build(deps): bump certifi from 2023.7.22 to 2024.7.4 (#8301 )

Add concurrency to the find-large-objects scrubber subcommand (#8291 )
The find-large-objects scrubber subcommand is quite fast if you run it in an environment with low latency to the S3 bucket (say an EC2 instance in the same region). However, the higher the latency gets, the slower the command becomes. Therefore, add a concurrency param and make it parallelized. This doesn't change that general relationship, but at least lets us do multiple requests in parallel and therefore hopefully faster. Running with concurrency of 64 (default): ``` 2024-07-05T17:30:22.882959Z INFO lazy_load_identity [...] [...] 2024-07-05T17:30:28.289853Z INFO Scanned 500 shards. [...] ``` With concurrency of 1, simulating state before this PR: ``` 2024-07-05T17:31:43.375153Z INFO lazy_load_identity [...] [...] 2024-07-05T17:33:51.987092Z INFO Scanned 500 shards. [...] ``` In other words, to list 500 shards, speed is increased from 2:08 minutes to 6 seconds. Follow-up of #8257, part of #5431
2026-02-11 06:30:37 +00:00 · 2024-07-08 17:16:21 +01:00 · 2024-07-08 17:16:21 +01:00 · 2024-07-08 17:16:21 +01:00 · 2024-07-08 17:16:21 +01:00 · 2024-07-08 17:16:21 +01:00
234 changed files with 9439 additions and 4518 deletions
--- a/.github/actions/allure-report-generate/action.yml
+++ b/.github/actions/allure-report-generate/action.yml
@@ -183,7 +183,7 @@ runs:
      uses: actions/cache@v4
      with:
        path: ~/.cache/pypoetry/virtualenvs
-        key: v2-${{ runner.os }}-python-deps-${{ hashFiles('poetry.lock') }}
+        key: v2-${{ runner.os }}-${{ runner.arch }}-python-deps-${{ hashFiles('poetry.lock') }}

    - name: Store Allure test stat in the DB (new)
      if: ${{ !cancelled() && inputs.store-test-results-into-db == 'true' }}
--- a/.github/actions/download/action.yml
+++ b/.github/actions/download/action.yml
@@ -26,7 +26,7 @@ runs:
        TARGET: ${{ inputs.path }}
        ARCHIVE: /tmp/downloads/${{ inputs.name }}.tar.zst
        SKIP_IF_DOES_NOT_EXIST: ${{ inputs.skip-if-does-not-exist }}
-        PREFIX: artifacts/${{ inputs.prefix || format('{0}/{1}', github.run_id, github.run_attempt) }}
+        PREFIX: artifacts/${{ inputs.prefix || format('{0}/{1}/{2}', github.event.pull_request.head.sha || github.sha, github.run_id, github.run_attempt) }}
      run: |
        BUCKET=neon-github-public-dev
        FILENAME=$(basename $ARCHIVE)
--- a/.github/actions/run-python-test-set/action.yml
+++ b/.github/actions/run-python-test-set/action.yml
@@ -56,14 +56,14 @@ runs:
      if: inputs.build_type != 'remote'
      uses: ./.github/actions/download
      with:
-        name: neon-${{ runner.os }}-${{ inputs.build_type }}-artifact
+        name: neon-${{ runner.os }}-${{ runner.arch }}-${{ inputs.build_type }}-artifact
        path: /tmp/neon

    - name: Download Neon binaries for the previous release
      if: inputs.build_type != 'remote'
      uses: ./.github/actions/download
      with:
-        name: neon-${{ runner.os }}-${{ inputs.build_type }}-artifact
+        name: neon-${{ runner.os }}-${{ runner.arch }}-${{ inputs.build_type }}-artifact
        path: /tmp/neon-previous
        prefix: latest

@@ -89,7 +89,7 @@ runs:
      uses: actions/cache@v4
      with:
        path: ~/.cache/pypoetry/virtualenvs
-        key: v2-${{ runner.os }}-python-deps-${{ hashFiles('poetry.lock') }}
+        key: v2-${{ runner.os }}-${{ runner.arch }}-python-deps-${{ hashFiles('poetry.lock') }}

    - name: Install Python deps
      shell: bash -euxo pipefail {0}
@@ -114,6 +114,7 @@ runs:
        export PLATFORM=${PLATFORM:-github-actions-selfhosted}
        export POSTGRES_DISTRIB_DIR=${POSTGRES_DISTRIB_DIR:-/tmp/neon/pg_install}
        export DEFAULT_PG_VERSION=${PG_VERSION#v}
+        export LD_LIBRARY_PATH=${POSTGRES_DISTRIB_DIR}/v${DEFAULT_PG_VERSION}/lib

        if [ "${BUILD_TYPE}" = "remote" ]; then
          export REMOTE_ENV=1
@@ -178,7 +179,15 @@ runs:

        # Wake up the cluster if we use remote neon instance
        if [ "${{ inputs.build_type }}" = "remote" ] && [ -n "${BENCHMARK_CONNSTR}" ]; then
-          ${POSTGRES_DISTRIB_DIR}/v${DEFAULT_PG_VERSION}/bin/psql ${BENCHMARK_CONNSTR} -c "SELECT version();"
+          QUERIES=("SELECT version()")
+          if [[ "${PLATFORM}" = "neon"* ]]; then
+            QUERIES+=("SHOW neon.tenant_id")
+            QUERIES+=("SHOW neon.timeline_id")
+          fi
+
+          for q in "${QUERIES[@]}"; do
+            ${POSTGRES_DISTRIB_DIR}/v${DEFAULT_PG_VERSION}/bin/psql ${BENCHMARK_CONNSTR} -c "${q}"
+          done
        fi

        # Run the tests.
--- a/.github/actions/upload/action.yml
+++ b/.github/actions/upload/action.yml
@@ -8,7 +8,7 @@ inputs:
    description: "A directory or file to upload"
    required: true
  prefix:
-    description: "S3 prefix. Default is '${GITHUB_RUN_ID}/${GITHUB_RUN_ATTEMPT}'"
+    description: "S3 prefix. Default is '${GITHUB_SHA}/${GITHUB_RUN_ID}/${GITHUB_RUN_ATTEMPT}'"
    required: false

 runs:
@@ -45,7 +45,7 @@ runs:
      env:
        SOURCE: ${{ inputs.path }}
        ARCHIVE: /tmp/uploads/${{ inputs.name }}.tar.zst
-        PREFIX: artifacts/${{ inputs.prefix || format('{0}/{1}', github.run_id, github.run_attempt) }}
+        PREFIX: artifacts/${{ inputs.prefix || format('{0}/{1}/{2}', github.event.pull_request.head.sha || github.sha, github.run_id , github.run_attempt) }}
      run: |
        BUCKET=neon-github-public-dev
        FILENAME=$(basename $ARCHIVE)
--- a/.github/workflows/benchmarking.yml
+++ b/.github/workflows/benchmarking.yml
@@ -77,7 +77,7 @@ jobs:
    - name: Download Neon artifact
      uses: ./.github/actions/download
      with:
-        name: neon-${{ runner.os }}-release-artifact
+        name: neon-${{ runner.os }}-${{ runner.arch }}-release-artifact
        path: /tmp/neon/
        prefix: latest

@@ -235,15 +235,10 @@ jobs:
    - name: Download Neon artifact
      uses: ./.github/actions/download
      with:
-        name: neon-${{ runner.os }}-release-artifact
+        name: neon-${{ runner.os }}-${{ runner.arch }}-release-artifact
        path: /tmp/neon/
        prefix: latest

-    - name: Add Postgres binaries to PATH
-      run: |
-        ${POSTGRES_DISTRIB_DIR}/v${DEFAULT_PG_VERSION}/bin/pgbench --version
-        echo "${POSTGRES_DISTRIB_DIR}/v${DEFAULT_PG_VERSION}/bin" >> $GITHUB_PATH
-
    - name: Create Neon Project
      if: contains(fromJson('["neon-captest-new", "neon-captest-freetier", "neonvm-captest-new", "neonvm-captest-freetier"]'), matrix.platform)
      id: create-neon-project
@@ -282,16 +277,6 @@ jobs:

        echo "connstr=${CONNSTR}" >> $GITHUB_OUTPUT

-        QUERIES=("SELECT version()")
-        if [[ "${PLATFORM}" = "neon"* ]]; then
-          QUERIES+=("SHOW neon.tenant_id")
-          QUERIES+=("SHOW neon.timeline_id")
-        fi
-
-        for q in "${QUERIES[@]}"; do
-          psql ${CONNSTR} -c "${q}"
-        done
-
    - name: Benchmark init
      uses: ./.github/actions/run-python-test-set
      with:
@@ -373,29 +358,16 @@ jobs:
    - name: Download Neon artifact
      uses: ./.github/actions/download
      with:
-        name: neon-${{ runner.os }}-release-artifact
+        name: neon-${{ runner.os }}-${{ runner.arch }}-release-artifact
        path: /tmp/neon/
        prefix: latest

-    - name: Add Postgres binaries to PATH
-      run: |
-        ${POSTGRES_DISTRIB_DIR}/v${DEFAULT_PG_VERSION}/bin/pgbench --version
-        echo "${POSTGRES_DISTRIB_DIR}/v${DEFAULT_PG_VERSION}/bin" >> $GITHUB_PATH
-
    - name: Set up Connection String
      id: set-up-connstr
      run: |
        CONNSTR=${{ secrets.BENCHMARK_PGVECTOR_CONNSTR }}
-        
-        echo "connstr=${CONNSTR}" >> $GITHUB_OUTPUT

-        QUERIES=("SELECT version()")
-        QUERIES+=("SHOW neon.tenant_id")
-        QUERIES+=("SHOW neon.timeline_id")
-        
-        for q in "${QUERIES[@]}"; do
-          psql ${CONNSTR} -c "${q}"
-        done
+        echo "connstr=${CONNSTR}" >> $GITHUB_OUTPUT

    - name: Benchmark pgvector hnsw indexing
      uses: ./.github/actions/run-python-test-set
@@ -417,12 +389,12 @@ jobs:
        test_selection: performance/test_perf_pgvector_queries.py
        run_in_parallel: false
        save_perf_report: ${{ env.SAVE_PERF_REPORT }}
-        extra_params: -m remote_cluster --timeout 21600 
+        extra_params: -m remote_cluster --timeout 21600
      env:
        BENCHMARK_CONNSTR: ${{ steps.set-up-connstr.outputs.connstr }}
        VIP_VAP_ACCESS_TOKEN: "${{ secrets.VIP_VAP_ACCESS_TOKEN }}"
        PERF_TEST_RESULT_CONNSTR: "${{ secrets.PERF_TEST_RESULT_CONNSTR }}"
-    
+
    - name: Create Allure report
      if: ${{ !cancelled() }}
      uses: ./.github/actions/allure-report-generate
@@ -473,15 +445,10 @@ jobs:
    - name: Download Neon artifact
      uses: ./.github/actions/download
      with:
-        name: neon-${{ runner.os }}-release-artifact
+        name: neon-${{ runner.os }}-${{ runner.arch }}-release-artifact
        path: /tmp/neon/
        prefix: latest

-    - name: Add Postgres binaries to PATH
-      run: |
-        ${POSTGRES_DISTRIB_DIR}/v${DEFAULT_PG_VERSION}/bin/pgbench --version
-        echo "${POSTGRES_DISTRIB_DIR}/v${DEFAULT_PG_VERSION}/bin" >> $GITHUB_PATH
-
    - name: Set up Connection String
      id: set-up-connstr
      run: |
@@ -503,16 +470,6 @@ jobs:

        echo "connstr=${CONNSTR}" >> $GITHUB_OUTPUT

-        QUERIES=("SELECT version()")
-        if [[ "${PLATFORM}" = "neon"* ]]; then
-          QUERIES+=("SHOW neon.tenant_id")
-          QUERIES+=("SHOW neon.timeline_id")
-        fi
-
-        for q in "${QUERIES[@]}"; do
-          psql ${CONNSTR} -c "${q}"
-        done
-
    - name: ClickBench benchmark
      uses: ./.github/actions/run-python-test-set
      with:
@@ -576,15 +533,10 @@ jobs:
    - name: Download Neon artifact
      uses: ./.github/actions/download
      with:
-        name: neon-${{ runner.os }}-release-artifact
+        name: neon-${{ runner.os }}-${{ runner.arch }}-release-artifact
        path: /tmp/neon/
        prefix: latest

-    - name: Add Postgres binaries to PATH
-      run: |
-        ${POSTGRES_DISTRIB_DIR}/v${DEFAULT_PG_VERSION}/bin/pgbench --version
-        echo "${POSTGRES_DISTRIB_DIR}/v${DEFAULT_PG_VERSION}/bin" >> $GITHUB_PATH
-
    - name: Get Connstring Secret Name
      run: |
        case "${PLATFORM}" in
@@ -613,16 +565,6 @@ jobs:

        echo "connstr=${CONNSTR}" >> $GITHUB_OUTPUT

-        QUERIES=("SELECT version()")
-        if [[ "${PLATFORM}" = "neon"* ]]; then
-          QUERIES+=("SHOW neon.tenant_id")
-          QUERIES+=("SHOW neon.timeline_id")
-        fi
-
-        for q in "${QUERIES[@]}"; do
-          psql ${CONNSTR} -c "${q}"
-        done
-
    - name: Run TPC-H benchmark
      uses: ./.github/actions/run-python-test-set
      with:
@@ -677,15 +619,10 @@ jobs:
    - name: Download Neon artifact
      uses: ./.github/actions/download
      with:
-        name: neon-${{ runner.os }}-release-artifact
+        name: neon-${{ runner.os }}-${{ runner.arch }}-release-artifact
        path: /tmp/neon/
        prefix: latest

-    - name: Add Postgres binaries to PATH
-      run: |
-        ${POSTGRES_DISTRIB_DIR}/v${DEFAULT_PG_VERSION}/bin/pgbench --version
-        echo "${POSTGRES_DISTRIB_DIR}/v${DEFAULT_PG_VERSION}/bin" >> $GITHUB_PATH
-
    - name: Set up Connection String
      id: set-up-connstr
      run: |
@@ -707,16 +644,6 @@ jobs:

        echo "connstr=${CONNSTR}" >> $GITHUB_OUTPUT

-        QUERIES=("SELECT version()")
-        if [[ "${PLATFORM}" = "neon"* ]]; then
-          QUERIES+=("SHOW neon.tenant_id")
-          QUERIES+=("SHOW neon.timeline_id")
-        fi
-
-        for q in "${QUERIES[@]}"; do
-          psql ${CONNSTR} -c "${q}"
-        done
-
    - name: Run user examples
      uses: ./.github/actions/run-python-test-set
      with:
--- a/.github/workflows/build-build-tools-image.yml
+++ b/.github/workflows/build-build-tools-image.yml
@@ -63,14 +63,16 @@ jobs:
          mkdir -p /tmp/.docker-custom
          echo DOCKER_CONFIG=/tmp/.docker-custom >> $GITHUB_ENV

-      - uses: docker/setup-buildx-action@v2
+      - uses: docker/setup-buildx-action@v3
+        with:
+          cache-binary: false

-      - uses: docker/login-action@v2
+      - uses: docker/login-action@v3
        with:
          username: ${{ secrets.NEON_DOCKERHUB_USERNAME }}
          password: ${{ secrets.NEON_DOCKERHUB_PASSWORD }}

-      - uses: docker/build-push-action@v4
+      - uses: docker/build-push-action@v6
        with:
          context: .
          provenance: false
@@ -78,10 +80,11 @@ jobs:
          pull: true
          file: Dockerfile.build-tools
          cache-from: type=registry,ref=neondatabase/build-tools:cache-${{ matrix.arch }}
-          cache-to: type=registry,ref=neondatabase/build-tools:cache-${{ matrix.arch }},mode=max
+          cache-to: ${{ github.ref_name == 'main' && format('type=registry,ref=neondatabase/build-tools:cache-{0},mode=max', matrix.arch) || '' }}
          tags: neondatabase/build-tools:${{ inputs.image-tag }}-${{ matrix.arch }}

