMetadata::from_bytes(&[113,11,159,210,0,54,0,4,0,0,0,0,1,105,96,232,1,0,0,0,0,1,105,96,112,0,0,0,0,0,0,0,0,0,0,0,0,0,1,105,96,112,0,0,0,0,1,105,96,112,0,0,0,14,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0]).unwrap(),
-            deleted_at: Some(chrono::NaiveDateTime::parse_from_str(
-                "2023-07-31T09:00:00.123000000", "%Y-%m-%dT%H:%M:%S.%f").unwrap()),
+            deleted_at: Some(parse_naive_datetime("2023-07-31T09:00:00.123000000")),
+            lineage: Lineage::default(),
+            last_aux_file_policy: None,
         };
 
         let part = IndexPart::from_s3_bytes(example.as_bytes()).unwrap();
         assert_eq!(part, expected);
     }
+
+    #[test]
+    fn v5_indexpart_is_parsed() {
+        let example = r#"{
+            "version":5,
+            "layer_metadata":{
+                "000000000000000000000000000000000000-FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF__00000000014EF420-00000000014EF499":{"file_size":23289856,"generation":1},
+                "000000000000000000000000000000000000-FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF__00000000014EF499-00000000015A7619":{"file_size":1015808,"generation":1}},
+                "disk_consistent_lsn":"0/15A7618",
+                "metadata_bytes":[226,88,25,241,0,46,0,4,0,0,0,0,1,90,118,24,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,78,244,32,0,0,0,0,1,78,244,32,0,0,0,16,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0],
+                "lineage":{
+                    "original_ancestor":["e2bfd8c633d713d279e6fcd2bcc15b6d","0/15A7618","2024-05-07T18:52:36.322426563"],
+                    "reparenting_history":["e1bfd8c633d713d279e6fcd2bcc15b6d"]
+                }
+        }"#;
+
+        let expected = IndexPart {
+            version: 5,
+            layer_metadata: HashMap::from([
+                ("000000000000000000000000000000000000-FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF__00000000014EF420-00000000014EF499".parse().unwrap(), IndexLayerMetadata {
+                    file_size: 23289856,
+                    generation: Generation::new(1),
+                    shard: ShardIndex::unsharded(),
+                }),
+                ("000000000000000000000000000000000000-FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF__00000000014EF499-00000000015A7619".parse().unwrap(), IndexLayerMetadata {
+                    file_size: 1015808,
+                    generation: Generation::new(1),
+                    shard: ShardIndex::unsharded(),
+                })
+            ]),
+            disk_consistent_lsn: Lsn::from_str("0/15A7618").unwrap(),
+            metadata: TimelineMetadata::from_bytes(&[226,88,25,241,0,46,0,4,0,0,0,0,1,90,118,24,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,78,244,32,0,0,0,0,1,78,244,32,0,0,0,16,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0]).unwrap(),
+            deleted_at: None,
+            lineage: Lineage {
+                reparenting_history_truncated: false,
+                reparenting_history: vec![TimelineId::from_str("e1bfd8c633d713d279e6fcd2bcc15b6d").unwrap()],
+                original_ancestor: Some((TimelineId::from_str("e2bfd8c633d713d279e6fcd2bcc15b6d").unwrap(), Lsn::from_str("0/15A7618").unwrap(), parse_naive_datetime("2024-05-07T18:52:36.322426563"))),
+            },
+            last_aux_file_policy: None,
+        };
+
+        let part = IndexPart::from_s3_bytes(example.as_bytes()).unwrap();
+        assert_eq!(part, expected);
+    }
+
+    #[test]
+    fn v6_indexpart_is_parsed() {
+        let example = r#"{
+            "version":6,
+            "layer_metadata":{
+                "000000000000000000000000000000000000-FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF__0000000001696070-00000000016960E9": { "file_size": 25600000 },
+                "000000000000000000000000000000000000-FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF__00000000016B59D8-00000000016B5A51": { "file_size": 9007199254741001 }
+            },
+            "disk_consistent_lsn":"0/16960E8",
+            "metadata_bytes":[113,11,159,210,0,54,0,4,0,0,0,0,1,105,96,232,1,0,0,0,0,1,105,96,112,0,0,0,0,0,0,0,0,0,0,0,0,0,1,105,96,112,0,0,0,0,1,105,96,112,0,0,0,14,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0],
+            "deleted_at": "2023-07-31T09:00:00.123",
+            "lineage":{
+                "original_ancestor":["e2bfd8c633d713d279e6fcd2bcc15b6d","0/15A7618","2024-05-07T18:52:36.322426563"],
+                "reparenting_history":["e1bfd8c633d713d279e6fcd2bcc15b6d"]
+            },
+            "last_aux_file_policy": "V2"
+        }"#;
+
+        let expected = IndexPart {
+            version: 6,
+            layer_metadata: HashMap::from([
+                ("000000000000000000000000000000000000-FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF__0000000001696070-00000000016960E9".parse().unwrap(), IndexLayerMetadata {
+                    file_size: 25600000,
+                    generation: Generation::none(),
+                    shard: ShardIndex::unsharded()
+                }),
+                ("000000000000000000000000000000000000-FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF__00000000016B59D8-00000000016B5A51".parse().unwrap(), IndexLayerMetadata {
+                    // serde_json should always parse this but this might be a double with jq for
+                    // example.
+                    file_size: 9007199254741001,
+                    generation: Generation::none(),
+                    shard: ShardIndex::unsharded()
+                })
+            ]),
+            disk_consistent_lsn: "0/16960E8".parse::<Lsn>().unwrap(),
+            metadata: TimelineMetadata::from_bytes(&[113,11,159,210,0,54,0,4,0,0,0,0,1,105,96,232,1,0,0,0,0,1,105,96,112,0,0,0,0,0,0,0,0,0,0,0,0,0,1,105,96,112,0,0,0,0,1,105,96,112,0,0,0,14,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0]).unwrap(),
+            deleted_at: Some(chrono::NaiveDateTime::parse_from_str(
+                "2023-07-31T09:00:00.123000000", "%Y-%m-%dT%H:%M:%S.%f").unwrap()),
+            lineage: Lineage {
+                reparenting_history_truncated: false,
+                reparenting_history: vec![TimelineId::from_str("e1bfd8c633d713d279e6fcd2bcc15b6d").unwrap()],
+                original_ancestor: Some((TimelineId::from_str("e2bfd8c633d713d279e6fcd2bcc15b6d").unwrap(), Lsn::from_str("0/15A7618").unwrap(), parse_naive_datetime("2024-05-07T18:52:36.322426563"))),
+            },
+            last_aux_file_policy: Some(AuxFilePolicy::V2),
+        };
+
+        let part = IndexPart::from_s3_bytes(example.as_bytes()).unwrap();
+        assert_eq!(part, expected);
+    }
+
+    fn parse_naive_datetime(s: &str) -> NaiveDateTime {
+        chrono::NaiveDateTime::parse_from_str(s, "%Y-%m-%dT%H:%M:%S.%f").unwrap()
+    }
 }

pageserver/src/tenant/remote_timeline_client/upload.rs

@@ -12,18 +12,13 @@ use tokio_util::sync::CancellationToken;
 use utils::backoff;
 
 use super::Generation;
-use crate::{
-    config::PageServerConf,
-    tenant::remote_timeline_client::{
-        index::IndexPart, remote_index_path, remote_initdb_archive_path,
-        remote_initdb_preserved_archive_path, remote_path,
-    },
+use crate::tenant::remote_timeline_client::{
+    index::IndexPart, remote_index_path, remote_initdb_archive_path,
+    remote_initdb_preserved_archive_path,
 };
-use remote_storage::{GenericRemoteStorage, TimeTravelError};
+use remote_storage::{GenericRemoteStorage, RemotePath, TimeTravelError};
 use utils::id::{TenantId, TimelineId};
 