      - name: Remove custom docker config directory
+        if: always()
        run: |
          rm -rf /tmp/.docker-custom

--- a/.github/workflows/build_and_test.yml
+++ b/.github/workflows/build_and_test.yml
@@ -30,7 +30,7 @@ jobs:
    if: ${{ !contains(github.event.pull_request.labels.*.name, 'run-no-ci') }}
    uses: ./.github/workflows/check-permissions.yml
    with:
-      github-event-name: ${{ github.event_name}}
+      github-event-name: ${{ github.event_name }}

  cancel-previous-e2e-tests:
    needs: [ check-permissions ]
@@ -109,7 +109,7 @@ jobs:
        uses: actions/cache@v4
        with:
          path: ~/.cache/pypoetry/virtualenvs
-          key: v2-${{ runner.os }}-python-deps-${{ hashFiles('poetry.lock') }}
+          key: v2-${{ runner.os }}-${{ runner.arch }}-python-deps-${{ hashFiles('poetry.lock') }}

      - name: Install Python deps
        run: ./scripts/pysync
@@ -149,7 +149,7 @@ jobs:
 #            !~/.cargo/registry/src
 #            ~/.cargo/git/
 #            target/
-#          key: v1-${{ runner.os }}-cargo-clippy-${{ hashFiles('rust-toolchain.toml') }}-${{ hashFiles('Cargo.lock') }}
+#          key: v1-${{ runner.os }}-${{ runner.arch }}-cargo-clippy-${{ hashFiles('rust-toolchain.toml') }}-${{ hashFiles('Cargo.lock') }}

      # Some of our rust modules use FFI and need those to be checked
      - name: Get postgres headers
@@ -291,29 +291,29 @@ jobs:
 #            target/
 #          # Fall back to older versions of the key, if no cache for current Cargo.lock was found
 #          key: |
-#            v1-${{ runner.os }}-${{ matrix.build_type }}-cargo-${{ hashFiles('rust-toolchain.toml') }}-${{ hashFiles('Cargo.lock') }}
-#            v1-${{ runner.os }}-${{ matrix.build_type }}-cargo-${{ hashFiles('rust-toolchain.toml') }}-
+#            v1-${{ runner.os }}-${{ runner.arch }}-${{ matrix.build_type }}-cargo-${{ hashFiles('rust-toolchain.toml') }}-${{ hashFiles('Cargo.lock') }}
+#            v1-${{ runner.os }}-${{ runner.arch }}-${{ matrix.build_type }}-cargo-${{ hashFiles('rust-toolchain.toml') }}-

      - name: Cache postgres v14 build
        id: cache_pg_14
        uses: actions/cache@v4
        with:
          path: pg_install/v14
-          key: v1-${{ runner.os }}-${{ matrix.build_type }}-pg-${{ steps.pg_v14_rev.outputs.pg_rev }}-${{ hashFiles('Makefile', 'Dockerfile.build-tools') }}
+          key: v1-${{ runner.os }}-${{ runner.arch }}-${{ matrix.build_type }}-pg-${{ steps.pg_v14_rev.outputs.pg_rev }}-${{ hashFiles('Makefile', 'Dockerfile.build-tools') }}

      - name: Cache postgres v15 build
        id: cache_pg_15
        uses: actions/cache@v4
        with:
          path: pg_install/v15
-          key: v1-${{ runner.os }}-${{ matrix.build_type }}-pg-${{ steps.pg_v15_rev.outputs.pg_rev }}-${{ hashFiles('Makefile', 'Dockerfile.build-tools') }}
+          key: v1-${{ runner.os }}-${{ runner.arch }}-${{ matrix.build_type }}-pg-${{ steps.pg_v15_rev.outputs.pg_rev }}-${{ hashFiles('Makefile', 'Dockerfile.build-tools') }}

      - name: Cache postgres v16 build
        id: cache_pg_16
        uses: actions/cache@v4
        with:
          path: pg_install/v16
-          key: v1-${{ runner.os }}-${{ matrix.build_type }}-pg-${{ steps.pg_v16_rev.outputs.pg_rev }}-${{ hashFiles('Makefile', 'Dockerfile.build-tools') }}
+          key: v1-${{ runner.os }}-${{ runner.arch }}-${{ matrix.build_type }}-pg-${{ steps.pg_v16_rev.outputs.pg_rev }}-${{ hashFiles('Makefile', 'Dockerfile.build-tools') }}

      - name: Build postgres v14
        if: steps.cache_pg_14.outputs.cache-hit != 'true'
@@ -335,6 +335,8 @@ jobs:

      - name: Run cargo build
        run: |
+          PQ_LIB_DIR=$(pwd)/pg_install/v16/lib
+          export PQ_LIB_DIR
          ${cov_prefix} mold -run cargo build $CARGO_FLAGS $CARGO_FEATURES --bins --tests

      # Do install *before* running rust tests because they might recompile the
@@ -383,6 +385,11 @@ jobs:
        env:
          NEXTEST_RETRIES: 3
        run: |
+          PQ_LIB_DIR=$(pwd)/pg_install/v16/lib
+          export PQ_LIB_DIR
+          LD_LIBRARY_PATH=$(pwd)/pg_install/v16/lib
+          export LD_LIBRARY_PATH
+
          #nextest does not yet support running doctests
          cargo test --doc $CARGO_FLAGS $CARGO_FEATURES

@@ -411,7 +418,7 @@ jobs:
      - name: Upload Neon artifact
        uses: ./.github/actions/upload
        with:
-          name: neon-${{ runner.os }}-${{ matrix.build_type }}-artifact
+          name: neon-${{ runner.os }}-${{ runner.arch }}-${{ matrix.build_type }}-artifact
          path: /tmp/neon

      # XXX: keep this after the binaries.list is formed, so the coverage can properly work later
@@ -490,7 +497,7 @@ jobs:
        uses: actions/cache@v4
        with:
          path: ~/.cache/pypoetry/virtualenvs
-          key: v1-${{ runner.os }}-python-deps-${{ hashFiles('poetry.lock') }}
+          key: v1-${{ runner.os }}-${{ runner.arch }}-python-deps-${{ hashFiles('poetry.lock') }}

      - name: Install Python deps
        run: ./scripts/pysync
@@ -639,7 +646,7 @@ jobs:
      - name: Get Neon artifact
        uses: ./.github/actions/download
        with:
-          name: neon-${{ runner.os }}-${{ matrix.build_type }}-artifact
+          name: neon-${{ runner.os }}-${{ runner.arch }}-${{ matrix.build_type }}-artifact
          path: /tmp/neon

      - name: Get coverage artifact
@@ -744,14 +751,16 @@ jobs:
        run: |
          mkdir -p .docker-custom
          echo DOCKER_CONFIG=$(pwd)/.docker-custom >> $GITHUB_ENV
-      - uses: docker/setup-buildx-action@v2
+      - uses: docker/setup-buildx-action@v3
+        with:
+          cache-binary: false

      - uses: docker/login-action@v3
        with:
          username: ${{ secrets.NEON_DOCKERHUB_USERNAME }}
          password: ${{ secrets.NEON_DOCKERHUB_PASSWORD }}

-      - uses: docker/build-push-action@v5
+      - uses: docker/build-push-action@v6
        with:
          context: .
          build-args: |
@@ -763,7 +772,7 @@ jobs:
          pull: true
          file: Dockerfile
          cache-from: type=registry,ref=neondatabase/neon:cache-${{ matrix.arch }}
-          cache-to: type=registry,ref=neondatabase/neon:cache-${{ matrix.arch }},mode=max
+          cache-to: ${{ github.ref_name == 'main' && format('type=registry,ref=neondatabase/neon:cache-{0},mode=max', matrix.arch) || '' }}
          tags: |
            neondatabase/neon:${{ needs.tag.outputs.build-tag }}-${{ matrix.arch }}

@@ -822,11 +831,12 @@ jobs:
        run: |
          mkdir -p .docker-custom
          echo DOCKER_CONFIG=$(pwd)/.docker-custom >> $GITHUB_ENV
-      - uses: docker/setup-buildx-action@v2
+      - uses: docker/setup-buildx-action@v3
        with:
+          cache-binary: false
          # Disable parallelism for docker buildkit.
          # As we already build everything with `make -j$(nproc)`, running it in additional level of parallelisam blows up the Runner.
-          config-inline: |
+          buildkitd-config-inline: |
            [worker.oci]
              max-parallelism = 1

@@ -842,7 +852,7 @@ jobs:
          password: ${{ secrets.AWS_SECRET_KEY_DEV }}

      - name: Build compute-node image
-        uses: docker/build-push-action@v5
+        uses: docker/build-push-action@v6
        with:
          context: .
          build-args: |
@@ -855,13 +865,13 @@ jobs:
          pull: true
          file: Dockerfile.compute-node
          cache-from: type=registry,ref=neondatabase/compute-node-${{ matrix.version }}:cache-${{ matrix.arch }}
-          cache-to: type=registry,ref=neondatabase/compute-node-${{ matrix.version }}:cache-${{ matrix.arch }},mode=max
+          cache-to: ${{ github.ref_name == 'main' && format('type=registry,ref=neondatabase/compute-node-{0}:cache-{1},mode=max', matrix.version, matrix.arch) || '' }}
          tags: |
            neondatabase/compute-node-${{ matrix.version }}:${{ needs.tag.outputs.build-tag }}-${{ matrix.arch }}

      - name: Build neon extensions test image
        if: matrix.version == 'v16'
-        uses: docker/build-push-action@v5
+        uses: docker/build-push-action@v6
        with:
          context: .
          build-args: |
@@ -875,14 +885,14 @@ jobs:
          file: Dockerfile.compute-node
          target: neon-pg-ext-test
          cache-from: type=registry,ref=neondatabase/neon-test-extensions-${{ matrix.version }}:cache-${{ matrix.arch }}
-          cache-to: type=registry,ref=neondatabase/neon-test-extensions-${{ matrix.version }}:cache-${{ matrix.arch }},mode=max
+          cache-to: ${{ github.ref_name == 'main' && format('type=registry,ref=neondatabase/neon-test-extensions-{0}:cache-{1},mode=max', matrix.version, matrix.arch) || '' }}
          tags: |
            neondatabase/neon-test-extensions-${{ matrix.version }}:${{needs.tag.outputs.build-tag}}-${{ matrix.arch }}

      - name: Build compute-tools image
        # compute-tools are Postgres independent, so build it only once
        if: matrix.version == 'v16'
-        uses: docker/build-push-action@v5
+        uses: docker/build-push-action@v6
        with:
          target: compute-tools-image
          context: .
@@ -1245,6 +1255,7 @@ jobs:
        run: |
          if [[ "$GITHUB_REF_NAME" == "main" ]]; then
            gh workflow --repo neondatabase/aws run deploy-dev.yml --ref main -f branch=main -f dockerTag=${{needs.tag.outputs.build-tag}} -f deployPreprodRegion=false
+            gh workflow --repo neondatabase/azure run deploy.yml -f dockerTag=${{needs.tag.outputs.build-tag}}
          elif [[ "$GITHUB_REF_NAME" == "release" ]]; then
            gh workflow --repo neondatabase/aws run deploy-dev.yml --ref main \
              -f deployPgSniRouter=false \
@@ -1339,7 +1350,7 @@ jobs:
          # Update Neon artifact for the release (reuse already uploaded artifact)
          for build_type in debug release; do
            OLD_PREFIX=artifacts/${GITHUB_RUN_ID}
-            FILENAME=neon-${{ runner.os }}-${build_type}-artifact.tar.zst
+            FILENAME=neon-${{ runner.os }}-${{ runner.arch }}-${build_type}-artifact.tar.zst

            S3_KEY=$(aws s3api list-objects-v2 --bucket ${BUCKET} --prefix ${OLD_PREFIX} | jq -r '.Contents[]?.Key' | grep ${FILENAME} | sort --version-sort | tail -1 || true)
            if [ -z "${S3_KEY}" ]; then
@@ -1357,3 +1368,31 @@ jobs:
    with:
      from-tag: ${{ needs.build-build-tools-image.outputs.image-tag }}
    secrets: inherit
+
+  # This job simplifies setting branch protection rules (in GitHub UI)
+  # by allowing to set only this job instead of listing many others.
+  # It also makes it easier to rename or parametrise jobs (using matrix)
+  # which requires changes in branch protection rules
+  #
+  # Note, that we can't add external check (like `neon-cloud-e2e`) we still need to use GitHub UI for that.
+  #
+  # https://github.com/neondatabase/neon/settings/branch_protection_rules
+  conclusion:
+    if: always()
+    # Format `needs` differently to make the list more readable.
+    # Usually we do `needs: [...]`
+    needs:
+      - check-codestyle-python
+      - check-codestyle-rust
+      - regress-tests
+      - test-images
+    runs-on: ubuntu-22.04
+    steps:
+      # The list of possible results:
+      # https://docs.github.com/en/actions/learn-github-actions/contexts#needs-context
+      - name: Fail the job if any of the dependencies do not succeed
+        run: exit 1
+        if: |
+          contains(needs.*.result, 'failure')
+          || contains(needs.*.result, 'cancelled')
+          || contains(needs.*.result, 'skipped')
--- a/.github/workflows/neon_extra_builds.yml
+++ b/.github/workflows/neon_extra_builds.yml
@@ -232,12 +232,19 @@ jobs:

      - name: Run cargo build
        run: |
+          PQ_LIB_DIR=$(pwd)/pg_install/v16/lib
+          export PQ_LIB_DIR
          mold -run cargo build --locked $CARGO_FLAGS $CARGO_FEATURES --bins --tests -j$(nproc)

      - name: Run cargo test
        env:
          NEXTEST_RETRIES: 3
        run: |
+          PQ_LIB_DIR=$(pwd)/pg_install/v16/lib
+          export PQ_LIB_DIR
+          LD_LIBRARY_PATH=$(pwd)/pg_install/v16/lib
+          export LD_LIBRARY_PATH
+
          cargo nextest run $CARGO_FEATURES -j$(nproc)

          # Run separate tests for real S3
@@ -378,7 +385,7 @@ jobs:
        run: make walproposer-lib -j$(nproc)

      - name: Produce the build stats
-        run: cargo build --all --release --timings -j$(nproc)
+        run: PQ_LIB_DIR=$(pwd)/pg_install/v16/lib cargo build --all --release --timings -j$(nproc)