-use super::index::LayerFileMetadata;
-
 use tracing::info;
 
 /// Serializes and uploads the given index part data to the remote storage.
@@ -65,11 +60,10 @@ pub(crate) async fn upload_index_part<'a>(
 ///
 /// On an error, bumps the retries count and reschedules the entire task.
 pub(super) async fn upload_timeline_layer<'a>(
-    conf: &'static PageServerConf,
     storage: &'a GenericRemoteStorage,
-    source_path: &'a Utf8Path,
-    known_metadata: &'a LayerFileMetadata,
-    generation: Generation,
+    local_path: &'a Utf8Path,
+    remote_path: &'a RemotePath,
+    metadata_size: u64,
     cancel: &CancellationToken,
 ) -> anyhow::Result<()> {
     fail_point!("before-upload-layer", |_| {
@@ -78,8 +72,7 @@ pub(super) async fn upload_timeline_layer<'a>(
 
     pausable_failpoint!("before-upload-layer-pausable");
 
-    let storage_path = remote_path(conf, source_path, generation)?;
-    let source_file_res = fs::File::open(&source_path).await;
+    let source_file_res = fs::File::open(&local_path).await;
     let source_file = match source_file_res {
         Ok(source_file) => source_file,
         Err(e) if e.kind() == ErrorKind::NotFound => {
@@ -90,34 +83,49 @@ pub(super) async fn upload_timeline_layer<'a>(
             // it has been written to disk yet.
             //
             // This is tested against `test_compaction_delete_before_upload`
-            info!(path = %source_path, "File to upload doesn't exist. Likely the file has been deleted and an upload is not required any more.");
+            info!(path = %local_path, "File to upload doesn't exist. Likely the file has been deleted and an upload is not required any more.");
             return Ok(());
         }
-        Err(e) => {
-            Err(e).with_context(|| format!("open a source file for layer {source_path:?}"))?
-        }
+        Err(e) => Err(e).with_context(|| format!("open a source file for layer {local_path:?}"))?,
     };
 
     let fs_size = source_file
         .metadata()
         .await
-        .with_context(|| format!("get the source file metadata for layer {source_path:?}"))?
+        .with_context(|| format!("get the source file metadata for layer {local_path:?}"))?
         .len();
 
-    let metadata_size = known_metadata.file_size();
     if metadata_size != fs_size {
-        bail!("File {source_path:?} has its current FS size {fs_size} diferent from initially determined {metadata_size}");
+        bail!("File {local_path:?} has its current FS size {fs_size} diferent from initially determined {metadata_size}");
     }
 
     let fs_size = usize::try_from(fs_size)
-        .with_context(|| format!("convert {source_path:?} size {fs_size} usize"))?;
+        .with_context(|| format!("convert {local_path:?} size {fs_size} usize"))?;
 
     let reader = tokio_util::io::ReaderStream::with_capacity(source_file, super::BUFFER_SIZE);
 
     storage
-        .upload(reader, fs_size, &storage_path, None, cancel)
+        .upload(reader, fs_size, remote_path, None, cancel)
         .await
-        .with_context(|| format!("upload layer from local path '{source_path}'"))
+        .with_context(|| format!("upload layer from local path '{local_path}'"))
+}
+
+pub(super) async fn copy_timeline_layer(
+    storage: &GenericRemoteStorage,
+    source_path: &RemotePath,
+    target_path: &RemotePath,
+    cancel: &CancellationToken,
+) -> anyhow::Result<()> {
+    fail_point!("before-copy-layer", |_| {
+        bail!("failpoint before-copy-layer")
+    });
+
+    pausable_failpoint!("before-copy-layer-pausable");
+
+    storage
+        .copy_object(source_path, target_path, cancel)
+        .await
+        .with_context(|| format!("copy layer {source_path} to {target_path}"))
 }
 
 /// Uploads the given `initdb` data to the remote storage.

pageserver/src/tenant/secondary.rs

@@ -6,10 +6,9 @@ mod scheduler;
 use std::{sync::Arc, time::SystemTime};
 
 use crate::{
-    config::PageServerConf,
+    context::RequestContext,
     disk_usage_eviction_task::DiskUsageEvictionInfo,
     task_mgr::{self, TaskKind, BACKGROUND_RUNTIME},
-    virtual_file::MaybeFatalIo,
 };
 
 use self::{
@@ -21,7 +20,7 @@ use super::{
     config::{SecondaryLocationConfig, TenantConfOpt},
     mgr::TenantManager,
     span::debug_assert_current_span_has_tenant_id,
-    storage_layer::LayerFileName,
+    storage_layer::LayerName,
 };
 
 use pageserver_api::{
@@ -176,12 +175,7 @@ impl SecondaryTenant {
 
     /// Cancellation safe, but on cancellation the eviction will go through
     #[instrument(skip_all, fields(tenant_id=%self.tenant_shard_id.tenant_id, shard_id=%self.tenant_shard_id.shard_slug(), timeline_id=%timeline_id, name=%name))]
-    pub(crate) async fn evict_layer(
-        self: &Arc<Self>,
-        conf: &PageServerConf,
-        timeline_id: TimelineId,
-        name: LayerFileName,
-    ) {
+    pub(crate) async fn evict_layer(self: &Arc<Self>, timeline_id: TimelineId, name: LayerName) {
         debug_assert_current_span_has_tenant_id();
 
         let guard = match self.gate.enter() {
@@ -194,37 +188,11 @@ impl SecondaryTenant {
 
         let now = SystemTime::now();
 
-        let path = conf
-            .timeline_path(&self.tenant_shard_id, &timeline_id)
-            .join(name.file_name());
-
         let this = self.clone();
 
         // spawn it to be cancellation safe
         tokio::task::spawn_blocking(move || {
             let _guard = guard;
-            // We tolerate ENOENT, because between planning eviction and executing
-            // it, the secondary downloader could have seen an updated heatmap that
-            // resulted in a layer being deleted.
-            // Other local I/O errors are process-fatal: these should never happen.
-            let deleted = std::fs::remove_file(path);
-
-            let not_found = deleted
-                .as_ref()
-                .is_err_and(|x| x.kind() == std::io::ErrorKind::NotFound);
-
-            let deleted = if not_found {
-                false
-            } else {
-                deleted
-                    .map(|()| true)
-                    .fatal_err("Deleting layer during eviction")
-            };
-
-            if !deleted {
-                // skip updating accounting and putting perhaps later timestamp
-                return;
-            }
 
             // Update the timeline's state.  This does not have to be synchronized with
             // the download process, because:
@@ -243,8 +211,15 @@ impl SecondaryTenant {
             // of the cache.
             let mut detail = this.detail.lock().unwrap();
             if let Some(timeline_detail) = detail.timelines.get_mut(&timeline_id) {
-                timeline_detail.on_disk_layers.remove(&name);
-                timeline_detail.evicted_at.insert(name, now);
+                let removed = timeline_detail.on_disk_layers.remove(&name);
+
+                // We might race with removal of the same layer during downloads, if it was removed
+                // from the heatmap.  If we see that the OnDiskState is gone, then no need to
+                // do a physical deletion or store in evicted_at.
+                if let Some(removed) = removed {
+                    removed.remove_blocking();
+                    timeline_detail.evicted_at.insert(name, now);
+                }
             }
         })
         .await
@@ -316,9 +291,13 @@ pub fn spawn_tasks(
     let (upload_req_tx, upload_req_rx) =
         tokio::sync::mpsc::channel::<CommandRequest<UploadCommand>>(16);
 
+    let downloader_task_ctx = RequestContext::new(
+        TaskKind::SecondaryDownloads,
+        crate::context::DownloadBehavior::Download,
+    );
     task_mgr::spawn(
         BACKGROUND_RUNTIME.handle(),
-        TaskKind::SecondaryDownloads,
+        downloader_task_ctx.task_kind(),
         None,
         None,
         "secondary tenant downloads",
@@ -330,6 +309,7 @@ pub fn spawn_tasks(
                 download_req_rx,
                 bg_jobs_clone,
                 cancel_clone,
+                downloader_task_ctx,
             )
             .await;
 

pageserver/src/tenant/secondary/downloader.rs

@@ -8,6 +8,7 @@ use std::{
 
 use crate::{
     config::PageServerConf,
+    context::RequestContext,
     disk_usage_eviction_task::{
         finite_f32, DiskUsageEvictionInfo, EvictionCandidate, EvictionLayer, EvictionSecondaryLayer,
     },
@@ -21,16 +22,19 @@ use crate::{
             FAILED_REMOTE_OP_RETRIES,
         },
         span::debug_assert_current_span_has_tenant_id,
-        storage_layer::LayerFileName,
+        storage_layer::{layer::local_layer_path, LayerName},
         tasks::{warn_when_period_overrun, BackgroundLoopKind},
     },
     virtual_file::{on_fatal_io_error, MaybeFatalIo, VirtualFile},
-    METADATA_FILE_NAME, TEMP_FILE_SUFFIX,
+    TEMP_FILE_SUFFIX,
 };
 
 use super::{
     heatmap::HeatMapLayer,
-    scheduler::{self, Completion, JobGenerator, SchedulingResult, TenantBackgroundJobs},
+    scheduler::{
+        self, period_jitter, period_warmup, Completion, JobGenerator, SchedulingResult,
+        TenantBackgroundJobs,
+    },
     SecondaryTenant,
 };
 
@@ -41,11 +45,10 @@ use crate::tenant::{
 
 use camino::Utf8PathBuf;
 use chrono::format::{DelayedFormat, StrftimeItems};
-use futures::Future;
+use futures::{Future, StreamExt};
 use pageserver_api::models::SecondaryProgress;
 use pageserver_api::shard::TenantShardId;
-use rand::Rng;
-use remote_storage::{DownloadError, Etag, GenericRemoteStorage};
+use remote_storage::{DownloadError, Etag, GenericRemoteStorage, RemoteStorageActivity};
 
 use tokio_util::sync::CancellationToken;
 use tracing::{info_span, instrument, warn, Instrument};
@@ -68,20 +71,29 @@ use super::{
 /// `<ttps://github.com/neondatabase/neon/issues/6200>`
 const DOWNLOAD_FRESHEN_INTERVAL: Duration = Duration::from_millis(60000);
 
+/// Range of concurrency we may use when downloading layers within a timeline.  This is independent
+/// for each tenant we're downloading: the concurrency of _tenants_ is defined separately in
+/// `PageServerConf::secondary_download_concurrency`
+const MAX_LAYER_CONCURRENCY: usize = 16;
+const MIN_LAYER_CONCURRENCY: usize = 1;
+
 pub(super) async fn downloader_task(
     tenant_manager: Arc<TenantManager>,
     remote_storage: GenericRemoteStorage,
     command_queue: tokio::sync::mpsc::Receiver<CommandRequest<DownloadCommand>>,
     background_jobs_can_start: Barrier,
     cancel: CancellationToken,
+    root_ctx: RequestContext,
 ) {
-    let concurrency = tenant_manager.get_conf().secondary_download_concurrency;
+    // How many tenants' secondary download operations we will run concurrently
+    let tenant_concurrency = tenant_manager.get_conf().secondary_download_concurrency;
 
     let generator = SecondaryDownloader {
         tenant_manager,
         remote_storage,
+        root_ctx,
     };
-    let mut scheduler = Scheduler::new(generator, concurrency);
+    let mut scheduler = Scheduler::new(generator, tenant_concurrency);
 
     scheduler
         .run(command_queue, background_jobs_can_start, cancel)
@@ -92,12 +104,14 @@ pub(super) async fn downloader_task(
 struct SecondaryDownloader {
     tenant_manager: Arc<TenantManager>,
     remote_storage: GenericRemoteStorage,
+    root_ctx: RequestContext,
 }
 
 #[derive(Debug, Clone)]
 pub(super) struct OnDiskState {
     metadata: LayerFileMetadata,
     access_time: SystemTime,
+    local_path: Utf8PathBuf,
 }
 
 impl OnDiskState {
@@ -105,23 +119,37 @@ impl OnDiskState {
         _conf: &'static PageServerConf,
         _tenant_shard_id: &TenantShardId,
         _imeline_id: &TimelineId,
-        _ame: LayerFileName,
+        _ame: LayerName,
         metadata: LayerFileMetadata,
         access_time: SystemTime,
+        local_path: Utf8PathBuf,
     ) -> Self {
         Self {
             metadata,
             access_time,
+            local_path,
         }
     }
+
+    // This is infallible, because all errors are either acceptable (ENOENT), or totally
+    // unexpected (fatal).
+    pub(super) fn remove_blocking(&self) {
+        // We tolerate ENOENT, because between planning eviction and executing
+        // it, the secondary downloader could have seen an updated heatmap that
+        // resulted in a layer being deleted.
+        // Other local I/O errors are process-fatal: these should never happen.
+        std::fs::remove_file(&self.local_path)
+            .or_else(fs_ext::ignore_not_found)
+            .fatal_err("Deleting secondary layer")
+    }
 }
 
 #[derive(Debug, Clone, Default)]
 pub(super) struct SecondaryDetailTimeline {
-    pub(super) on_disk_layers: HashMap<LayerFileName, OnDiskState>,
+    pub(super) on_disk_layers: HashMap<LayerName, OnDiskState>,
 
     /// We remember when layers were evicted, to prevent re-downloading them.
-    pub(super) evicted_at: HashMap<LayerFileName, SystemTime>,
+    pub(super) evicted_at: HashMap<LayerName, SystemTime>,
 }
 