      - name: Upload the build stats
        id: upload-stats
--- a/.github/workflows/periodic_pagebench.yml
+++ b/.github/workflows/periodic_pagebench.yml
@@ -0,0 +1,155 @@
+name: Periodic pagebench performance test on dedicated EC2 machine in eu-central-1 region
+
+on:
+  schedule:
+    # * is a special character in YAML so you have to quote this string
+    #          ┌───────────── minute (0 - 59)
+    #          │ ┌───────────── hour (0 - 23)
+    #          │ │ ┌───────────── day of the month (1 - 31)
+    #          │ │ │ ┌───────────── month (1 - 12 or JAN-DEC)
+    #          │ │ │ │ ┌───────────── day of the week (0 - 6 or SUN-SAT)
+    - cron:  '0 18 * * *' # Runs at 6 PM UTC every day
+  workflow_dispatch: # Allows manual triggering of the workflow
+    inputs:
+      commit_hash:
+        type: string
+        description: 'The long neon repo commit hash for the system under test (pageserver) to be tested.'
+        required: false
+        default: ''
+
+defaults:
+  run:
+    shell: bash -euo pipefail {0}
+
+concurrency:
+  group: ${{ github.workflow }}
+  cancel-in-progress: false
+
+jobs:
+  trigger_bench_on_ec2_machine_in_eu_central_1:
+    runs-on: [ self-hosted, gen3, small ]
+    container:
+      image: neondatabase/build-tools:pinned
+      credentials:
+        username: ${{ secrets.NEON_DOCKERHUB_USERNAME }}
+        password: ${{ secrets.NEON_DOCKERHUB_PASSWORD }}
+      options: --init
+    timeout-minutes: 360  # Set the timeout to 6 hours
+    env:
+      API_KEY: ${{ secrets.PERIODIC_PAGEBENCH_EC2_RUNNER_API_KEY }}
+      RUN_ID: ${{ github.run_id }}
+      AWS_ACCESS_KEY_ID: ${{ secrets.AWS_EC2_US_TEST_RUNNER_ACCESS_KEY_ID }}
+      AWS_SECRET_ACCESS_KEY : ${{ secrets.AWS_EC2_US_TEST_RUNNER_ACCESS_KEY_SECRET }}
+      AWS_DEFAULT_REGION : "eu-central-1"
+      AWS_INSTANCE_ID : "i-02a59a3bf86bc7e74"
+    steps:
+    # we don't need the neon source code because we run everything remotely
+    # however we still need the local github actions to run the allure step below
+    - uses: actions/checkout@v4
+
+    - name: Show my own (github runner) external IP address - usefull for IP allowlisting
+      run: curl https://ifconfig.me
+
+    - name: Start EC2 instance and wait for the instance to boot up
+      run: |
+        aws ec2 start-instances --instance-ids $AWS_INSTANCE_ID
+        aws ec2 wait instance-running --instance-ids $AWS_INSTANCE_ID
+        sleep 60 # sleep some time to allow cloudinit and our API server to start up
+
+    - name: Determine public IP of the EC2 instance and set env variable EC2_MACHINE_URL_US
+      run: |
+        public_ip=$(aws ec2 describe-instances --instance-ids $AWS_INSTANCE_ID --query 'Reservations[*].Instances[*].PublicIpAddress' --output text)
+        echo "Public IP of the EC2 instance: $public_ip"
+        echo "EC2_MACHINE_URL_US=https://${public_ip}:8443" >> $GITHUB_ENV
+
+    - name: Determine commit hash
+      env:
+        INPUT_COMMIT_HASH: ${{ github.event.inputs.commit_hash }}
+      run: |
+        if [ -z "$INPUT_COMMIT_HASH" ]; then
+          echo "COMMIT_HASH=$(curl -s https://api.github.com/repos/neondatabase/neon/commits/main | jq -r '.sha')" >> $GITHUB_ENV
+        else
+          echo "COMMIT_HASH=$INPUT_COMMIT_HASH" >> $GITHUB_ENV
+        fi
+
+    - name: Start Bench with run_id   
+      run: |
+        curl -k -X 'POST' \
+        "${EC2_MACHINE_URL_US}/start_test/${GITHUB_RUN_ID}" \
+        -H 'accept: application/json' \
+        -H 'Content-Type: application/json' \
+        -H "Authorization: Bearer $API_KEY" \
+        -d "{\"neonRepoCommitHash\": \"${COMMIT_HASH}\"}"
+
+    - name: Poll Test Status
+      id: poll_step
+      run: |
+        status=""
+        while [[ "$status" != "failure" && "$status" != "success" ]]; do
+          response=$(curl -k -X 'GET' \
+          "${EC2_MACHINE_URL_US}/test_status/${GITHUB_RUN_ID}" \
+          -H 'accept: application/json' \
+          -H "Authorization: Bearer $API_KEY")
+          echo "Response: $response"
+          set +x
+          status=$(echo $response | jq -r '.status')
+          echo "Test status: $status"
+          if [[ "$status" == "failure" ]]; then
+            echo "Test failed"
+            exit 1 # Fail the job step if status is failure
+          elif [[ "$status" == "success" || "$status" == "null" ]]; then
+            break
+          elif [[ "$status" == "too_many_runs" ]]; then
+            echo "Too many runs already running"
+            echo "too_many_runs=true" >> "$GITHUB_OUTPUT"
+            exit 1
+          fi
+
+          sleep 60 # Poll every 60 seconds
+        done
+
+    - name: Retrieve Test Logs
+      if: always() && steps.poll_step.outputs.too_many_runs != 'true'
+      run: |
+        curl -k -X 'GET' \
+        "${EC2_MACHINE_URL_US}/test_log/${GITHUB_RUN_ID}" \
+        -H 'accept: application/gzip' \
+        -H "Authorization: Bearer $API_KEY" \
+        --output "test_log_${GITHUB_RUN_ID}.gz"
+    
+    - name: Unzip Test Log and Print it into this job's log
+      if: always() && steps.poll_step.outputs.too_many_runs != 'true'
+      run: |
+        gzip -d "test_log_${GITHUB_RUN_ID}.gz"
+        cat "test_log_${GITHUB_RUN_ID}"
+
+    - name: Create Allure report
+      env:
+        AWS_ACCESS_KEY_ID: ${{ secrets.AWS_ACCESS_KEY_DEV }}
+        AWS_SECRET_ACCESS_KEY: ${{ secrets.AWS_SECRET_KEY_DEV }}
+      if: ${{ !cancelled() }}
+      uses: ./.github/actions/allure-report-generate
+
+    - name: Post to a Slack channel
+      if: ${{ github.event.schedule && failure() }}
+      uses: slackapi/slack-github-action@v1
+      with:
+        channel-id: "C033QLM5P7D" # dev-staging-stream
+        slack-message: "Periodic pagebench testing on dedicated hardware: ${{ job.status }}\n${{ github.server_url }}/${{ github.repository }}/actions/runs/${{ github.run_id }}"
+      env:
+        SLACK_BOT_TOKEN: ${{ secrets.SLACK_BOT_TOKEN }}
+
+    - name: Cleanup Test Resources
+      if: always() 
+      run: |
+        curl -k -X 'POST' \
+        "${EC2_MACHINE_URL_US}/cleanup_test/${GITHUB_RUN_ID}" \
+        -H 'accept: application/json' \
+        -H "Authorization: Bearer $API_KEY" \
+        -d ''
+
+    - name: Stop EC2 instance and wait for the instance to be stopped
+      if: always() && steps.poll_step.outputs.too_many_runs != 'true'
+      run: |
+        aws ec2 stop-instances --instance-ids $AWS_INSTANCE_ID
+        aws ec2 wait instance-stopped --instance-ids $AWS_INSTANCE_ID
--- a/.github/workflows/pg-clients.yml
+++ b/.github/workflows/pg-clients.yml
@@ -0,0 +1,115 @@
+name: Test Postgres client libraries
+
+on:
+  schedule:
+    # * is a special character in YAML so you have to quote this string
+    #          ┌───────────── minute (0 - 59)
+    #          │ ┌───────────── hour (0 - 23)
+    #          │ │ ┌───────────── day of the month (1 - 31)
+    #          │ │ │ ┌───────────── month (1 - 12 or JAN-DEC)
+    #          │ │ │ │ ┌───────────── day of the week (0 - 6 or SUN-SAT)
+    - cron:  '23 02 * * *' # run once a day, timezone is utc
+  pull_request:
+    paths:
+      - '.github/workflows/pg-clients.yml'
+      - 'test_runner/pg_clients/**'
+      - 'poetry.lock'
+  workflow_dispatch:
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref_name }}
+  cancel-in-progress: ${{ github.event_name == 'pull_request' }}
+
+defaults:
+  run:
+    shell: bash -euxo pipefail {0}
+
+env:
+  DEFAULT_PG_VERSION: 16
+  PLATFORM: neon-captest-new
+  AWS_ACCESS_KEY_ID: ${{ secrets.AWS_ACCESS_KEY_DEV }}
+  AWS_SECRET_ACCESS_KEY: ${{ secrets.AWS_SECRET_KEY_DEV }}
+  AWS_DEFAULT_REGION: eu-central-1
+
+jobs:
+  check-permissions:
+    if: ${{ !contains(github.event.pull_request.labels.*.name, 'run-no-ci') }}
+    uses: ./.github/workflows/check-permissions.yml
+    with:
+      github-event-name: ${{ github.event_name }}
+
+  check-build-tools-image:
+    needs: [ check-permissions ]
+    uses: ./.github/workflows/check-build-tools-image.yml
+
+  build-build-tools-image:
+    needs: [ check-build-tools-image ]
+    uses: ./.github/workflows/build-build-tools-image.yml
+    with:
+      image-tag: ${{ needs.check-build-tools-image.outputs.image-tag }}
+    secrets: inherit
+
+  test-postgres-client-libs:
+    needs: [ build-build-tools-image ]
+    runs-on: ubuntu-22.04
+
+    container:
+      image: ${{ needs.build-build-tools-image.outputs.image }}
+      credentials:
+        username: ${{ secrets.NEON_DOCKERHUB_USERNAME }}
+        password: ${{ secrets.NEON_DOCKERHUB_PASSWORD }}
+      options: --init --user root
+
+    steps:
+    - uses: actions/checkout@v4
+
+    - name: Download Neon artifact
+      uses: ./.github/actions/download
+      with:
+        name: neon-${{ runner.os }}-${{ runner.arch }}-release-artifact
+        path: /tmp/neon/
+        prefix: latest
+
+    - name: Create Neon Project
+      id: create-neon-project
+      uses: ./.github/actions/neon-project-create
+      with:
+        api_key: ${{ secrets.NEON_STAGING_API_KEY }}
+        postgres_version: ${{ env.DEFAULT_PG_VERSION }}
+
+    - name: Run tests
+      uses: ./.github/actions/run-python-test-set
+      with:
+        build_type: remote
+        test_selection: pg_clients
+        run_in_parallel: false
+        extra_params: -m remote_cluster
+        pg_version: ${{ env.DEFAULT_PG_VERSION }}
+      env:
+        BENCHMARK_CONNSTR: ${{ steps.create-neon-project.outputs.dsn }}
+
+    - name: Delete Neon Project
+      if: always()
+      uses: ./.github/actions/neon-project-delete
+      with:
+        project_id: ${{ steps.create-neon-project.outputs.project_id }}
+        api_key: ${{ secrets.NEON_STAGING_API_KEY }}
+
+    - name: Create Allure report
+      if: ${{ !cancelled() }}
+      id: create-allure-report
+      uses: ./.github/actions/allure-report-generate
+      with:
+        store-test-results-into-db: true
+      env:
+        REGRESS_TEST_RESULT_CONNSTR_NEW: ${{ secrets.REGRESS_TEST_RESULT_CONNSTR_NEW }}
+
+    - name: Post to a Slack channel
+      if: github.event.schedule && failure()
+      uses: slackapi/slack-github-action@v1
+      with:
+        channel-id: "C06KHQVQ7U3" # on-call-qa-staging-stream
+        slack-message: |
+          Testing Postgres clients: <${{ github.server_url }}/${{ github.repository }}/actions/runs/${{ github.run_id }}|${{ job.status }}> (<${{ steps.create-allure-report.outputs.report-url }}|test report>)
+      env:
+        SLACK_BOT_TOKEN: ${{ secrets.SLACK_BOT_TOKEN }}
--- a/.github/workflows/pg_clients.yml
+++ b/.github/workflows/pg_clients.yml
@@ -1,98 +0,0 @@
-name: Test Postgres client libraries
-
-on:
-  schedule:
-    # * is a special character in YAML so you have to quote this string
-    #          ┌───────────── minute (0 - 59)
-    #          │ ┌───────────── hour (0 - 23)
-    #          │ │ ┌───────────── day of the month (1 - 31)
-    #          │ │ │ ┌───────────── month (1 - 12 or JAN-DEC)
-    #          │ │ │ │ ┌───────────── day of the week (0 - 6 or SUN-SAT)
-    - cron:  '23 02 * * *' # run once a day, timezone is utc
-
-  workflow_dispatch:
-
-concurrency:
-  # Allow only one workflow per any non-`main` branch.
-  group: ${{ github.workflow }}-${{ github.ref_name }}-${{ github.ref_name == 'main' && github.sha || 'anysha' }}
-  cancel-in-progress: true
-
-jobs:
-  test-postgres-client-libs:
-    # TODO: switch to gen2 runner, requires docker
-    runs-on: ubuntu-22.04
-
-    env:
-      DEFAULT_PG_VERSION: 14
-      TEST_OUTPUT: /tmp/test_output
-
-    steps:
-    - name: Checkout
-      uses: actions/checkout@v4
-
-    - uses: actions/setup-python@v4
-      with:
-        python-version: 3.9
-
-    - name: Install Poetry
-      uses: snok/install-poetry@v1
-
-    - name: Cache poetry deps
-      uses: actions/cache@v4
-      with:
-        path: ~/.cache/pypoetry/virtualenvs
-        key: v2-${{ runner.os }}-python-deps-ubunutu-latest-${{ hashFiles('poetry.lock') }}
-
-    - name: Install Python deps
-      shell: bash -euxo pipefail {0}
-      run: ./scripts/pysync
-
-    - name: Create Neon Project
-      id: create-neon-project
-      uses: ./.github/actions/neon-project-create
-      with:
-        api_key: ${{ secrets.NEON_STAGING_API_KEY }}
-        postgres_version: ${{ env.DEFAULT_PG_VERSION }}
-
-    - name: Run pytest
-      env:
-        REMOTE_ENV: 1
-        BENCHMARK_CONNSTR: ${{ steps.create-neon-project.outputs.dsn }}
-        POSTGRES_DISTRIB_DIR: /tmp/neon/pg_install
-      shell: bash -euxo pipefail {0}
-      run: |
-        # Test framework expects we have psql binary;
-        # but since we don't really need it in this test, let's mock it
-        mkdir -p "$POSTGRES_DISTRIB_DIR/v${DEFAULT_PG_VERSION}/bin" && touch "$POSTGRES_DISTRIB_DIR/v${DEFAULT_PG_VERSION}/bin/psql";
-        ./scripts/pytest \
-          --junitxml=$TEST_OUTPUT/junit.xml \
-          --tb=short \
-          --verbose \
-          -m "remote_cluster" \
-          -rA "test_runner/pg_clients"
-
-    - name: Delete Neon Project
-      if: ${{ always() }}
-      uses: ./.github/actions/neon-project-delete
-      with:
-        project_id: ${{ steps.create-neon-project.outputs.project_id }}
-        api_key: ${{ secrets.NEON_STAGING_API_KEY }}
-
-    # We use GitHub's action upload-artifact because `ubuntu-latest` doesn't have configured AWS CLI.
-    # It will be fixed after switching to gen2 runner
-    - name: Upload python test logs
-      if: always()
-      uses: actions/upload-artifact@v4
-      with:
-        retention-days: 7
-        name: python-test-pg_clients-${{ runner.os }}-stage-logs
-        path: ${{ env.TEST_OUTPUT }}
-
-    - name: Post to a Slack channel
-      if: ${{ github.event.schedule && failure() }}
-      uses: slackapi/slack-github-action@v1
-      with:
-        channel-id: "C033QLM5P7D" # dev-staging-stream
-        slack-message: "Testing Postgres clients: ${{ job.status }}\n${{ github.server_url }}/${{ github.repository }}/actions/runs/${{ github.run_id }}"
-      env:
-        SLACK_BOT_TOKEN: ${{ secrets.SLACK_BOT_TOKEN }}
--- a/.neon_clippy_args
+++ b/.neon_clippy_args
@@ -1,4 +1,5 @@
 # * `-A unknown_lints` – do not warn about unknown lint suppressions
 #                        that people with newer toolchains might use
 # * `-D warnings`      - fail on any warnings (`cargo` returns non-zero exit status)
-export CLIPPY_COMMON_ARGS="--locked --workspace --all-targets -- -A unknown_lints -D warnings"
+# * `-D clippy::todo`  - don't let `todo!()` slip into `main`
+export CLIPPY_COMMON_ARGS="--locked --workspace --all-targets -- -A unknown_lints -D warnings -D clippy::todo"
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -1014,6 +1014,9 @@ name = "camino"
 version = "1.1.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "c59e92b5a388f549b863a7bea62612c09f24c8393560709a54558a9abdfb3b9c"
+dependencies = [
+ "serde",
+]

 [[package]]
 name = "camino-tempfile"
@@ -1243,7 +1246,7 @@ dependencies = [
 "tokio-postgres",
 "tokio-stream",
 "tokio-util",
- "toml_edit",
+ "toml_edit 0.19.10",
 "tracing",
 "tracing-opentelemetry",
 "tracing-subscriber",
@@ -1359,8 +1362,8 @@ dependencies = [
 "tokio",
 "tokio-postgres",
 "tokio-util",
- "toml",
- "toml_edit",
+ "toml 0.7.4",
+ "toml_edit 0.19.10",
 "tracing",
 "url",
 "utils",
@@ -1666,9 +1669,9 @@ dependencies = [

 [[package]]
 name = "diesel"
-version = "2.1.4"
+version = "2.2.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "62c6fcf842f17f8c78ecf7c81d75c5ce84436b41ee07e03f490fbb5f5a8731d8"
+checksum = "62d6dcd069e7b5fe49a302411f759d4cf1cf2c27fe798ef46fb8baefc053dd2b"
 dependencies = [
 "bitflags 2.4.1",
 "byteorder",
@@ -1681,11 +1684,12 @@ dependencies = [

 [[package]]
 name = "diesel_derives"
-version = "2.1.2"
+version = "2.2.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "ef8337737574f55a468005a83499da720f20c65586241ffea339db9ecdfd2b44"
+checksum = "59de76a222c2b8059f789cbe07afbfd8deb8c31dd0bc2a21f85e256c1def8259"
 dependencies = [
 "diesel_table_macro_syntax",
+ "dsl_auto_type",
 "proc-macro2",
 "quote",
 "syn 2.0.52",
@@ -1693,9 +1697,9 @@ dependencies = [

 [[package]]
 name = "diesel_migrations"
-version = "2.1.0"
+version = "2.2.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "6036b3f0120c5961381b570ee20a02432d7e2d27ea60de9578799cf9156914ac"
+checksum = "8a73ce704bad4231f001bff3314d91dce4aba0770cee8b233991859abc15c1f6"
 dependencies = [
 "diesel",
 "migrations_internals",
@@ -1704,9 +1708,9 @@ dependencies = [

 [[package]]
 name = "diesel_table_macro_syntax"
-version = "0.1.0"
+version = "0.2.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "fc5557efc453706fed5e4fa85006fe9817c224c3f480a34c7e5959fd700921c5"
+checksum = "209c735641a413bc68c4923a9d6ad4bcb3ca306b794edaa7eb0b3228a99ffb25"
 dependencies = [
 "syn 2.0.52",
 ]
@@ -1742,6 +1746,20 @@ dependencies = [
 "const-random",
 ]

+[[package]]
+name = "dsl_auto_type"
+version = "0.1.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0892a17df262a24294c382f0d5997571006e7a4348b4327557c4ff1cd4a8bccc"
+dependencies = [
+ "darling",
+ "either",
+ "heck 0.5.0",
+ "proc-macro2",
+ "quote",
+ "syn 2.0.52",
+]
+
 [[package]]
 name = "dyn-clone"
 version = "1.0.14"
@@ -3081,19 +3099,19 @@ dependencies = [

 [[package]]
 name = "migrations_internals"
-version = "2.1.0"
+version = "2.2.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "0f23f71580015254b020e856feac3df5878c2c7a8812297edd6c0a485ac9dada"
+checksum = "fd01039851e82f8799046eabbb354056283fb265c8ec0996af940f4e85a380ff"
 dependencies = [
 "serde",
- "toml",
+ "toml 0.8.14",
 ]

 [[package]]
 name = "migrations_macros"
-version = "2.1.0"
+version = "2.2.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "cce3325ac70e67bbab5bd837a31cae01f1a6db64e0e744a33cb03a543469ef08"
+checksum = "ffb161cc72176cb37aa47f1fc520d3ef02263d67d661f44f05d05a079e1237fd"
 dependencies = [
 "migrations_internals",
 "proc-macro2",
@@ -3573,7 +3591,7 @@ dependencies = [
 "thiserror",
 "tokio",
 "tokio-util",
- "toml_edit",
+ "toml_edit 0.19.10",
 "utils",
 "workspace_hack",
 ]
@@ -3656,7 +3674,7 @@ dependencies = [
 "tokio-stream",
 "tokio-tar",
 "tokio-util",
- "toml_edit",
+ "toml_edit 0.19.10",
 "tracing",
 "twox-hash",
 "url",
@@ -4002,7 +4020,7 @@ dependencies = [
 [[package]]
 name = "postgres"
 version = "0.19.4"
-source = "git+https://github.com/neondatabase/rust-postgres.git?branch=neon#20031d7a9ee1addeae6e0968e3899ae6bf01cee2"
+source = "git+https://github.com/neondatabase/rust-postgres.git?branch=neon#cff6927e4f58b1af6ecc2ee7279df1f2ff537295"
 dependencies = [
 "bytes",
 "fallible-iterator",
@@ -4015,7 +4033,7 @@ dependencies = [
 [[package]]
 name = "postgres-protocol"
 version = "0.6.4"
-source = "git+https://github.com/neondatabase/rust-postgres.git?branch=neon#20031d7a9ee1addeae6e0968e3899ae6bf01cee2"
+source = "git+https://github.com/neondatabase/rust-postgres.git?branch=neon#cff6927e4f58b1af6ecc2ee7279df1f2ff537295"
 dependencies = [
 "base64 0.20.0",
 "byteorder",
@@ -4034,7 +4052,7 @@ dependencies = [
 [[package]]
 name = "postgres-types"
 version = "0.2.4"
-source = "git+https://github.com/neondatabase/rust-postgres.git?branch=neon#20031d7a9ee1addeae6e0968e3899ae6bf01cee2"
+source = "git+https://github.com/neondatabase/rust-postgres.git?branch=neon#cff6927e4f58b1af6ecc2ee7279df1f2ff537295"
 dependencies = [
 "bytes",
 "fallible-iterator",
@@ -4647,6 +4665,7 @@ dependencies = [
 "futures-util",
 "http-types",
 "humantime",
+ "humantime-serde",
 "hyper 0.14.26",
 "itertools",
 "metrics",
@@ -4661,7 +4680,7 @@ dependencies = [
 "tokio",
 "tokio-stream",
 "tokio-util",
- "toml_edit",
+ "toml_edit 0.19.10",
 "tracing",
 "utils",
 "workspace_hack",
@@ -5160,7 +5179,7 @@ dependencies = [
 "tokio-stream",
 "tokio-tar",
 "tokio-util",
- "toml_edit",
+ "toml_edit 0.19.10",
 "tracing",
 "tracing-subscriber",
 "url",
@@ -5439,9 +5458,9 @@ dependencies = [

 [[package]]
 name = "serde_spanned"
-version = "0.6.2"
+version = "0.6.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "93107647184f6027e3b7dcb2e11034cf95ffa1e3a682c67951963ac69c1c007d"
+checksum = "79e674e01f999af37c49f70a6ede167a8a60b2503e56c5599532a65baa5969a0"
 dependencies = [
 "serde",
 ]
@@ -6206,7 +6225,7 @@ dependencies = [
 [[package]]
 name = "tokio-postgres"
 version = "0.7.7"
-source = "git+https://github.com/neondatabase/rust-postgres.git?branch=neon#20031d7a9ee1addeae6e0968e3899ae6bf01cee2"
+source = "git+https://github.com/neondatabase/rust-postgres.git?branch=neon#cff6927e4f58b1af6ecc2ee7279df1f2ff537295"
 dependencies = [
 "async-trait",
 "byteorder",
@@ -6326,14 +6345,26 @@ dependencies = [
 "serde",
 "serde_spanned",
 "toml_datetime",
- "toml_edit",
+ "toml_edit 0.19.10",
+]
+
+[[package]]
+name = "toml"
+version = "0.8.14"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6f49eb2ab21d2f26bd6db7bf383edc527a7ebaee412d17af4d40fdccd442f335"
+dependencies = [
+ "serde",
+ "serde_spanned",
+ "toml_datetime",
+ "toml_edit 0.22.14",
 ]

 [[package]]
 name = "toml_datetime"
-version = "0.6.2"
+version = "0.6.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "5a76a9312f5ba4c2dec6b9161fdf25d87ad8a09256ccea5a556fef03c706a10f"
+checksum = "4badfd56924ae69bcc9039335b2e017639ce3f9b001c393c1b2d1ef846ce2cbf"
 dependencies = [
 "serde",
 ]
@@ -6348,7 +6379,20 @@ dependencies = [
 "serde",
 "serde_spanned",
 "toml_datetime",
- "winnow",
+ "winnow 0.4.6",
+]
+
+[[package]]
+name = "toml_edit"
+version = "0.22.14"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f21c7aaf97f1bd9ca9d4f9e73b0a6c74bd5afef56f2bc931943a6e1c37e04e38"
+dependencies = [
+ "indexmap 2.0.1",
+ "serde",
+ "serde_spanned",
+ "toml_datetime",
+ "winnow 0.6.13",
 ]

 [[package]]
@@ -6767,6 +6811,7 @@ dependencies = [
 "tokio-stream",
 "tokio-tar",
 "tokio-util",
+ "toml_edit 0.19.10",
 "tracing",
 "tracing-error",
 "tracing-subscriber",
@@ -7331,6 +7376,15 @@ dependencies = [
 "memchr",
 ]

+[[package]]
+name = "winnow"
+version = "0.6.13"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "59b5e5f6c299a3c7890b876a2a587f3115162487e704907d9b6cd29473052ba1"
+dependencies = [
+ "memchr",
+]
+
 [[package]]
 name = "winreg"
 version = "0.50.0"
@@ -7367,6 +7421,7 @@ dependencies = [
 "base64 0.21.1",
 "base64ct",
 "bytes",
+ "camino",
 "cc",
 "chrono",
 "clap",
@@ -7419,7 +7474,7 @@ dependencies = [
 "tokio-rustls 0.24.0",
 "tokio-util",
 "toml_datetime",
- "toml_edit",
+ "toml_edit 0.19.10",
 "tonic",
 "tower",
 "tracing",
--- a/5
+++ b/5
@@ -42,12 +42,13 @@ ARG CACHEPOT_BUCKET=neon-github-dev
 COPY --from=pg-build /home/nonroot/pg_install/v14/include/postgresql/server pg_install/v14/include/postgresql/server
 COPY --from=pg-build /home/nonroot/pg_install/v15/include/postgresql/server pg_install/v15/include/postgresql/server
 COPY --from=pg-build /home/nonroot/pg_install/v16/include/postgresql/server pg_install/v16/include/postgresql/server
+COPY --from=pg-build /home/nonroot/pg_install/v16/lib                       pg_install/v16/lib
 COPY --chown=nonroot . .

 # Show build caching stats to check if it was used in the end.
 # Has to be the part of the same RUN since cachepot daemon is killed in the end of this RUN, losing the compilation stats.
 RUN set -e \
-    && RUSTFLAGS="-Clinker=clang -Clink-arg=-fuse-ld=mold -Clink-arg=-Wl,--no-rosegment" cargo build  \
+    && PQ_LIB_DIR=$(pwd)/pg_install/v16/lib RUSTFLAGS="-Clinker=clang -Clink-arg=-fuse-ld=mold -Clink-arg=-Wl,--no-rosegment" cargo build \
      --bin pg_sni_router  \
      --bin pageserver  \
      --bin pagectl  \
@@ -56,6 +57,7 @@ RUN set -e \
      --bin storage_controller  \
      --bin proxy  \
      --bin neon_local \
+      --bin storage_scrubber \
      --locked --release \
    && cachepot -s

@@ -82,6 +84,7 @@ COPY --from=build --chown=neon:neon /home/nonroot/target/release/storage_broker
 COPY --from=build --chown=neon:neon /home/nonroot/target/release/storage_controller  /usr/local/bin
 COPY --from=build --chown=neon:neon /home/nonroot/target/release/proxy               /usr/local/bin
 COPY --from=build --chown=neon:neon /home/nonroot/target/release/neon_local          /usr/local/bin
+COPY --from=build --chown=neon:neon /home/nonroot/target/release/storage_scrubber    /usr/local/bin

 COPY --from=pg-build /home/nonroot/pg_install/v14 /usr/local/v14/
 COPY --from=pg-build /home/nonroot/pg_install/v15 /usr/local/v15/
--- a/Dockerfile.build-tools
+++ b/Dockerfile.build-tools
@@ -1,5 +1,13 @@
 FROM debian:bullseye-slim

+# Use ARG as a build-time environment variable here to allow.
+# It's not supposed to be set outside.
+# Alternatively it can be obtained using the following command
+# ```
+# . /etc/os-release && echo "${VERSION_CODENAME}"
+# ```
+ARG DEBIAN_VERSION_CODENAME=bullseye
+
 # Add nonroot user
 RUN useradd -ms /bin/bash nonroot -b /home
 SHELL ["/bin/bash", "-c"]
@@ -26,7 +34,6 @@ RUN set -e \
        liblzma-dev \
        libncurses5-dev \
        libncursesw5-dev \
-        libpq-dev \
        libreadline-dev \
        libseccomp-dev \
        libsqlite3-dev \
@@ -67,19 +74,24 @@ RUN curl -sL "https://github.com/peak/s5cmd/releases/download/v${S5CMD_VERSION}/
 # LLVM
 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-${LLVM_VERSION} main" > /etc/apt/sources.list.d/llvm.stable.list \
+    && echo "deb http://apt.llvm.org/${DEBIAN_VERSION_CODENAME}/ llvm-toolchain-${DEBIAN_VERSION_CODENAME}-${LLVM_VERSION} main" > /etc/apt/sources.list.d/llvm.stable.list \
    && apt update \
    && apt install -y clang-${LLVM_VERSION} llvm-${LLVM_VERSION} \
    && bash -c 'for f in /usr/bin/clang*-${LLVM_VERSION} /usr/bin/llvm*-${LLVM_VERSION}; do ln -s "${f}" "${f%-${LLVM_VERSION}}"; done' \
    && rm -rf /var/lib/apt/lists/* /tmp/* /var/tmp/*

-# PostgreSQL 14
-RUN curl -fsSL 'https://www.postgresql.org/media/keys/ACCC4CF8.asc' | apt-key add - \
-    && echo 'deb http://apt.postgresql.org/pub/repos/apt bullseye-pgdg main' > /etc/apt/sources.list.d/pgdg.list \
+# Install docker
+RUN curl -fsSL https://download.docker.com/linux/ubuntu/gpg | gpg --dearmor -o /usr/share/keyrings/docker-archive-keyring.gpg \
+    && echo "deb [arch=$(dpkg --print-architecture) signed-by=/usr/share/keyrings/docker-archive-keyring.gpg] https://download.docker.com/linux/debian ${DEBIAN_VERSION_CODENAME} stable" > /etc/apt/sources.list.d/docker.list \
    && apt update \
-    && apt install -y postgresql-client-14 \
+    && apt install -y docker-ce docker-ce-cli \
    && rm -rf /var/lib/apt/lists/* /tmp/* /var/tmp/*

+# Configure sudo & docker
+RUN usermod -aG sudo nonroot && \
+    echo '%sudo ALL=(ALL) NOPASSWD:ALL' >> /etc/sudoers && \
+    usermod -aG docker nonroot
+
 # AWS CLI
 RUN curl "https://awscli.amazonaws.com/awscli-exe-linux-$(uname -m).zip" -o "awscliv2.zip" \
    && unzip -q awscliv2.zip \
@@ -113,10 +125,10 @@ RUN for package in Capture::Tiny DateTime Devel::Cover Digest::MD5 File::Spec JS
    && rm -rf ../lcov.tar.gz