 /// This state is written by the secondary downloader, it is opaque
@@ -270,7 +298,7 @@ impl JobGenerator<PendingDownload, RunningDownload, CompleteDownload, DownloadCo
         // Update freshened_at even if there was an error: we don't want errored tenants to implicitly
         // take priority to run again.
         let mut detail = secondary_state.detail.lock().unwrap();
-        detail.next_download = Some(Instant::now() + DOWNLOAD_FRESHEN_INTERVAL);
+        detail.next_download = Some(Instant::now() + period_jitter(DOWNLOAD_FRESHEN_INTERVAL, 5));
     }
 
     async fn schedule(&mut self) -> SchedulingResult<PendingDownload> {
@@ -301,11 +329,9 @@ impl JobGenerator<PendingDownload, RunningDownload, CompleteDownload, DownloadCo
                     }
 
                     if detail.next_download.is_none() {
-                        // Initialize with a jitter: this spreads initial downloads on startup
-                        // or mass-attach across our freshen interval.
-                        let jittered_period =
-                            rand::thread_rng().gen_range(Duration::ZERO..DOWNLOAD_FRESHEN_INTERVAL);
-                        detail.next_download = Some(now.checked_add(jittered_period).expect(
+                        // Initialize randomly in the range from 0 to our interval: this uniformly spreads the start times.  Subsequent
+                        // rounds will use a smaller jitter to avoid accidentally synchronizing later.
+                        detail.next_download = Some(now.checked_add(period_warmup(DOWNLOAD_FRESHEN_INTERVAL)).expect(
                         "Using our constant, which is known to be small compared with clock range",
                     ));
                     }
@@ -367,11 +393,12 @@ impl JobGenerator<PendingDownload, RunningDownload, CompleteDownload, DownloadCo
         let remote_storage = self.remote_storage.clone();
         let conf = self.tenant_manager.get_conf();
         let tenant_shard_id = *secondary_state.get_tenant_shard_id();
+        let download_ctx = self.root_ctx.attached_child();
         (RunningDownload { barrier }, Box::pin(async move {
             let _completion = completion;
 
             match TenantDownloader::new(conf, &remote_storage, &secondary_state)
-                .download()
+                .download(&download_ctx)
                 .await
             {
                 Err(UpdateError::NoData) => {
@@ -485,7 +512,7 @@ impl<'a> TenantDownloader<'a> {
         }
     }
 
-    async fn download(&self) -> Result<(), UpdateError> {
+    async fn download(&self, ctx: &RequestContext) -> Result<(), UpdateError> {
         debug_assert_current_span_has_tenant_id();
 
         // For the duration of a download, we must hold the SecondaryTenant::gate, to ensure
@@ -560,7 +587,7 @@ impl<'a> TenantDownloader<'a> {
             }
 
             let timeline_id = timeline.timeline_id;
-            self.download_timeline(timeline)
+            self.download_timeline(timeline, ctx)
                 .instrument(tracing::info_span!(
                     "secondary_download_timeline",
                     tenant_id=%tenant_shard_id.tenant_id,
@@ -616,12 +643,12 @@ impl<'a> TenantDownloader<'a> {
                 let layers_in_heatmap = heatmap_timeline
                     .layers
                     .iter()
-                    .map(|l| &l.name)
+                    .map(|l| (&l.name, l.metadata.generation))
                     .collect::<HashSet<_>>();
                 let layers_on_disk = timeline_state
                     .on_disk_layers
                     .iter()
-                    .map(|l| l.0)
+                    .map(|l| (l.0, l.1.metadata.generation))
                     .collect::<HashSet<_>>();
 
                 let mut layer_count = layers_on_disk.len();
@@ -632,16 +659,24 @@ impl<'a> TenantDownloader<'a> {
                     .sum();
 
                 // Remove on-disk layers that are no longer present in heatmap
-                for layer in layers_on_disk.difference(&layers_in_heatmap) {
+                for (layer_file_name, generation) in layers_on_disk.difference(&layers_in_heatmap) {
                     layer_count -= 1;
                     layer_byte_count -= timeline_state
                         .on_disk_layers
-                        .get(layer)
+                        .get(layer_file_name)
                         .unwrap()
                         .metadata
                         .file_size();
 
-                    delete_layers.push((*timeline_id, (*layer).clone()));
+                    let local_path = local_layer_path(
+                        self.conf,
+                        self.secondary_state.get_tenant_shard_id(),
+                        timeline_id,
+                        layer_file_name,
+                        generation,
+                    );
+
+                    delete_layers.push((*timeline_id, (*layer_file_name).clone(), local_path));
                 }
 
                 progress.bytes_downloaded += layer_byte_count;
@@ -656,11 +691,7 @@ impl<'a> TenantDownloader<'a> {
         }
 
         // Execute accumulated deletions
-        for (timeline_id, layer_name) in delete_layers {
-            let timeline_path = self
-                .conf
-                .timeline_path(self.secondary_state.get_tenant_shard_id(), &timeline_id);
-            let local_path = timeline_path.join(layer_name.to_string());
+        for (timeline_id, layer_name, local_path) in delete_layers {
             tracing::info!(timeline_id=%timeline_id, "Removing secondary local layer {layer_name} because it's absent in heatmap",);
 
             tokio::fs::remove_file(&local_path)
@@ -742,12 +773,13 @@ impl<'a> TenantDownloader<'a> {
         .and_then(|x| x)
     }
 
-    async fn download_timeline(&self, timeline: HeatMapTimeline) -> Result<(), UpdateError> {
+    async fn download_timeline(
+        &self,
+        timeline: HeatMapTimeline,
+        ctx: &RequestContext,
+    ) -> Result<(), UpdateError> {
         debug_assert_current_span_has_tenant_and_timeline_id();
         let tenant_shard_id = self.secondary_state.get_tenant_shard_id();
-        let timeline_path = self
-            .conf
-            .timeline_path(tenant_shard_id, &timeline.timeline_id);
 
         // Accumulate updates to the state
         let mut touched = Vec::new();
@@ -782,6 +814,8 @@ impl<'a> TenantDownloader<'a> {
 
         tracing::debug!(timeline_id=%timeline.timeline_id, "Downloading layers, {} in heatmap", timeline.layers.len());
 
+        let mut download_futs = Vec::new();
+
         // Download heatmap layers that are not present on local disk, or update their
         // access time if they are already present.
         for layer in timeline.layers {
@@ -797,16 +831,12 @@ impl<'a> TenantDownloader<'a> {
                 if cfg!(debug_assertions) {
                     // Debug for https://github.com/neondatabase/neon/issues/6966: check that the files we think
                     // are already present on disk are really there.
-                    let local_path = self
-                        .conf
-                        .timeline_path(tenant_shard_id, &timeline.timeline_id)
-                        .join(layer.name.file_name());
-                    match tokio::fs::metadata(&local_path).await {
+                    match tokio::fs::metadata(&on_disk.local_path).await {
                         Ok(meta) => {
                             tracing::debug!(
                                 "Layer {} present at {}, size {}",
                                 layer.name,
-                                local_path,
+                                on_disk.local_path,
                                 meta.len(),
                             );
                         }
@@ -814,7 +844,7 @@ impl<'a> TenantDownloader<'a> {
                             tracing::warn!(
                                 "Layer {} not found at {} ({})",
                                 layer.name,
-                                local_path,
+                                on_disk.local_path,
                                 e
                             );
                             debug_assert!(false);
@@ -860,60 +890,33 @@ impl<'a> TenantDownloader<'a> {
                 }
             }
 
-            // Failpoint for simulating slow remote storage
-            failpoint_support::sleep_millis_async!(
-                "secondary-layer-download-sleep",
-                &self.secondary_state.cancel
-            );
+            download_futs.push(self.download_layer(
+                tenant_shard_id,
+                &timeline.timeline_id,
+                layer,
+                ctx,
+            ));
+        }
 
-            // Note: no backoff::retry wrapper here because download_layer_file does its own retries internally
-            let downloaded_bytes = match download_layer_file(
-                self.conf,
-                self.remote_storage,
-                *tenant_shard_id,
-                timeline.timeline_id,
-                &layer.name,
-                &LayerFileMetadata::from(&layer.metadata),
-                &self.secondary_state.cancel,
-            )
-            .await
-            {
-                Ok(bytes) => bytes,
-                Err(DownloadError::NotFound) => {
-                    // A heatmap might be out of date and refer to a layer that doesn't exist any more.
-                    // This is harmless: continue to download the next layer. It is expected during compaction
-                    // GC.
-                    tracing::debug!(
-                        "Skipped downloading missing layer {}, raced with compaction/gc?",
-                        layer.name
-                    );
-                    continue;
+        // Break up layer downloads into chunks, so that for each chunk we can re-check how much
+        // concurrency to use based on activity level of remote storage.
+        while !download_futs.is_empty() {
+            let chunk =
+                download_futs.split_off(download_futs.len().saturating_sub(MAX_LAYER_CONCURRENCY));
+
+            let concurrency = Self::layer_concurrency(self.remote_storage.activity());
+
+            let mut result_stream = futures::stream::iter(chunk).buffered(concurrency);
+            let mut result_stream = std::pin::pin!(result_stream);
+            while let Some(result) = result_stream.next().await {
+                match result {
+                    Err(e) => return Err(e),
+                    Ok(None) => {
+                        // No error, but we didn't download the layer.  Don't mark it touched
+                    }
+                    Ok(Some(layer)) => touched.push(layer),
                 }
-                Err(e) => return Err(e.into()),
-            };
-
-            if downloaded_bytes != layer.metadata.file_size {
-                let local_path = timeline_path.join(layer.name.to_string());
-
-                tracing::warn!(
-                    "Downloaded layer {} with unexpected size {} != {}.  Removing download.",
-                    layer.name,
-                    downloaded_bytes,
-                    layer.metadata.file_size
-                );
-
-                tokio::fs::remove_file(&local_path)
-                    .await
-                    .or_else(fs_ext::ignore_not_found)?;
-            } else {
-                tracing::info!("Downloaded layer {}, size {}", layer.name, downloaded_bytes);
-                let mut progress = self.secondary_state.progress.lock().unwrap();
-                progress.bytes_downloaded += downloaded_bytes;
-                progress.layers_downloaded += 1;
             }
-
-            SECONDARY_MODE.download_layer.inc();
-            touched.push(layer)
         }
 
         // Write updates to state to record layers we just downloaded or touched.
@@ -930,6 +933,13 @@ impl<'a> TenantDownloader<'a> {
                         v.get_mut().access_time = t.access_time;
                     }
                     Entry::Vacant(e) => {
+                        let local_path = local_layer_path(
+                            self.conf,
+                            tenant_shard_id,
+                            &timeline.timeline_id,
+                            &t.name,
+                            &t.metadata.generation,
+                        );
                         e.insert(OnDiskState::new(
                             self.conf,
                             tenant_shard_id,
@@ -937,6 +947,7 @@ impl<'a> TenantDownloader<'a> {
                             t.name,
                             LayerFileMetadata::from(&t.metadata),
                             t.access_time,
+                            local_path,
                         ));
                     }
                 }
@@ -945,6 +956,99 @@ impl<'a> TenantDownloader<'a> {
 
         Ok(())
     }
+
+    async fn download_layer(
+        &self,
+        tenant_shard_id: &TenantShardId,
+        timeline_id: &TimelineId,
+        layer: HeatMapLayer,
+        ctx: &RequestContext,
+    ) -> Result<Option<HeatMapLayer>, UpdateError> {
+        // Failpoint for simulating slow remote storage
+        failpoint_support::sleep_millis_async!(
+            "secondary-layer-download-sleep",
+            &self.secondary_state.cancel
+        );
+
+        let local_path = local_layer_path(
+            self.conf,
+            tenant_shard_id,
+            timeline_id,
+            &layer.name,
+            &layer.metadata.generation,
+        );
+
+        // Note: no backoff::retry wrapper here because download_layer_file does its own retries internally
+        let downloaded_bytes = match download_layer_file(
+            self.conf,
+            self.remote_storage,
+            *tenant_shard_id,
+            *timeline_id,
+            &layer.name,
+            &LayerFileMetadata::from(&layer.metadata),
+            &local_path,
+            &self.secondary_state.cancel,
+            ctx,
+        )
+        .await
+        {
+            Ok(bytes) => bytes,
+            Err(DownloadError::NotFound) => {
+                // A heatmap might be out of date and refer to a layer that doesn't exist any more.
+                // This is harmless: continue to download the next layer. It is expected during compaction
+                // GC.
+                tracing::debug!(
+                    "Skipped downloading missing layer {}, raced with compaction/gc?",
+                    layer.name
+                );
+                return Ok(None);
+            }
+            Err(e) => return Err(e.into()),
+        };
+
+        if downloaded_bytes != layer.metadata.file_size {
+            let local_path = local_layer_path(
+                self.conf,
+                tenant_shard_id,
+                timeline_id,
+                &layer.name,
+                &layer.metadata.generation,
+            );
+
+            tracing::warn!(
+                "Downloaded layer {} with unexpected size {} != {}.  Removing download.",
+                layer.name,
+                downloaded_bytes,
+                layer.metadata.file_size
+            );
+
+            tokio::fs::remove_file(&local_path)
+                .await
+                .or_else(fs_ext::ignore_not_found)?;
+        } else {
+            tracing::info!("Downloaded layer {}, size {}", layer.name, downloaded_bytes);
+            let mut progress = self.secondary_state.progress.lock().unwrap();
+            progress.bytes_downloaded += downloaded_bytes;
+            progress.layers_downloaded += 1;
+        }
+
+        SECONDARY_MODE.download_layer.inc();
+
+        Ok(Some(layer))
+    }
+
+    /// Calculate the currently allowed parallelism of layer download tasks, based on activity level of the remote storage
+    fn layer_concurrency(activity: RemoteStorageActivity) -> usize {
+        // When less than 75% of units are available, use minimum concurrency.  Else, do a linear mapping
+        // of our concurrency range to the units available within the remaining 25%.
+        let clamp_at = (activity.read_total * 3) / 4;
+        if activity.read_available > clamp_at {
+            (MAX_LAYER_CONCURRENCY * (activity.read_available - clamp_at))
+                / (activity.read_total - clamp_at)
+        } else {
+            MIN_LAYER_CONCURRENCY
+        }
+    }
 }
 
 /// Scan local storage and build up Layer objects based on the metadata in a HeatMapTimeline
@@ -976,7 +1080,7 @@ async fn init_timeline_state(
 
     // As we iterate through layers found on disk, we will look up their metadata from this map.
     // Layers not present in metadata will be discarded.
-    let heatmap_metadata: HashMap<&LayerFileName, &HeatMapLayer> =
+    let heatmap_metadata: HashMap<&LayerName, &HeatMapLayer> =
         heatmap.layers.iter().map(|l| (&l.name, l)).collect();
 
     while let Some(dentry) = dir
@@ -994,11 +1098,7 @@ async fn init_timeline_state(
             .fatal_err(&format!("Read metadata on {}", file_path));
 
         let file_name = file_path.file_name().expect("created it from the dentry");
-        if file_name == METADATA_FILE_NAME {
-            // Secondary mode doesn't use local metadata files, but they might have been left behind by an attached tenant.
-            warn!(path=?dentry.path(), "found legacy metadata file, these should have been removed in load_tenant_config");
-            continue;
-        } else if crate::is_temporary(&file_path)
+        if crate::is_temporary(&file_path)
             || is_temp_download_file(&file_path)
             || is_ephemeral_file(file_name)
         {
@@ -1013,7 +1113,7 @@ async fn init_timeline_state(
             continue;
         }
 