 # Compile and install the static OpenSSL library
-ENV OPENSSL_VERSION=3.2.2
+ENV OPENSSL_VERSION=1.1.1w
 ENV OPENSSL_PREFIX=/usr/local/openssl
 RUN wget -O /tmp/openssl-${OPENSSL_VERSION}.tar.gz https://www.openssl.org/source/openssl-${OPENSSL_VERSION}.tar.gz && \
-    echo "197149c18d9e9f292c43f0400acaba12e5f52cacfe050f3d199277ea738ec2e7 /tmp/openssl-${OPENSSL_VERSION}.tar.gz" | sha256sum --check && \
+    echo "cf3098950cb4d853ad95c0841f1f9c6d3dc102dccfcacd521d93925208b76ac8 /tmp/openssl-${OPENSSL_VERSION}.tar.gz" | sha256sum --check && \
    cd /tmp && \
    tar xzvf /tmp/openssl-${OPENSSL_VERSION}.tar.gz && \
    rm /tmp/openssl-${OPENSSL_VERSION}.tar.gz && \
--- a/Dockerfile.compute-node
+++ b/Dockerfile.compute-node
@@ -467,31 +467,6 @@ RUN case "${PG_VERSION}" in \
    make install -j $(getconf _NPROCESSORS_ONLN) && \
    echo "trusted = true" >> /usr/local/pgsql/share/extension/pg_hint_plan.control

-#########################################################################################
-#
-# Layer "kq-imcx-pg-build"
-# compile kq_imcx extension
-#
-#########################################################################################
-FROM build-deps AS kq-imcx-pg-build
-COPY --from=pg-build /usr/local/pgsql/ /usr/local/pgsql/
-
-ENV PATH "/usr/local/pgsql/bin/:$PATH"
-RUN apt-get update && \
-    apt-get install -y git libgtk2.0-dev libpq-dev libpam-dev libxslt-dev libkrb5-dev cmake && \
-    wget https://github.com/ketteq-neon/postgres-exts/archive/e0bd1a9d9313d7120c1b9c7bb15c48c0dede4c4e.tar.gz -O kq_imcx.tar.gz && \
-    echo "dc93a97ff32d152d32737ba7e196d9687041cda15e58ab31344c2f2de8855336 kq_imcx.tar.gz" | sha256sum --check && \
-    mkdir kq_imcx-src && cd kq_imcx-src && tar xzf ../kq_imcx.tar.gz --strip-components=1 -C . && \
-    find /usr/local/pgsql -type f | sed 's|^/usr/local/pgsql/||' > /before.txt &&\
-    mkdir build && cd build && \
-    cmake -DCMAKE_BUILD_TYPE=Release .. && \
-    make -j $(getconf _NPROCESSORS_ONLN) && \
-    make -j $(getconf _NPROCESSORS_ONLN) install && \
-    echo 'trusted = true' >> /usr/local/pgsql/share/extension/kq_imcx.control && \
-    find /usr/local/pgsql -type f | sed 's|^/usr/local/pgsql/||' > /after.txt &&\
-    mkdir -p /extensions/kq_imcx && cp /usr/local/pgsql/share/extension/kq_imcx.control /extensions/kq_imcx && \
-    sort -o /before.txt /before.txt && sort -o /after.txt /after.txt && \
-    comm -13 /before.txt /after.txt | tar --directory=/usr/local/pgsql --zstd -cf /extensions/kq_imcx.tar.zst -T -

 #########################################################################################
 #
@@ -840,7 +815,6 @@ COPY --from=hll-pg-build /usr/local/pgsql/ /usr/local/pgsql/
 COPY --from=plpgsql-check-pg-build /usr/local/pgsql/ /usr/local/pgsql/
 COPY --from=timescaledb-pg-build /usr/local/pgsql/ /usr/local/pgsql/
 COPY --from=pg-hint-plan-pg-build /usr/local/pgsql/ /usr/local/pgsql/
-COPY --from=kq-imcx-pg-build /usr/local/pgsql/ /usr/local/pgsql/
 COPY --from=pg-cron-pg-build /usr/local/pgsql/ /usr/local/pgsql/
 COPY --from=pg-pgx-ulid-build /usr/local/pgsql/ /usr/local/pgsql/
 COPY --from=rdkit-pg-build /usr/local/pgsql/ /usr/local/pgsql/
@@ -961,7 +935,6 @@ COPY --from=plpgsql-check-pg-build /plpgsql_check.tar.gz /ext-src
 #COPY --from=timescaledb-pg-build /timescaledb.tar.gz /ext-src
 COPY --from=pg-hint-plan-pg-build /pg_hint_plan.tar.gz /ext-src
 COPY patches/pg_hintplan.patch /ext-src
-#COPY --from=kq-imcx-pg-build /kq_imcx.tar.gz /ext-src
 COPY --from=pg-cron-pg-build /pg_cron.tar.gz /ext-src
 COPY patches/pg_cron.patch /ext-src
 #COPY --from=pg-pgx-ulid-build /home/nonroot/pgx_ulid.tar.gz /ext-src
--- a/compute_tools/src/compute.rs
+++ b/compute_tools/src/compute.rs
@@ -873,9 +873,8 @@ impl ComputeNode {
        Ok(())
    }

-    // We could've wrapped this around `pg_ctl reload`, but right now we don't use
-    // `pg_ctl` for start / stop, so this just seems much easier to do as we already
-    // have opened connection to Postgres and superuser access.
+    // Wrapped this around `pg_ctl reload`, but right now we don't use
+    // `pg_ctl` for start / stop.
    #[instrument(skip_all)]
    fn pg_reload_conf(&self) -> Result<()> {
        let pgctl_bin = Path::new(&self.pgbin).parent().unwrap().join("pg_ctl");
--- a/compute_tools/src/config.rs
+++ b/compute_tools/src/config.rs
@@ -83,12 +83,6 @@ pub fn write_postgres_conf(
        ComputeMode::Replica => {
            // hot_standby is 'on' by default, but let's be explicit
            writeln!(file, "hot_standby=on")?;
-
-            // Inform the replica about the primary state
-            // Default is 'false'
-            if let Some(primary_is_running) = spec.primary_is_running {
-                writeln!(file, "neon.primary_is_running={}", primary_is_running)?;
-            }
        }
    }

--- a/compute_tools/src/monitor.rs
+++ b/compute_tools/src/monitor.rs
@@ -17,7 +17,11 @@ const MONITOR_CHECK_INTERVAL: Duration = Duration::from_millis(500);
 // should be handled gracefully.
 fn watch_compute_activity(compute: &ComputeNode) {
    // Suppose that `connstr` doesn't change
-    let connstr = compute.connstr.as_str();
+    let mut connstr = compute.connstr.clone();
+    connstr
+        .query_pairs_mut()
+        .append_pair("application_name", "compute_activity_monitor");
+    let connstr = connstr.as_str();

    // During startup and configuration we connect to every Postgres database,
    // but we don't want to count this as some user activity. So wait until
--- a/compute_tools/src/pg_helpers.rs
+++ b/compute_tools/src/pg_helpers.rs
@@ -489,7 +489,7 @@ pub fn handle_postgres_logs(stderr: std::process::ChildStderr) -> JoinHandle<()>
 /// Read Postgres logs from `stderr` until EOF. Buffer is flushed on one of the following conditions:
 /// - next line starts with timestamp
 /// - EOF
-/// - no new lines were written for the last second
+/// - no new lines were written for the last 100 milliseconds
 async fn handle_postgres_logs_async(stderr: tokio::process::ChildStderr) -> Result<()> {
    let mut lines = tokio::io::BufReader::new(stderr).lines();
    let timeout_duration = Duration::from_millis(100);
--- a/control_plane/src/bin/neon_local.rs
+++ b/control_plane/src/bin/neon_local.rs
@@ -21,10 +21,8 @@ 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::controller_api::{PlacementPolicy, TenantCreateRequest};
+use pageserver_api::models::{ShardParameters, TimelineCreateRequest, TimelineInfo};
 use pageserver_api::shard::{ShardCount, ShardStripeSize, TenantShardId};
 use postgres_backend::AuthType;
 use postgres_connection::parse_host_port;
@@ -600,13 +598,9 @@ async fn handle_timeline(timeline_match: &ArgMatches, env: &mut local_env::Local
        Some(("import", import_match)) => {
            let tenant_id = get_tenant_id(import_match, env)?;
            let timeline_id = parse_timeline_id(import_match)?.expect("No timeline id provided");
-            let name = import_match
-                .get_one::<String>("node-name")
-                .ok_or_else(|| anyhow!("No node name provided"))?;
-            let update_catalog = import_match
-                .get_one::<bool>("update-catalog")
-                .cloned()
-                .unwrap_or_default();
+            let branch_name = import_match
+                .get_one::<String>("branch-name")
+                .ok_or_else(|| anyhow!("No branch name provided"))?;

            // Parse base inputs
            let base_tarfile = import_match
@@ -633,24 +627,11 @@ async fn handle_timeline(timeline_match: &ArgMatches, env: &mut local_env::Local
                .copied()
                .context("Failed to parse postgres version from the argument string")?;

-            let mut cplane = ComputeControlPlane::load(env.clone())?;
            println!("Importing timeline into pageserver ...");
            pageserver
                .timeline_import(tenant_id, timeline_id, base, pg_wal, pg_version)
                .await?;
-            env.register_branch_mapping(name.to_string(), tenant_id, timeline_id)?;
-
-            println!("Creating endpoint for imported timeline ...");
-            cplane.new_endpoint(
-                name,
-                tenant_id,
-                timeline_id,
-                None,
-                None,
-                pg_version,
-                ComputeMode::Primary,
-                !update_catalog,
-            )?;
+            env.register_branch_mapping(branch_name.to_string(), tenant_id, timeline_id)?;
            println!("Done");
        }
        Some(("branch", branch_match)) => {
@@ -865,20 +846,13 @@ async fn handle_endpoint(ep_match: &ArgMatches, env: &local_env::LocalEnv) -> Re

            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") {
-                    let mut safekeepers: Vec<NodeId> = Vec::new();
-                    for sk_id in safekeepers_str.split(',').map(str::trim) {
-                        let sk_id = NodeId(u64::from_str(sk_id).map_err(|_| {
-                            anyhow!("invalid node ID \"{sk_id}\" in --safekeepers list")
-                        })?);
-                        safekeepers.push(sk_id);
-                    }
-                    safekeepers
-                } else {
-                    env.safekeepers.iter().map(|sk| sk.id).collect()
-                };
+            // If --safekeepers argument is given, use only the listed
+            // safekeeper nodes; otherwise all from the env.
+            let safekeepers = if let Some(safekeepers) = parse_safekeepers(sub_args)? {
+                safekeepers
+            } else {
+                env.safekeepers.iter().map(|sk| sk.id).collect()
+            };

            let endpoint = cplane
                .endpoints
@@ -982,7 +956,10 @@ async fn handle_endpoint(ep_match: &ArgMatches, env: &local_env::LocalEnv) -> Re
                        })
                        .collect::<Vec<_>>()
                };
-            endpoint.reconfigure(pageservers, None).await?;
+            // If --safekeepers argument is given, use only the listed
+            // safekeeper nodes; otherwise all from the env.
+            let safekeepers = parse_safekeepers(sub_args)?;
+            endpoint.reconfigure(pageservers, None, safekeepers).await?;
        }
        "stop" => {
            let endpoint_id = sub_args
@@ -1004,6 +981,23 @@ async fn handle_endpoint(ep_match: &ArgMatches, env: &local_env::LocalEnv) -> Re
    Ok(())
 }

+/// Parse --safekeepers as list of safekeeper ids.
+fn parse_safekeepers(sub_args: &ArgMatches) -> Result<Option<Vec<NodeId>>> {
+    if let Some(safekeepers_str) = sub_args.get_one::<String>("safekeepers") {
+        let mut safekeepers: Vec<NodeId> = Vec::new();
+        for sk_id in safekeepers_str.split(',').map(str::trim) {
+            let sk_id = NodeId(
+                u64::from_str(sk_id)
+                    .map_err(|_| anyhow!("invalid node ID \"{sk_id}\" in --safekeepers list"))?,
+            );
+            safekeepers.push(sk_id);
+        }
+        Ok(Some(safekeepers))
+    } else {
+        Ok(None)
+    }
+}
+
 fn handle_mappings(sub_match: &ArgMatches, env: &mut local_env::LocalEnv) -> Result<()> {
    let (sub_name, sub_args) = match sub_match.subcommand() {
        Some(ep_subcommand_data) => ep_subcommand_data,
@@ -1487,8 +1481,7 @@ fn cli() -> Command {
                .about("Import timeline from basebackup directory")
                .arg(tenant_id_arg.clone())
                .arg(timeline_id_arg.clone())
-                .arg(Arg::new("node-name").long("node-name")
-                    .help("Name to assign to the imported timeline"))
+                .arg(branch_name_arg.clone())
                .arg(Arg::new("base-tarfile")
                    .long("base-tarfile")
                    .value_parser(value_parser!(PathBuf))
@@ -1504,7 +1497,6 @@ fn cli() -> Command {
                .arg(Arg::new("end-lsn").long("end-lsn")
                    .help("Lsn the basebackup ends at"))
                .arg(pg_version_arg.clone())
-                .arg(update_catalog.clone())
            )
        ).subcommand(
            Command::new("tenant")
@@ -1609,7 +1601,7 @@ fn cli() -> Command {
                    .about("Start postgres.\n If the endpoint doesn't exist yet, it is created.")
                    .arg(endpoint_id_arg.clone())
                    .arg(endpoint_pageserver_id_arg.clone())
-                    .arg(safekeepers_arg)
+                    .arg(safekeepers_arg.clone())
                    .arg(remote_ext_config_args)
                    .arg(create_test_user)
                    .arg(allow_multiple.clone())
@@ -1618,6 +1610,7 @@ fn cli() -> Command {
                .subcommand(Command::new("reconfigure")
                            .about("Reconfigure the endpoint")
                            .arg(endpoint_pageserver_id_arg)
+                            .arg(safekeepers_arg)
                            .arg(endpoint_id_arg.clone())
                            .arg(tenant_id_arg.clone())
                )
--- a/control_plane/src/endpoint.rs
+++ b/control_plane/src/endpoint.rs
@@ -499,6 +499,23 @@ impl Endpoint {
            .join(",")
    }

+    /// Map safekeepers ids to the actual connection strings.
+    fn build_safekeepers_connstrs(&self, sk_ids: Vec<NodeId>) -> Result<Vec<String>> {
+        let mut safekeeper_connstrings = Vec::new();
+        if self.mode == ComputeMode::Primary {
+            for sk_id in sk_ids {
+                let sk = self
+                    .env
+                    .safekeepers
+                    .iter()
+                    .find(|node| node.id == sk_id)
+                    .ok_or_else(|| anyhow!("safekeeper {sk_id} does not exist"))?;
+                safekeeper_connstrings.push(format!("127.0.0.1:{}", sk.get_compute_port()));
+            }
+        }
+        Ok(safekeeper_connstrings)
+    }
+
    pub async fn start(
        &self,
        auth_token: &Option<String>,
@@ -523,18 +540,7 @@ impl Endpoint {
        let pageserver_connstring = Self::build_pageserver_connstr(&pageservers);
        assert!(!pageserver_connstring.is_empty());

-        let mut safekeeper_connstrings = Vec::new();
-        if self.mode == ComputeMode::Primary {
-            for sk_id in safekeepers {
-                let sk = self
-                    .env
-                    .safekeepers
-                    .iter()
-                    .find(|node| node.id == sk_id)
-                    .ok_or_else(|| anyhow!("safekeeper {sk_id} does not exist"))?;
-                safekeeper_connstrings.push(format!("127.0.0.1:{}", sk.get_compute_port()));
-            }
-        }
+        let safekeeper_connstrings = self.build_safekeepers_connstrs(safekeepers)?;

        // check for file remote_extensions_spec.json
        // if it is present, read it and pass to compute_ctl
@@ -592,7 +598,6 @@ impl Endpoint {
            remote_extensions,
            pgbouncer_settings: None,
            shard_stripe_size: Some(shard_stripe_size),
-            primary_is_running: None,
        };
        let spec_path = self.endpoint_path().join("spec.json");
        std::fs::write(spec_path, serde_json::to_string_pretty(&spec)?)?;
@@ -741,6 +746,7 @@ impl Endpoint {
        &self,
        mut pageservers: Vec<(Host, u16)>,
        stripe_size: Option<ShardStripeSize>,
+        safekeepers: Option<Vec<NodeId>>,
    ) -> Result<()> {
        let mut spec: ComputeSpec = {
            let spec_path = self.endpoint_path().join("spec.json");
@@ -775,6 +781,12 @@ impl Endpoint {
            spec.shard_stripe_size = stripe_size.map(|s| s.0 as usize);
        }