-        match LayerFileName::from_str(file_name) {
+        match LayerName::from_str(file_name) {
             Ok(name) => {
                 let remote_meta = heatmap_metadata.get(&name);
                 match remote_meta {
@@ -1040,6 +1140,7 @@ async fn init_timeline_state(
                                     name,
                                     LayerFileMetadata::from(&remote_meta.metadata),
                                     remote_meta.access_time,
+                                    file_path,
                                 ),
                             );
                         }
@@ -1071,3 +1172,58 @@ async fn init_timeline_state(
 
     detail
 }
+
+#[cfg(test)]
+mod test {
+    use super::*;
+
+    #[test]
+    fn layer_concurrency() {
+        // Totally idle
+        assert_eq!(
+            TenantDownloader::layer_concurrency(RemoteStorageActivity {
+                read_available: 16,
+                read_total: 16,
+                write_available: 16,
+                write_total: 16
+            }),
+            MAX_LAYER_CONCURRENCY
+        );
+
+        // Totally busy
+        assert_eq!(
+            TenantDownloader::layer_concurrency(RemoteStorageActivity {
+                read_available: 0,
+                read_total: 16,
+
+                write_available: 16,
+                write_total: 16
+            }),
+            MIN_LAYER_CONCURRENCY
+        );
+
+        // Edge of the range at which we interpolate
+        assert_eq!(
+            TenantDownloader::layer_concurrency(RemoteStorageActivity {
+                read_available: 12,
+                read_total: 16,
+
+                write_available: 16,
+                write_total: 16
+            }),
+            MIN_LAYER_CONCURRENCY
+        );
+
+        // Midpoint of the range in which we interpolate
+        assert_eq!(
+            TenantDownloader::layer_concurrency(RemoteStorageActivity {
+                read_available: 14,
+                read_total: 16,
+
+                write_available: 16,
+                write_total: 16
+            }),
+            MAX_LAYER_CONCURRENCY / 2
+        );
+    }
+}

pageserver/src/tenant/secondary/heatmap.rs

@@ -1,8 +1,6 @@
 use std::time::SystemTime;
 
-use crate::tenant::{
-    remote_timeline_client::index::IndexLayerMetadata, storage_layer::LayerFileName,
-};
+use crate::tenant::{remote_timeline_client::index::IndexLayerMetadata, storage_layer::LayerName};
 
 use serde::{Deserialize, Serialize};
 use serde_with::{serde_as, DisplayFromStr, TimestampSeconds};
@@ -17,6 +15,14 @@ pub(super) struct HeatMapTenant {
     pub(super) generation: Generation,
 
     pub(super) timelines: Vec<HeatMapTimeline>,
+
+    /// Uploaders provide their own upload period in the heatmap, as a hint to downloaders
+    /// of how frequently it is worthwhile to check for updates.
+    ///
+    /// This is optional for backward compat, and because we sometimes might upload
+    /// a heatmap explicitly via API for a tenant that has no periodic upload configured.
+    #[serde(default)]
+    pub(super) upload_period_ms: Option<u128>,
 }
 
 #[serde_as]
@@ -31,7 +37,7 @@ pub(crate) struct HeatMapTimeline {
 #[serde_as]
 #[derive(Serialize, Deserialize)]
 pub(crate) struct HeatMapLayer {
-    pub(super) name: LayerFileName,
+    pub(super) name: LayerName,
     pub(super) metadata: IndexLayerMetadata,
 
     #[serde_as(as = "TimestampSeconds<i64>")]
@@ -42,7 +48,7 @@ pub(crate) struct HeatMapLayer {
 
 impl HeatMapLayer {
     pub(crate) fn new(
-        name: LayerFileName,
+        name: LayerName,
         metadata: IndexLayerMetadata,
         access_time: SystemTime,
     ) -> Self {
@@ -83,4 +89,21 @@ impl HeatMapTenant {
 
         stats
     }
+
+    pub(crate) fn strip_atimes(self) -> Self {
+        Self {
+            timelines: self
+                .timelines
+                .into_iter()
+                .map(|mut tl| {
+                    for layer in &mut tl.layers {
+                        layer.access_time = SystemTime::UNIX_EPOCH;
+                    }
+                    tl
+                })
+                .collect(),
+            generation: self.generation,
+            upload_period_ms: self.upload_period_ms,
+        }
+    }
 }

pageserver/src/tenant/secondary/heatmap_uploader.rs

@@ -20,12 +20,14 @@ use crate::{
 
 use futures::Future;
 use pageserver_api::shard::TenantShardId;
-use rand::Rng;
 use remote_storage::{GenericRemoteStorage, TimeoutOrCancel};
 
 use super::{
     heatmap::HeatMapTenant,
-    scheduler::{self, JobGenerator, RunningJob, SchedulingResult, TenantBackgroundJobs},
+    scheduler::{
+        self, period_jitter, period_warmup, JobGenerator, RunningJob, SchedulingResult,
+        TenantBackgroundJobs,
+    },
     CommandRequest, UploadCommand,
 };
 use tokio_util::sync::CancellationToken;
@@ -78,7 +80,7 @@ impl RunningJob for WriteInProgress {
 
 struct UploadPending {
     tenant: Arc<Tenant>,
-    last_digest: Option<md5::Digest>,
+    last_upload: Option<LastUploadState>,
     target_time: Option<Instant>,
     period: Option<Duration>,
 }
@@ -92,7 +94,7 @@ impl scheduler::PendingJob for UploadPending {
 struct WriteComplete {
     tenant_shard_id: TenantShardId,
     completed_at: Instant,
-    digest: Option<md5::Digest>,
+    uploaded: Option<LastUploadState>,
     next_upload: Option<Instant>,
 }
 
@@ -113,10 +115,7 @@ struct UploaderTenantState {
     tenant: Weak<Tenant>,
 
     /// Digest of the serialized heatmap that we last successfully uploaded
-    ///
-    /// md5 is generally a bad hash.  We use it because it's convenient for interop with AWS S3's ETag,
-    /// which is also an md5sum.
-    last_digest: Option<md5::Digest>,
+    last_upload_state: Option<LastUploadState>,
 
     /// When the last upload attempt completed (may have been successful or failed)
     last_upload: Option<Instant>,
@@ -181,15 +180,11 @@ impl JobGenerator<UploadPending, WriteInProgress, WriteComplete, UploadCommand>
             let state = self
                 .tenants
                 .entry(*tenant.get_tenant_shard_id())
-                .or_insert_with(|| {
-                    let jittered_period = rand::thread_rng().gen_range(Duration::ZERO..period);
-
-                    UploaderTenantState {
-                        tenant: Arc::downgrade(&tenant),
-                        last_upload: None,
-                        next_upload: Some(now.checked_add(jittered_period).unwrap_or(now)),
-                        last_digest: None,
-                    }
+                .or_insert_with(|| UploaderTenantState {
+                    tenant: Arc::downgrade(&tenant),
+                    last_upload: None,
+                    next_upload: Some(now.checked_add(period_warmup(period)).unwrap_or(now)),
+                    last_upload_state: None,
                 });
 
             // Decline to do the upload if insufficient time has passed
@@ -197,10 +192,10 @@ impl JobGenerator<UploadPending, WriteInProgress, WriteComplete, UploadCommand>
                 return;
             }
 
-            let last_digest = state.last_digest;
+            let last_upload = state.last_upload_state.clone();
             result.jobs.push(UploadPending {
                 tenant,
-                last_digest,
+                last_upload,
                 target_time: state.next_upload,
                 period: Some(period),
             });
@@ -220,7 +215,7 @@ impl JobGenerator<UploadPending, WriteInProgress, WriteComplete, UploadCommand>
     ) {
         let UploadPending {
             tenant,
-            last_digest,
+            last_upload,
             target_time,
             period,
         } = job;
@@ -233,16 +228,16 @@ impl JobGenerator<UploadPending, WriteInProgress, WriteComplete, UploadCommand>
             let _completion = completion;
 
             let started_at = Instant::now();
-            let digest = match upload_tenant_heatmap(remote_storage, &tenant, last_digest).await {
-                Ok(UploadHeatmapOutcome::Uploaded(digest)) => {
+            let uploaded = match upload_tenant_heatmap(remote_storage, &tenant, last_upload.clone()).await {
+                Ok(UploadHeatmapOutcome::Uploaded(uploaded)) => {
                     let duration = Instant::now().duration_since(started_at);
                     SECONDARY_MODE
                         .upload_heatmap_duration
                         .observe(duration.as_secs_f64());
                     SECONDARY_MODE.upload_heatmap.inc();
-                    Some(digest)
+                    Some(uploaded)
                 }
-                Ok(UploadHeatmapOutcome::NoChange | UploadHeatmapOutcome::Skipped) => last_digest,
+                Ok(UploadHeatmapOutcome::NoChange | UploadHeatmapOutcome::Skipped) => last_upload,
                 Err(UploadHeatmapError::Upload(e)) => {
                     tracing::warn!(
                         "Failed to upload heatmap for tenant {}: {e:#}",
@@ -253,11 +248,11 @@ impl JobGenerator<UploadPending, WriteInProgress, WriteComplete, UploadCommand>
                         .upload_heatmap_duration
                         .observe(duration.as_secs_f64());
                     SECONDARY_MODE.upload_heatmap_errors.inc();
-                    last_digest
+                    last_upload
                 }
                 Err(UploadHeatmapError::Cancelled) => {
                     tracing::info!("Cancelled heatmap upload, shutting down");
-                    last_digest
+                    last_upload
                 }
             };
 
@@ -274,12 +269,12 @@ impl JobGenerator<UploadPending, WriteInProgress, WriteComplete, UploadCommand>
 
             let next_upload = tenant
                 .get_heatmap_period()
-                .and_then(|period| now.checked_add(period));
+                .and_then(|period| now.checked_add(period_jitter(period, 5)));
 
             WriteComplete {
                     tenant_shard_id: *tenant.get_tenant_shard_id(),
                     completed_at: now,
-                    digest,
+                    uploaded,
                     next_upload,
                 }
         }.instrument(info_span!(parent: None, "heatmap_upload", tenant_id=%tenant_shard_id.tenant_id, shard_id=%tenant_shard_id.shard_slug()))))
@@ -301,7 +296,7 @@ impl JobGenerator<UploadPending, WriteInProgress, WriteComplete, UploadCommand>
 
         Ok(UploadPending {
             // Ignore our state for last digest: this forces an upload even if nothing has changed
-            last_digest: None,
+            last_upload: None,
             tenant,
             target_time: None,
             period: None,
@@ -314,7 +309,7 @@ impl JobGenerator<UploadPending, WriteInProgress, WriteComplete, UploadCommand>
         let WriteComplete {
             tenant_shard_id,
             completed_at,
-            digest,
+            uploaded,
             next_upload,
         } = completion;
         use std::collections::hash_map::Entry;
@@ -324,7 +319,7 @@ impl JobGenerator<UploadPending, WriteInProgress, WriteComplete, UploadCommand>
             }
             Entry::Occupied(mut entry) => {
                 entry.get_mut().last_upload = Some(completed_at);
-                entry.get_mut().last_digest = digest;
+                entry.get_mut().last_upload_state = uploaded;
                 entry.get_mut().next_upload = next_upload
             }
         }
@@ -333,7 +328,7 @@ impl JobGenerator<UploadPending, WriteInProgress, WriteComplete, UploadCommand>
 
 enum UploadHeatmapOutcome {
     /// We successfully wrote to remote storage, with this digest.
-    Uploaded(md5::Digest),
+    Uploaded(LastUploadState),
     /// We did not upload because the heatmap digest was unchanged since the last upload
     NoChange,
     /// We skipped the upload for some reason, such as tenant/timeline not ready
@@ -349,12 +344,25 @@ enum UploadHeatmapError {
     Upload(#[from] anyhow::Error),
 }
 
+/// Digests describing the heatmap we most recently uploaded successfully.
+///
+/// md5 is generally a bad hash.  We use it because it's convenient for interop with AWS S3's ETag,
+/// which is also an md5sum.
+#[derive(Clone)]
+struct LastUploadState {
+    // Digest of json-encoded HeatMapTenant
+    uploaded_digest: md5::Digest,
+
+    // Digest without atimes set.
+    layers_only_digest: md5::Digest,
+}
+
 /// The inner upload operation.  This will skip if `last_digest` is Some and matches the digest
 /// of the object we would have uploaded.
 async fn upload_tenant_heatmap(
     remote_storage: GenericRemoteStorage,
     tenant: &Arc<Tenant>,
-    last_digest: Option<md5::Digest>,
+    last_upload: Option<LastUploadState>,
 ) -> Result<UploadHeatmapOutcome, UploadHeatmapError> {
     debug_assert_current_span_has_tenant_id();
 
@@ -370,6 +378,7 @@ async fn upload_tenant_heatmap(
     let mut heatmap = HeatMapTenant {
         timelines: Vec::new(),
         generation,
+        upload_period_ms: tenant.get_heatmap_period().map(|p| p.as_millis()),
     };
     let timelines = tenant.timelines.lock().unwrap().clone();
 
@@ -398,15 +407,31 @@ async fn upload_tenant_heatmap(
 
     // Serialize the heatmap
     let bytes = serde_json::to_vec(&heatmap).map_err(|e| anyhow::anyhow!(e))?;
-    let bytes = bytes::Bytes::from(bytes);
-    let size = bytes.len();
 
     // Drop out early if nothing changed since our last upload
     let digest = md5::compute(&bytes);
-    if Some(digest) == last_digest {
+    if Some(&digest) == last_upload.as_ref().map(|d| &d.uploaded_digest) {
         return Ok(UploadHeatmapOutcome::NoChange);
     }
 