+        // If safekeepers are not specified, don't change them.
+        if let Some(safekeepers) = safekeepers {
+            let safekeeper_connstrings = self.build_safekeepers_connstrs(safekeepers)?;
+            spec.safekeeper_connstrings = safekeeper_connstrings;
+        }
+
        let client = reqwest::Client::builder()
            .timeout(Duration::from_secs(30))
            .build()
--- a/control_plane/src/local_env.rs
+++ b/control_plane/src/local_env.rs
@@ -325,11 +325,16 @@ impl LocalEnv {
        }
    }

-    pub fn pg_bin_dir(&self, pg_version: u32) -> anyhow::Result<PathBuf> {
-        Ok(self.pg_distrib_dir(pg_version)?.join("bin"))
+    pub fn pg_dir(&self, pg_version: u32, dir_name: &str) -> anyhow::Result<PathBuf> {
+        Ok(self.pg_distrib_dir(pg_version)?.join(dir_name))
    }
+
+    pub fn pg_bin_dir(&self, pg_version: u32) -> anyhow::Result<PathBuf> {
+        self.pg_dir(pg_version, "bin")
+    }
+
    pub fn pg_lib_dir(&self, pg_version: u32) -> anyhow::Result<PathBuf> {
-        Ok(self.pg_distrib_dir(pg_version)?.join("lib"))
+        self.pg_dir(pg_version, "lib")
    }

    pub fn pageserver_bin(&self) -> PathBuf {
--- a/control_plane/src/pageserver.rs
+++ b/control_plane/src/pageserver.rs
@@ -17,8 +17,7 @@ use anyhow::{bail, Context};
 use camino::Utf8PathBuf;
 use futures::SinkExt;
 use pageserver_api::models::{
-    self, AuxFilePolicy, LocationConfig, ShardParameters, TenantHistorySize, TenantInfo,
-    TimelineInfo,
+    self, AuxFilePolicy, LocationConfig, TenantHistorySize, TenantInfo, TimelineInfo,
 };
 use pageserver_api::shard::TenantShardId;
 use pageserver_client::mgmt_api;
@@ -397,28 +396,6 @@ impl PageServerNode {
        }
    }

-    pub async fn tenant_create(
-        &self,
-        new_tenant_id: TenantId,
-        generation: Option<u32>,
-        settings: HashMap<&str, &str>,
-    ) -> anyhow::Result<TenantId> {
-        let config = Self::parse_config(settings.clone())?;
-
-        let request = models::TenantCreateRequest {
-            new_tenant_id: TenantShardId::unsharded(new_tenant_id),
-            generation,
-            config,
-            shard_parameters: ShardParameters::default(),
-            // Placement policy is not meaningful for creations not done via storage controller
-            placement_policy: None,
-        };
-        if !settings.is_empty() {
-            bail!("Unrecognized tenant settings: {settings:?}")
-        }
-        Ok(self.http_client.tenant_create(&request).await?)
-    }
-
    pub async fn tenant_config(
        &self,
        tenant_id: TenantId,
--- a/control_plane/src/storage_controller.rs
+++ b/control_plane/src/storage_controller.rs
@@ -5,12 +5,11 @@ use crate::{
 use camino::{Utf8Path, Utf8PathBuf};
 use pageserver_api::{
    controller_api::{
-        NodeConfigureRequest, NodeRegisterRequest, TenantCreateResponse, TenantLocateResponse,
-        TenantShardMigrateRequest, TenantShardMigrateResponse,
+        NodeConfigureRequest, NodeRegisterRequest, TenantCreateRequest, TenantCreateResponse,
+        TenantLocateResponse, TenantShardMigrateRequest, TenantShardMigrateResponse,
    },
    models::{
-        TenantCreateRequest, TenantShardSplitRequest, TenantShardSplitResponse,
-        TimelineCreateRequest, TimelineInfo,
+        TenantShardSplitRequest, TenantShardSplitResponse, TimelineCreateRequest, TimelineInfo,
    },
    shard::{ShardStripeSize, TenantShardId},
 };
@@ -156,16 +155,16 @@ impl StorageController {
        .expect("non-Unicode path")
    }

-    /// Find the directory containing postgres binaries, such as `initdb` and `pg_ctl`
+    /// Find the directory containing postgres subdirectories, such `bin` and `lib`
    ///
    /// This usually uses STORAGE_CONTROLLER_POSTGRES_VERSION of postgres, but will fall back
    /// to other versions if that one isn't found.  Some automated tests create circumstances
    /// where only one version is available in pg_distrib_dir, such as `test_remote_extensions`.
-    pub async fn get_pg_bin_dir(&self) -> anyhow::Result<Utf8PathBuf> {
+    async fn get_pg_dir(&self, dir_name: &str) -> anyhow::Result<Utf8PathBuf> {
        let prefer_versions = [STORAGE_CONTROLLER_POSTGRES_VERSION, 15, 14];

        for v in prefer_versions {
-            let path = Utf8PathBuf::from_path_buf(self.env.pg_bin_dir(v)?).unwrap();
+            let path = Utf8PathBuf::from_path_buf(self.env.pg_dir(v, dir_name)?).unwrap();
            if tokio::fs::try_exists(&path).await? {
                return Ok(path);
            }
@@ -173,11 +172,20 @@ impl StorageController {

        // Fall through
        anyhow::bail!(
-            "Postgres binaries not found in {}",
-            self.env.pg_distrib_dir.display()
+            "Postgres directory '{}' not found in {}",
+            dir_name,
+            self.env.pg_distrib_dir.display(),
        );
    }

+    pub async fn get_pg_bin_dir(&self) -> anyhow::Result<Utf8PathBuf> {
+        self.get_pg_dir("bin").await
+    }
+
+    pub async fn get_pg_lib_dir(&self) -> anyhow::Result<Utf8PathBuf> {
+        self.get_pg_dir("lib").await
+    }
+
    /// Readiness check for our postgres process
    async fn pg_isready(&self, pg_bin_dir: &Utf8Path) -> anyhow::Result<bool> {
        let bin_path = pg_bin_dir.join("pg_isready");
@@ -230,12 +238,17 @@ impl StorageController {
            .unwrap()
            .join("storage_controller_db");
        let pg_bin_dir = self.get_pg_bin_dir().await?;
+        let pg_lib_dir = self.get_pg_lib_dir().await?;
        let pg_log_path = pg_data_path.join("postgres.log");

        if !tokio::fs::try_exists(&pg_data_path).await? {
            // Initialize empty database
            let initdb_path = pg_bin_dir.join("initdb");
            let mut child = Command::new(&initdb_path)
+                .envs(vec![
+                    ("LD_LIBRARY_PATH".to_owned(), pg_lib_dir.to_string()),
+                    ("DYLD_LIBRARY_PATH".to_owned(), pg_lib_dir.to_string()),
+                ])
                .args(["-D", pg_data_path.as_ref()])
                .spawn()
                .expect("Failed to spawn initdb");
@@ -270,7 +283,10 @@ impl StorageController {
            &self.env.base_data_dir,
            pg_bin_dir.join("pg_ctl").as_std_path(),
            db_start_args,
-            [],
+            vec![
+                ("LD_LIBRARY_PATH".to_owned(), pg_lib_dir.to_string()),
+                ("DYLD_LIBRARY_PATH".to_owned(), pg_lib_dir.to_string()),
+            ],
            background_process::InitialPidFile::Create(self.postgres_pid_file()),
            retry_timeout,
            || self.pg_isready(&pg_bin_dir),
@@ -325,7 +341,10 @@ impl StorageController {
            &self.env.base_data_dir,
            &self.env.storage_controller_bin(),
            args,
-            [],
+            vec![
+                ("LD_LIBRARY_PATH".to_owned(), pg_lib_dir.to_string()),
+                ("DYLD_LIBRARY_PATH".to_owned(), pg_lib_dir.to_string()),
+            ],
            background_process::InitialPidFile::Create(self.pid_file()),
            retry_timeout,
            || async {
--- a/control_plane/storcon_cli/src/main.rs
+++ b/control_plane/storcon_cli/src/main.rs
@@ -1,16 +1,16 @@
 use futures::StreamExt;
-use std::{collections::HashMap, str::FromStr, time::Duration};
+use std::{str::FromStr, time::Duration};

 use clap::{Parser, Subcommand};
 use pageserver_api::{
    controller_api::{
-        NodeAvailabilityWrapper, NodeDescribeResponse, ShardSchedulingPolicy,
+        NodeAvailabilityWrapper, NodeDescribeResponse, ShardSchedulingPolicy, TenantCreateRequest,
        TenantDescribeResponse, TenantPolicyRequest,
    },
    models::{
        EvictionPolicy, EvictionPolicyLayerAccessThreshold, LocationConfigSecondary,
-        ShardParameters, TenantConfig, TenantConfigRequest, TenantCreateRequest,
-        TenantShardSplitRequest, TenantShardSplitResponse,
+        ShardParameters, TenantConfig, TenantConfigRequest, TenantShardSplitRequest,
+        TenantShardSplitResponse,
    },
    shard::{ShardStripeSize, TenantShardId},
 };
@@ -21,7 +21,7 @@ use utils::id::{NodeId, TenantId};

 use pageserver_api::controller_api::{
    NodeConfigureRequest, NodeRegisterRequest, NodeSchedulingPolicy, PlacementPolicy,
-    TenantLocateResponse, TenantShardMigrateRequest, TenantShardMigrateResponse,
+    TenantShardMigrateRequest, TenantShardMigrateResponse,
 };

 #[derive(Subcommand, Debug)]
@@ -110,12 +110,6 @@ enum Command {
        #[arg(long)]
        config: String,
    },
-    /// Attempt to balance the locations for a tenant across pageservers.  This is a client-side
-    /// alternative to the storage controller's scheduling optimization behavior.
-    TenantScatter {
-        #[arg(long)]
-        tenant_id: TenantId,
-    },
    /// Print details about a particular tenant, including all its shards' states.
    TenantDescribe {
        #[arg(long)]
@@ -342,14 +336,18 @@ async fn main() -> anyhow::Result<()> {
                .await?;
        }
        Command::TenantCreate { tenant_id } => {
-            vps_client
-                .tenant_create(&TenantCreateRequest {
-                    new_tenant_id: TenantShardId::unsharded(tenant_id),
-                    generation: None,
-                    shard_parameters: ShardParameters::default(),
-                    placement_policy: Some(PlacementPolicy::Attached(1)),
-                    config: TenantConfig::default(),
-                })
+            storcon_client
+                .dispatch(
+                    Method::POST,
+                    "v1/tenant".to_string(),
+                    Some(TenantCreateRequest {
+                        new_tenant_id: TenantShardId::unsharded(tenant_id),
+                        generation: None,
+                        shard_parameters: ShardParameters::default(),
+                        placement_policy: Some(PlacementPolicy::Attached(1)),
+                        config: TenantConfig::default(),
+                    }),
+                )
                .await?;
        }
        Command::TenantDelete { tenant_id } => {
@@ -498,88 +496,6 @@ async fn main() -> anyhow::Result<()> {
                })
                .await?;
        }
-        Command::TenantScatter { tenant_id } => {
-            // Find the shards
-            let locate_response = storcon_client
-                .dispatch::<(), TenantLocateResponse>(
-                    Method::GET,
-                    format!("control/v1/tenant/{tenant_id}/locate"),
-                    None,
-                )
-                .await?;
-            let shards = locate_response.shards;
-
-            let mut node_to_shards: HashMap<NodeId, Vec<TenantShardId>> = HashMap::new();
-            let shard_count = shards.len();
-            for s in shards {
-                let entry = node_to_shards.entry(s.node_id).or_default();
-                entry.push(s.shard_id);
-            }
-
-            // Load list of available nodes
-            let nodes_resp = storcon_client
-                .dispatch::<(), Vec<NodeDescribeResponse>>(
-                    Method::GET,
-                    "control/v1/node".to_string(),
-                    None,
-                )
-                .await?;
-
-            for node in nodes_resp {
-                if matches!(node.availability, NodeAvailabilityWrapper::Active) {
-                    node_to_shards.entry(node.id).or_default();
-                }
-            }
-
-            let max_shard_per_node = shard_count / node_to_shards.len();
-
-            loop {
-                let mut migrate_shard = None;
-                for shards in node_to_shards.values_mut() {
-                    if shards.len() > max_shard_per_node {
-                        // Pick the emptiest
-                        migrate_shard = Some(shards.pop().unwrap());
-                    }
-                }
-                let Some(migrate_shard) = migrate_shard else {
-                    break;
-                };
-
-                // Pick the emptiest node to migrate to
-                let mut destinations = node_to_shards
-                    .iter()
-                    .map(|(k, v)| (k, v.len()))
-                    .collect::<Vec<_>>();
-                destinations.sort_by_key(|i| i.1);
-                let (destination_node, destination_count) = *destinations.first().unwrap();
-                if destination_count + 1 > max_shard_per_node {
-                    // Even the emptiest destination doesn't have space: we're done
-                    break;
-                }
-                let destination_node = *destination_node;
-
-                node_to_shards
-                    .get_mut(&destination_node)
-                    .unwrap()
-                    .push(migrate_shard);
-
-                println!("Migrate {} -> {} ...", migrate_shard, destination_node);
-
-                storcon_client
-                    .dispatch::<TenantShardMigrateRequest, TenantShardMigrateResponse>(
-                        Method::PUT,
-                        format!("control/v1/tenant/{migrate_shard}/migrate"),
-                        Some(TenantShardMigrateRequest {
-                            tenant_shard_id: migrate_shard,
-                            node_id: destination_node,
-                        }),
-                    )
-                    .await?;
-                println!("Migrate {} -> {} OK", migrate_shard, destination_node);
-            }
-
-            // Spread the shards across the nodes
-        }
        Command::TenantDescribe { tenant_id } => {
            let describe_response = storcon_client
                .dispatch::<(), TenantDescribeResponse>(
--- a/docker-compose/README.md
+++ b/docker-compose/README.md
@@ -0,0 +1,10 @@
+
+# Example docker compose configuration
+
+The configuration in this directory is used for testing Neon docker images: it is
+not intended for deploying a usable system.  To run a development environment where
+you can experiment with a minature Neon system, use `cargo neon` rather than container images.
+
+This configuration does not start the storage controller, because the controller
+needs a way to reconfigure running computes, and no such thing exists in this setup.
+
--- a/docker-compose/compute_wrapper/shell/compute.sh
+++ b/docker-compose/compute_wrapper/shell/compute.sh
@@ -23,11 +23,10 @@ echo "Page server is ready."
 echo "Create a tenant and timeline"
 generate_id tenant_id
 PARAMS=(
-     -sb 
-     -X POST
+     -X PUT
     -H "Content-Type: application/json"
-     -d "{\"new_tenant_id\": \"${tenant_id}\"}"
-     http://pageserver:9898/v1/tenant/
+     -d "{\"mode\": \"AttachedSingle\", \"generation\": 1, \"tenant_conf\": {}}"
+     "http://pageserver:9898/v1/tenant/${tenant_id}/location_config"
 )
 result=$(curl "${PARAMS[@]}")
 echo $result | jq .
--- a/docs/rfcs/033-storage-controller-drain-and-fill.md
+++ b/docs/rfcs/033-storage-controller-drain-and-fill.md
@@ -0,0 +1,345 @@
+# Graceful Restarts of Storage Controller Managed Clusters
+
+## Summary
+This RFC describes new storage controller APIs for draining and filling tenant shards from/on pageserver nodes.
+It also covers how these new APIs should be used by an orchestrator (e.g. Ansible) in order to implement
+graceful cluster restarts.
+
+## Motivation
+
+Pageserver restarts cause read availablity downtime for tenants.
+
+For example pageserver-3 @ us-east-1 was unavailable for a randomly
+picked tenant (which requested on-demand activation) for around 30 seconds
+during the restart at 2024-04-03 16:37 UTC.
+
+Note that lots of shutdowns on loaded pageservers do not finish within the
+[10 second systemd enforced timeout](https://github.com/neondatabase/aws/blob/0a5280b383e43c063d43cbf87fa026543f6d6ad4/.github/ansible/systemd/pageserver.service#L16). This means we are shutting down without flushing ephemeral layers
+and have to reingest data in order to serve requests after restarting, potentially making first request latencies worse.
+
+This problem is not yet very acutely felt in storage controller managed pageservers since
+tenant density is much lower there. However, we are planning on eventually migrating all
+pageservers to storage controller management, so it makes sense to solve the issue proactively.
+
+## Requirements
+
+- Pageserver re-deployments cause minimal downtime for tenants
+- The storage controller exposes HTTP API hooks for draining and filling tenant shards
+from a given pageserver. Said hooks can be used by an orchestrator proces or a human operator.
+- The storage controller exposes some HTTP API to cancel draining and filling background operations.
+- Failures to drain or fill the node should not be fatal. In such cases, cluster restarts should proceed
+as usual (with downtime).
+- Progress of draining/filling is visible through metrics
+
+## Non Goals
+
+- Integration with the control plane
+- Graceful restarts for large non-HA tenants.
+
+## Impacted Components
+
+- storage controller
+- deployment orchestrator (i.e. Ansible)
+- pageserver (indirectly)
+
+## Terminology
+
+** Draining ** is the process through which all tenant shards that can be migrated from a given pageserver
+are distributed across the rest of the cluster.
+
+** Filling ** is the symmetric opposite of draining. In this process tenant shards are migrated onto a given
+pageserver until the cluster reaches a resonable, quiescent distribution of tenant shards across pageservers.
+
+** Node scheduling policies ** act as constraints to the scheduler. For instance, when a
+node is set in the `Paused` policy, no further shards will be scheduled on it.
+
+** Node ** is a pageserver. Term is used interchangeably in this RFC.
+
+** Deployment orchestrator ** is a generic term for whatever drives our deployments.
+Currently, it's an Ansible playbook.
+
+## Background
+
+### Storage Controller Basics (skip if already familiar)
+
+Fundamentally, the storage controller is a reconciler which aims to move from the observed mapping between pageservers and tenant shards to an intended mapping. Pageserver nodes and tenant shards metadata is durably persisted in a database, but note that the mapping between the two entities is not durably persisted. Instead, this mapping (*observed state*) is constructed at startup by sending `GET location_config` requests to registered pageservers.
+
+An internal scheduler maps tenant shards to pageservers while respecting certain constraints. The result of scheduling is the *intent state*. When the intent state changes, a *reconciliation* will inform pageservers about the new assigment via `PUT location_config` requests and will notify the compute via the configured hook.
+
+### Background Optimizations
+
+The storage controller performs scheduling optimizations in the background. It will
+migrate attachments to warm secondaries and replace secondaries in order to balance
+the cluster out.
+
+### Reconciliations Concurrency Limiting
+
+There's a hard limit on the number of reconciles that the storage controller
+can have in flight at any given time. To get an idea of scales, the limit is
+128 at the time of writing.
+
+## Implementation
+
+Note: this section focuses on the core functionality of the graceful restart process.
+It doesn't neccesarily describe the most efficient approach. Optimizations are described
+separately in a later section.
+
+### Overall Flow
+
+This section describes how to implement graceful restarts from the perspective
+of Ansible, the deployment orchestrator. Pageservers are already restarted sequentially.
+The orchestrator shall implement the following epilogue and prologue steps for each
+pageserver restart:
+
+#### Prologue
+
+The orchestrator shall first fetch the pageserver node id from the control plane or
+the pageserver it aims to restart directly. Next, it issues an HTTP request
+to the storage controller in order to start the drain of said pageserver node.
+All error responses are retried with a short back-off. When a 202 (Accepted)
+HTTP code is returned, the drain has started. Now the orchestrator polls the
+node status endpoint exposed by the storage controller in order to await the
+end of the drain process. When the `policy` field of the node status response
+becomes `PauseForRestart`, the drain has completed and the orchestrator can
+proceed with restarting the pageserver.
+
+The prologue is subject to an overall timeout. It will have a value in the ballpark
+of minutes. As storage controller managed pageservers become more loaded this timeout
+will likely have to increase.
+
+#### Epilogue
+
+After restarting the pageserver, the orchestrator issues an HTTP request
+to the storage controller to kick off the filling process. This API call
+may be retried for all error codes with a short backoff. This also serves
+as a synchronization primitive as the fill will be refused if the pageserver
+has not yet re-attached to the storage controller. When a 202(Accepted) HTTP
+code is returned, the fill has started. Now the orchestrator polls the node
+status endpoint exposed by the storage controller in order to await the end of
+the filling process. When the `policy` field of the node status response becomes
+`Active`, the fill has completed and the orchestrator may proceed to the next pageserver.
+
+Again, the epilogue is subject to an overall timeout. We can start off with
+using the same timeout as for the prologue, but can also consider relying on
+the storage controller's background optimizations with a shorter timeout.
+
+In the case that the deployment orchestrator times out, it attempts to cancel
+the fill. This operation shall be retried with a short back-off. If it ultimately
+fails it will require manual intervention to set the nodes scheduling policy to
+`NodeSchedulingPolicy::Active`. Not doing that is not immediately problematic,
+but it constrains the scheduler as mentioned previously.
+
+### Node Scheduling Policy State Machine
+
+The state machine below encodes the behaviours discussed above and
+the various failover situations described in a later section.
+
+Assuming no failures and/or timeouts the flow should be:
+`Active -> Draining -> PauseForRestart -> Active -> Filling -> Active`
+
+```
+                          Operator requested drain
+               +-----------------------------------------+
+               |                                         |
+       +-------+-------+                         +-------v-------+
+       |               |                         |               |
+       |     Pause     |             +----------->    Draining   +----------+
+       |               |             |           |               |          |
+       +---------------+             |           +-------+-------+          |
+                                     |                   |                  |
+                                     |                   |                  |
+                      Drain requested|                   |                  |
+                                     |                   |Drain complete    | Drain failed
+                                     |                   |                  | Cancelled/PS reattach/Storcon restart
+                                     |                   |                  |
+                             +-------+-------+           |                  |
+                             |               |           |                  |
+               +-------------+    Active     <-----------+------------------+
+               |             |               |           |
+Fill requested |             +---^---^-------+           |
+               |                 |   |                   |
+               |                 |   |                   |
+               |                 |   |                   |
+               |   Fill completed|   |                   |
+               |                 |   |PS reattach        |
+               |                 |   |after restart      |
+       +-------v-------+         |   |           +-------v-------+
+       |               |         |   |           |               |
+       |    Filling    +---------+   +-----------+PauseForRestart|
+       |               |                         |               |
+       +---------------+                         +---------------+
+```
+
+### Draining/Filling APIs
+
+The storage controller API to trigger the draining of a given node is:
+`PUT /v1/control/node/:node_id/{drain,fill}`.
+
+The following HTTP non-success return codes are used.
+All of them are safely retriable from the perspective of the storage controller.
+- 404: Requested node was not found
+- 503: Requested node is known to the storage controller, but unavailable
+- 412: Drain precondition failed: there is no other node to drain to or the node's schedulling policy forbids draining
+- 409: A {drain, fill} is already in progress. Only one such background operation
+is allowed per node.
+
+When the drain is accepted and commenced a 202 HTTP code is returned.
+
+Drains and fills shall be cancellable by the deployment orchestrator or a
+human operator via: `DELETE /v1/control/node/:node_id/{drain,fill}`. A 200
+response is returned when the cancelation is successful. Errors are retriable.
+
+### Drain Process
+
+Before accpeting a drain request the following validations is applied:
+* Ensure that the node is known the storage controller
+* Ensure that the schedulling policy is `NodeSchedulingPolicy::Active` or `NodeSchedulingPolicy::Pause`
+* Ensure that another drain or fill is not already running on the node
+* Ensure that a drain is possible (i.e. check that there is at least one
+schedulable node to drain to)
+
+After accepting the drain, the scheduling policy of the node is set to
+`NodeSchedulingPolicy::Draining` and persisted in both memory and the database.
+This disallows the optimizer from adding or removing shards from the node which
+is desirable to avoid them racing.
+
+Next, a separate Tokio task is spawned to manage the draining. For each tenant
+shard attached to the node being drained, demote the node to a secondary and
+attempt to schedule the node away. Scheduling might fail due to unsatisfiable
+constraints, but that is fine. Draining is a best effort process since it might
+not always be possible to cut over all shards.
+
+Importantly, this task manages the concurrency of issued reconciles in order to
+avoid drowning out the target pageservers and to allow other important reconciles
+to proceed.
+
+Once the triggered reconciles have finished or timed out, set the node's scheduling
+policy to `NodeSchedulingPolicy::PauseForRestart` to signal the end of the drain.
+
+A note on non HA tenants: These tenants do not have secondaries, so by the description
+above, they would not be migrated. It makes sense to skip them (especially the large ones)
+since, depending on tenant size, this might be more disruptive than the restart since the
+pageserver we've moved to do will need to on-demand download the entire working set for the tenant.
+We can consider expanding to small non-HA tenants in the future.
+
+### Fill Process
+
+Before accpeting a fill request the following validations is applied:
+* Ensure that the node is known the storage controller
+* Ensure that the schedulling policy is `NodeSchedulingPolicy::Active`.
+This is the only acceptable policy for the fill starting state. When a node re-attaches,
+it set the scheduling policy to `NodeSchedulingPolicy::Active` if it was equal to
+`NodeSchedulingPolicy::PauseForRestart` or `NodeSchedulingPolicy::Draining` (possible end states for a node drain).
+* Ensure that another drain or fill is not already running on the node
+
+After accepting the drain, the scheduling policy of the node is set to
+`NodeSchedulingPolicy::Filling` and persisted in both memory and the database.
+This disallows the optimizer from adding or removing shards from the node which
+is desirable to avoid them racing.
+
+Next, a separate Tokio task is spawned to manage the draining. For each tenant
+shard where the filled node is a secondary, promote the secondary. This is done
+until we run out of shards or the counts of attached shards become balanced across
+the cluster.
+
+Like for draining, the concurrency of spawned reconciles is limited.
+
+### Failure Modes & Handling
+
+Failures are generally handled by transition back into the `Active`
+(neutral) state. This simplifies the implementation greatly at the
+cost of adding transitions to the state machine. For example, we
+could detect the `Draining` state upon restart and proceed with a drain,
+but how should the storage controller know that's what the orchestrator
+needs still?
+
+#### Storage Controller Crash
+
+When the storage controller starts up reset the node scheduling policy
+of all nodes in states `Draining`, `Filling` or `PauseForRestart` to
+`Active`. The rationale is that when the storage controller restarts,
+we have lost context of what the deployment orchestrator wants. It also
+has the benefit of making things easier to reason about.
+
+#### Pageserver Crash During Drain
+
+The pageserver will attempt to re-attach during restart at which
+point the node scheduling policy will be set back to `Active`, thus
+reenabling the scheduler to use the node.
+
+#### Non-drained Pageserver Crash During Drain
+
+What should happen when a pageserver we are draining to crashes during the
+process. Two reasonable options are: cancel the drain and focus on the failover
+*or* do both, but prioritise failover. Since the number of concurrent reconciles
+produced by drains/fills are limited, we get the later behaviour for free.
+My suggestion is we take this approach, but the cancellation option is trivial
+to implement as well.
+
+#### Pageserver Crash During Fill
+
+The pageserver will attempt to re-attach during restart at which
+point the node scheduling policy will be set back to `Active`, thus
+reenabling the scheduler to use the node.
+
+#### Pageserver Goes unavailable During Drain/Fill
+
+The drain and fill jobs handle this by stopping early. When the pageserver
+is detected as online by storage controller heartbeats, reset its scheduling
+policy to `Active`. If a restart happens instead, see the pageserver crash
+failure mode.
+
+#### Orchestrator Drain Times Out
+
+Orchestrator will still proceed with the restart.
+When the pageserver re-attaches, the scheduling policy is set back to
+`Active`.
+
+#### Orchestrator Fill Times Out
+
+Orchestrator will attempt to cancel the fill operation. If that fails,
+the fill will continue until it quiesces and the node will be left
+in the `Filling` scheduling policy. This hinders the scheduler, but is
+otherwise harmless. A human operator can handle this by setting the scheduling
+policy to `Active`, or we can bake in a fill timeout into the storage controller.
+
+## Optimizations
+
+### Location Warmth
+
+When cutting over to a secondary, the storage controller will wait for it to
+become "warm" (i.e. download enough of the tenants data). This means that some
+reconciliations can take significantly longer than others and hold up precious
+reconciliations units. As an optimization, the drain stage can only cut over
+tenants that are already "warm". Similarly, the fill stage can prioritise the
+"warmest" tenants in the fill.
+
+Given that the number of tenants by the storage controller will be fairly low
+for the foreseable future, the first implementation could simply query the tenants
+for secondary status. This doesn't scale well with increasing tenant counts, so
+eventually we will need new pageserver API endpoints to report the sets of
+"warm" and "cold" nodes.
+
+## Alternatives Considered
+
+### Draining and Filling Purely as Scheduling Constraints
+
+At its core, the storage controller is a big background loop that detects changes
+in the environment and reacts on them. One could express draining and filling
+of nodes purely in terms of constraining the scheduler (as opposed to having
+such background tasks).
+
+While theoretically nice, I think that's harder to implement and more importantly operate and reason about.
+Consider cancellation of a drain/fill operation. We would have to update the scheduler state, create
+an entirely new schedule (intent state) and start work on applying that. It gets trickier if we wish
+to cancel the reconciliation tasks spawned by drain/fill nodes. How would we know which ones belong
+to the conceptual drain/fill? One could add labels to reconciliations, but it gets messy in my opinion.
+
+It would also mean that reconciliations themselves have side effects that persist in the database
+(persist something to the databse when the drain is done), which I'm not conceptually fond of.
+
+## Proof of Concept
+
+This RFC is accompanied by a POC which implements nearly everything mentioned here
+apart from the optimizations and some of the failure handling:
+https://github.com/neondatabase/neon/pull/7682
--- a/libs/compute_api/src/spec.rs
+++ b/libs/compute_api/src/spec.rs
@@ -96,12 +96,6 @@ pub struct ComputeSpec {
    // Stripe size for pageserver sharding, in pages
    #[serde(default)]
    pub shard_stripe_size: Option<usize>,
-
-    // When we are starting a new replica in hot standby mode,
-    // we need to know if the primary is running.
-    // This is used to determine if replica should wait for
-    // RUNNING_XACTS from primary or not.
-    pub primary_is_running: Option<bool>,
 }

 /// Feature flag to signal `compute_ctl` to enable certain experimental functionality.
--- a/libs/metrics/src/lib.rs
+++ b/libs/metrics/src/lib.rs
@@ -103,9 +103,10 @@ static MAXRSS_KB: Lazy<IntGauge> = Lazy::new(|| {
    .expect("Failed to register maxrss_kb int gauge")
 });

-pub const DISK_WRITE_SECONDS_BUCKETS: &[f64] = &[
-    0.000_050, 0.000_100, 0.000_500, 0.001, 0.003, 0.005, 0.01, 0.05, 0.1, 0.3, 0.5,
-];
+/// Most common fsync latency is 50 µs - 100 µs, but it can be much higher,
+/// especially during many concurrent disk operations.
+pub const DISK_FSYNC_SECONDS_BUCKETS: &[f64] =
+    &[0.001, 0.005, 0.01, 0.05, 0.1, 0.5, 1.0, 5.0, 10.0, 30.0];

 pub struct BuildInfo {
    pub revision: &'static str,
--- a/libs/pageserver_api/src/controller_api.rs
+++ b/libs/pageserver_api/src/controller_api.rs
@@ -11,6 +11,27 @@ use crate::{
    shard::{ShardStripeSize, TenantShardId},
 };