+    // Calculate a digest that omits atimes, so that we can distinguish actual changes in
+    // layers from changes only in atimes.
+    let heatmap_size_bytes = heatmap.get_stats().bytes;
+    let layers_only_bytes =
+        serde_json::to_vec(&heatmap.strip_atimes()).map_err(|e| anyhow::anyhow!(e))?;
+    let layers_only_digest = md5::compute(&layers_only_bytes);
+    if heatmap_size_bytes < tenant.get_checkpoint_distance() {
+        // For small tenants, skip upload if only atimes changed. This avoids doing frequent
+        // uploads from long-idle tenants whose atimes are just incremented by periodic
+        // size calculations.
+        if Some(&layers_only_digest) == last_upload.as_ref().map(|d| &d.layers_only_digest) {
+            return Ok(UploadHeatmapOutcome::NoChange);
+        }
+    }
+
+    let bytes = bytes::Bytes::from(bytes);
+    let size = bytes.len();
+
     let path = remote_heatmap_path(tenant.get_tenant_shard_id());
 
     let cancel = &tenant.cancel;
@@ -438,5 +463,8 @@ async fn upload_tenant_heatmap(
 
     tracing::info!("Successfully uploaded {size} byte heatmap to {path}");
 
-    Ok(UploadHeatmapOutcome::Uploaded(digest))
+    Ok(UploadHeatmapOutcome::Uploaded(LastUploadState {
+        uploaded_digest: digest,
+        layers_only_digest,
+    }))
 }

pageserver/src/tenant/secondary/scheduler.rs

@@ -1,4 +1,5 @@
 use futures::Future;
+use rand::Rng;
 use std::{
     collections::HashMap,
     marker::PhantomData,
@@ -19,6 +20,26 @@ use super::{CommandRequest, CommandResponse};
 const MAX_SCHEDULING_INTERVAL: Duration = Duration::from_secs(10);
 const MIN_SCHEDULING_INTERVAL: Duration = Duration::from_secs(1);
 
+/// Jitter a Duration by an integer percentage.  Returned values are uniform
+/// in the range 100-pct..100+pct (i.e. a 5% jitter is 5% either way: a ~10% range)
+pub(super) fn period_jitter(d: Duration, pct: u32) -> Duration {
+    if d == Duration::ZERO {
+        d
+    } else {
+        rand::thread_rng().gen_range((d * (100 - pct)) / 100..(d * (100 + pct)) / 100)
+    }
+}
+
+/// When a periodic task first starts, it should wait for some time in the range 0..period, so
+/// that starting many such tasks at the same time spreads them across the time range.
+pub(super) fn period_warmup(period: Duration) -> Duration {
+    if period == Duration::ZERO {
+        period
+    } else {
+        rand::thread_rng().gen_range(Duration::ZERO..period)
+    }
+}
+
 /// Scheduling helper for background work across many tenants.
 ///
 /// Systems that need to run background work across many tenants may use this type

pageserver/src/tenant/size.rs

@@ -118,9 +118,6 @@ pub(super) async fn gather_inputs(
     ctx: &RequestContext,
 ) -> anyhow::Result<ModelInputs> {
     // refresh is needed to update gc related pitr_cutoff and horizon_cutoff
-    //
-    // FIXME: if a single timeline is deleted while refresh gc info is ongoing, we will fail the
-    // whole computation. It does not make sense from the billing perspective.
     tenant
         .refresh_gc_info(cancel, ctx)
         .await
@@ -192,7 +189,9 @@ pub(super) async fn gather_inputs(
         // than a space bound (horizon cutoff).  This means that if someone drops a database and waits for their
         // PITR interval, they will see synthetic size decrease, even if we are still storing data inside
         // horizon_cutoff.
-        let mut next_gc_cutoff = gc_info.pitr_cutoff;
+        let pitr_cutoff = gc_info.cutoffs.pitr;
+        let horizon_cutoff = gc_info.cutoffs.horizon;
+        let mut next_gc_cutoff = pitr_cutoff;
 
         // If the caller provided a shorter retention period, use that instead of the GC cutoff.
         let retention_param_cutoff = if let Some(max_retention_period) = max_retention_period {
@@ -219,6 +218,8 @@ pub(super) async fn gather_inputs(
             .map(|lsn| (lsn, LsnKind::BranchPoint))
             .collect::<Vec<_>>();
 
+        drop(gc_info);
+
         // Add branch points we collected earlier, just in case there were any that were
         // not present in retain_lsns. We will remove any duplicates below later.
         if let Some(this_branchpoints) = branchpoints.get(&timeline_id) {
@@ -297,8 +298,8 @@ pub(super) async fn gather_inputs(
             last_record: last_record_lsn,
             // this is not used above, because it might not have updated recently enough
             latest_gc_cutoff: *timeline.get_latest_gc_cutoff_lsn(),
-            horizon_cutoff: gc_info.horizon_cutoff,
-            pitr_cutoff: gc_info.pitr_cutoff,
+            horizon_cutoff,
+            pitr_cutoff,
             next_gc_cutoff,
             retention_param_cutoff,
         });

pageserver/src/tenant/storage_layer.rs

@@ -1,11 +1,11 @@
 //! Common traits and structs for layers
 
 pub mod delta_layer;
-mod filename;
 pub mod image_layer;
 pub(crate) mod inmemory_layer;
 pub(crate) mod layer;
 mod layer_desc;
+mod layer_name;
 
 use crate::context::{AccessStatsBehavior, RequestContext};
 use crate::repository::Value;
@@ -34,10 +34,10 @@ use utils::rate_limit::RateLimit;
 use utils::{id::TimelineId, lsn::Lsn};
 
 pub use delta_layer::{DeltaLayer, DeltaLayerWriter, ValueRef};
-pub use filename::{DeltaFileName, ImageFileName, LayerFileName};
 pub use image_layer::{ImageLayer, ImageLayerWriter};
 pub use inmemory_layer::InMemoryLayer;
 pub use layer_desc::{PersistentLayerDesc, PersistentLayerKey};
+pub use layer_name::{DeltaLayerName, ImageLayerName, LayerName};
 
 pub(crate) use layer::{EvictionError, Layer, ResidentLayer};
 
@@ -646,8 +646,8 @@ pub mod tests {
 
     use super::*;
 
-    impl From<DeltaFileName> for PersistentLayerDesc {
-        fn from(value: DeltaFileName) -> Self {
+    impl From<DeltaLayerName> for PersistentLayerDesc {
+        fn from(value: DeltaLayerName) -> Self {
             PersistentLayerDesc::new_delta(
                 TenantShardId::from([0; 18]),
                 TimelineId::from_array([0; 16]),
@@ -658,8 +658,8 @@ pub mod tests {
         }
     }
 
-    impl From<ImageFileName> for PersistentLayerDesc {
-        fn from(value: ImageFileName) -> Self {
+    impl From<ImageLayerName> for PersistentLayerDesc {
+        fn from(value: ImageLayerName) -> Self {
             PersistentLayerDesc::new_img(
                 TenantShardId::from([0; 18]),
                 TimelineId::from_array([0; 16]),
@@ -670,11 +670,11 @@ pub mod tests {
         }
     }
 
-    impl From<LayerFileName> for PersistentLayerDesc {
-        fn from(value: LayerFileName) -> Self {
+    impl From<LayerName> for PersistentLayerDesc {
+        fn from(value: LayerName) -> Self {
             match value {
-                LayerFileName::Delta(d) => Self::from(d),
-                LayerFileName::Image(i) => Self::from(i),
+                LayerName::Delta(d) => Self::from(d),
+                LayerName::Image(i) => Self::from(i),
             }
         }
     }