+#[derive(Serialize, Deserialize, Debug)]
+#[serde(deny_unknown_fields)]
+pub struct TenantCreateRequest {
+    pub new_tenant_id: TenantShardId,
+    #[serde(default)]
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub generation: Option<u32>,
+
+    // If omitted, create a single shard with TenantShardId::unsharded()
+    #[serde(default)]
+    #[serde(skip_serializing_if = "ShardParameters::is_unsharded")]
+    pub shard_parameters: ShardParameters,
+
+    #[serde(default)]
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub placement_policy: Option<PlacementPolicy>,
+
+    #[serde(flatten)]
+    pub config: TenantConfig, // as we have a flattened field, we should reject all unknown fields in it
+}
+
 #[derive(Serialize, Deserialize)]
 pub struct TenantCreateResponseShard {
    pub shard_id: TenantShardId,
@@ -280,4 +301,19 @@ mod test {
        assert_eq!(serde_json::from_str::<PlacementPolicy>(&encoded)?, v);
        Ok(())
    }
+
+    #[test]
+    fn test_reject_unknown_field() {
+        let id = TenantId::generate();
+        let create_request = serde_json::json!({
+            "new_tenant_id": id.to_string(),
+            "unknown_field": "unknown_value".to_string(),
+        });
+        let err = serde_json::from_value::<TenantCreateRequest>(create_request).unwrap_err();
+        assert!(
+            err.to_string().contains("unknown field `unknown_field`"),
+            "expect unknown field `unknown_field` error, got: {}",
+            err
+        );
+    }
 }
--- a/libs/pageserver_api/src/key.rs
+++ b/libs/pageserver_api/src/key.rs
@@ -29,7 +29,7 @@ pub const KEY_SIZE: usize = 18;
 /// See [`Key::to_i128`] for more information on the encoding.
 pub const METADATA_KEY_SIZE: usize = 16;

-/// The key prefix start range for the metadata keys. All keys with the first byte >= 0x40 is a metadata key.
+/// The key prefix start range for the metadata keys. All keys with the first byte >= 0x60 is a metadata key.
 pub const METADATA_KEY_BEGIN_PREFIX: u8 = 0x60;
 pub const METADATA_KEY_END_PREFIX: u8 = 0x7F;

@@ -160,8 +160,9 @@ impl Key {
        key
    }

-    /// Convert a 18B slice to a key. This function should not be used for metadata keys because field2 is handled differently.
-    /// Use [`Key::from_i128`] instead if you want to handle 16B keys (i.e., metadata keys).
+    /// Convert a 18B slice to a key. This function should not be used for 16B metadata keys because `field2` is handled differently.
+    /// Use [`Key::from_i128`] instead if you want to handle 16B keys (i.e., metadata keys). There are some restrictions on `field2`,
+    /// and therefore not all 18B slices are valid page server keys.
    pub fn from_slice(b: &[u8]) -> Self {
        Key {
            field1: b[0],
@@ -173,7 +174,7 @@ impl Key {
        }
    }

-    /// Convert a key to a 18B slice. This function should not be used for metadata keys because field2 is handled differently.
+    /// Convert a key to a 18B slice. This function should not be used for getting a 16B metadata key because `field2` is handled differently.
    /// Use [`Key::to_i128`] instead if you want to get a 16B key (i.e., metadata keys).
    pub fn write_to_byte_slice(&self, buf: &mut [u8]) {
        buf[0] = self.field1;
--- a/libs/pageserver_api/src/keyspace.rs
+++ b/libs/pageserver_api/src/keyspace.rs
@@ -17,6 +17,16 @@ pub struct KeySpace {
    pub ranges: Vec<Range<Key>>,
 }

+impl std::fmt::Display for KeySpace {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        write!(f, "[")?;
+        for range in &self.ranges {
+            write!(f, "{}..{},", range.start, range.end)?;
+        }
+        write!(f, "]")
+    }
+}
+
 /// A wrapper type for sparse keyspaces.
 #[derive(Clone, Debug, Default, PartialEq, Eq)]
 pub struct SparseKeySpace(pub KeySpace);
--- a/libs/pageserver_api/src/models.rs
+++ b/libs/pageserver_api/src/models.rs
@@ -9,6 +9,7 @@ use std::{
    collections::HashMap,
    io::{BufRead, Read},
    num::{NonZeroU64, NonZeroUsize},
+    str::FromStr,
    sync::atomic::AtomicUsize,
    time::{Duration, SystemTime},
 };
@@ -25,7 +26,6 @@ use utils::{
    serde_system_time,
 };

-use crate::controller_api::PlacementPolicy;
 use crate::{
    reltag::RelTag,
    shard::{ShardCount, ShardStripeSize, TenantShardId},
@@ -229,6 +229,11 @@ pub struct TimelineCreateRequest {
    pub pg_version: Option<u32>,
 }

+#[derive(Serialize, Deserialize, Clone)]
+pub struct LsnLeaseRequest {
+    pub lsn: Lsn,
+}
+
 #[derive(Serialize, Deserialize)]
 pub struct TenantShardSplitRequest {
    pub new_shard_count: u8,
@@ -271,28 +276,6 @@ impl Default for ShardParameters {
    }
 }

-#[derive(Serialize, Deserialize, Debug)]
-#[serde(deny_unknown_fields)]
-pub struct TenantCreateRequest {
-    pub new_tenant_id: TenantShardId,
-    #[serde(default)]
-    #[serde(skip_serializing_if = "Option::is_none")]
-    pub generation: Option<u32>,
-
-    // If omitted, create a single shard with TenantShardId::unsharded()
-    #[serde(default)]
-    #[serde(skip_serializing_if = "ShardParameters::is_unsharded")]
-    pub shard_parameters: ShardParameters,
-
-    // This parameter is only meaningful in requests sent to the storage controller
-    #[serde(default)]
-    #[serde(skip_serializing_if = "Option::is_none")]
-    pub placement_policy: Option<PlacementPolicy>,
-
-    #[serde(flatten)]
-    pub config: TenantConfig, // as we have a flattened field, we should reject all unknown fields in it
-}
-
 /// An alternative representation of `pageserver::tenant::TenantConf` with
 /// simpler types.
 #[derive(Serialize, Deserialize, Debug, Default, Clone, Eq, PartialEq)]
@@ -455,6 +438,51 @@ pub enum CompactionAlgorithm {
    Tiered,
 }

+#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
+pub enum ImageCompressionAlgorithm {
+    /// Disabled for writes, and never decompress during reading.
+    /// Never set this after you've enabled compression once!
+    DisabledNoDecompress,
+    // Disabled for writes, support decompressing during read path
+    Disabled,
+    /// Zstandard compression. Level 0 means and None mean the same (default level). Levels can be negative as well.
+    /// For details, see the [manual](http://facebook.github.io/zstd/zstd_manual.html).
+    Zstd {
+        level: Option<i8>,
+    },
+}
+
+impl ImageCompressionAlgorithm {
+    pub fn allow_decompression(&self) -> bool {
+        !matches!(self, ImageCompressionAlgorithm::DisabledNoDecompress)
+    }
+}
+
+impl FromStr for ImageCompressionAlgorithm {
+    type Err = anyhow::Error;
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        let mut components = s.split(['(', ')']);
+        let first = components
+            .next()
+            .ok_or_else(|| anyhow::anyhow!("empty string"))?;
+        match first {
+            "disabled-no-decompress" => Ok(ImageCompressionAlgorithm::DisabledNoDecompress),
+            "disabled" => Ok(ImageCompressionAlgorithm::Disabled),
+            "zstd" => {
+                let level = if let Some(v) = components.next() {
+                    let v: i8 = v.parse()?;
+                    Some(v)
+                } else {
+                    None
+                };
+
+                Ok(ImageCompressionAlgorithm::Zstd { level })
+            }
+            _ => anyhow::bail!("invalid specifier '{first}'"),
+        }
+    }
+}
+
 #[derive(Eq, PartialEq, Debug, Clone, Serialize, Deserialize)]
 pub struct CompactionAlgorithmSettings {
    pub kind: CompactionAlgorithm,
@@ -547,10 +575,6 @@ pub struct LocationConfigListResponse {
    pub tenant_shards: Vec<(TenantShardId, Option<LocationConfig>)>,
 }

-#[derive(Serialize, Deserialize)]
-#[serde(transparent)]
-pub struct TenantCreateResponse(pub TenantId);
-
 #[derive(Serialize)]
 pub struct StatusResponse {
    pub id: NodeId,
@@ -607,31 +631,6 @@ impl TenantConfigRequest {
    }
 }

-#[derive(Debug, Deserialize)]
-pub struct TenantAttachRequest {
-    #[serde(default)]
-    pub config: TenantAttachConfig,
-    #[serde(default)]
-    pub generation: Option<u32>,
-}
-
-/// Newtype to enforce deny_unknown_fields on TenantConfig for
-/// its usage inside `TenantAttachRequest`.
-#[derive(Debug, Serialize, Deserialize, Default)]
-#[serde(deny_unknown_fields)]
-pub struct TenantAttachConfig {
-    #[serde(flatten)]
-    allowing_unknown_fields: TenantConfig,
-}
-
-impl std::ops::Deref for TenantAttachConfig {
-    type Target = TenantConfig;
-
-    fn deref(&self) -> &Self::Target {
-        &self.allowing_unknown_fields
-    }
-}
-
 /// See [`TenantState::attachment_status`] and the OpenAPI docs for context.
 #[derive(Serialize, Deserialize, Clone)]
 #[serde(tag = "slug", content = "data", rename_all = "snake_case")]
@@ -650,8 +649,7 @@ pub struct TenantInfo {
    /// If a layer is present in both local FS and S3, it counts only once.
    pub current_physical_size: Option<u64>, // physical size is only included in `tenant_status` endpoint
    pub attachment_status: TenantAttachmentStatus,
-    #[serde(skip_serializing_if = "Option::is_none")]
-    pub generation: Option<u32>,
+    pub generation: u32,
 }

 #[derive(Serialize, Deserialize, Clone)]
@@ -696,6 +694,16 @@ pub struct TimelineInfo {
    pub current_physical_size: Option<u64>, // is None when timeline is Unloaded
    pub current_logical_size_non_incremental: Option<u64>,

+    /// How many bytes of WAL are within this branch's pitr_interval.  If the pitr_interval goes
+    /// beyond the branch's branch point, we only count up to the branch point.
+    pub pitr_history_size: u64,
+
+    /// Whether this branch's branch point is within its ancestor's PITR interval (i.e. any
+    /// ancestor data used by this branch would have been retained anyway).  If this is false, then
+    /// this branch may be imposing a cost on the ancestor by causing it to retain layers that it would
+    /// otherwise be able to GC.
+    pub within_ancestor_pitr: bool,
+
    pub timeline_dir_layer_file_size_sum: Option<u64>,

    pub wal_source_connstr: Option<String>,
@@ -1478,7 +1486,7 @@ mod tests {
            state: TenantState::Active,
            current_physical_size: Some(42),
            attachment_status: TenantAttachmentStatus::Attached,
-            generation: None,
+            generation: 1,
        };
        let expected_active = json!({
            "id": original_active.id.to_string(),
@@ -1488,7 +1496,8 @@ mod tests {
            "current_physical_size": 42,
            "attachment_status": {
                "slug":"attached",
-            }
+            },
+            "generation" : 1
        });

        let original_broken = TenantInfo {
@@ -1499,7 +1508,7 @@ mod tests {
            },
            current_physical_size: Some(42),
            attachment_status: TenantAttachmentStatus::Attached,
-            generation: None,
+            generation: 1,
        };
        let expected_broken = json!({
            "id": original_broken.id.to_string(),
@@ -1513,7 +1522,8 @@ mod tests {
            "current_physical_size": 42,
            "attachment_status": {
                "slug":"attached",
-            }
+            },
+            "generation" : 1
        });

        assert_eq!(
@@ -1531,18 +1541,6 @@ mod tests {

    #[test]
    fn test_reject_unknown_field() {
-        let id = TenantId::generate();
-        let create_request = json!({
-            "new_tenant_id": id.to_string(),
-            "unknown_field": "unknown_value".to_string(),
-        });
-        let err = serde_json::from_value::<TenantCreateRequest>(create_request).unwrap_err();
-        assert!(
-            err.to_string().contains("unknown field `unknown_field`"),
-            "expect unknown field `unknown_field` error, got: {}",
-            err
-        );
-
        let id = TenantId::generate();
        let config_request = json!({
            "tenant_id": id.to_string(),
@@ -1554,18 +1552,6 @@ mod tests {
            "expect unknown field `unknown_field` error, got: {}",
            err
        );
-
-        let attach_request = json!({
-            "config": {
-                "unknown_field": "unknown_value".to_string(),
-            },
-        });
-        let err = serde_json::from_value::<TenantAttachRequest>(attach_request).unwrap_err();
-        assert!(
-            err.to_string().contains("unknown field `unknown_field`"),
-            "expect unknown field `unknown_field` error, got: {}",
-            err
-        );
    }

    #[test]
@@ -1689,4 +1675,29 @@ mod tests {
            AuxFilePolicy::CrossValidation
        );
    }
+
+    #[test]
+    fn test_image_compression_algorithm_parsing() {
+        use ImageCompressionAlgorithm::*;
+        assert_eq!(
+            ImageCompressionAlgorithm::from_str("disabled").unwrap(),
+            Disabled
+        );
+        assert_eq!(
+            ImageCompressionAlgorithm::from_str("disabled-no-decompress").unwrap(),
+            DisabledNoDecompress
+        );
+        assert_eq!(
+            ImageCompressionAlgorithm::from_str("zstd").unwrap(),
+            Zstd { level: None }
+        );
+        assert_eq!(
+            ImageCompressionAlgorithm::from_str("zstd(18)").unwrap(),
+            Zstd { level: Some(18) }
+        );
+        assert_eq!(
+            ImageCompressionAlgorithm::from_str("zstd(-3)").unwrap(),
+            Zstd { level: Some(-3) }
+        );
+    }
 }
--- a/libs/postgres_connection/src/lib.rs
+++ b/libs/postgres_connection/src/lib.rs
@@ -144,20 +144,7 @@ impl PgConnectionConfig {
            // implement and this function is hardly a bottleneck. The function is only called around
            // establishing a new connection.
            #[allow(unstable_name_collisions)]
-            config.options(
-                &self
-                    .options
-                    .iter()
-                    .map(|s| {
-                        if s.contains(['\\', ' ']) {
-                            Cow::Owned(s.replace('\\', "\\\\").replace(' ', "\\ "))
-                        } else {
-                            Cow::Borrowed(s.as_str())
-                        }
-                    })
-                    .intersperse(Cow::Borrowed(" ")) // TODO: use impl from std once it's stabilized
-                    .collect::<String>(),
-            );
+            config.options(&encode_options(&self.options));
        }
        config
    }
@@ -178,6 +165,21 @@ impl PgConnectionConfig {
    }
 }

+#[allow(unstable_name_collisions)]
+fn encode_options(options: &[String]) -> String {
+    options
+        .iter()
+        .map(|s| {
+            if s.contains(['\\', ' ']) {
+                Cow::Owned(s.replace('\\', "\\\\").replace(' ', "\\ "))
+            } else {
+                Cow::Borrowed(s.as_str())
+            }
+        })
+        .intersperse(Cow::Borrowed(" ")) // TODO: use impl from std once it's stabilized
+        .collect::<String>()
+}
+
 impl fmt::Display for PgConnectionConfig {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        // The password is intentionally hidden and not part of this display string.
@@ -206,7 +208,7 @@ impl fmt::Debug for PgConnectionConfig {

 #[cfg(test)]
 mod tests_pg_connection_config {
-    use crate::PgConnectionConfig;
+    use crate::{encode_options, PgConnectionConfig};
    use once_cell::sync::Lazy;
    use url::Host;

@@ -255,18 +257,12 @@ mod tests_pg_connection_config {

    #[test]
    fn test_with_options() {
-        let cfg = PgConnectionConfig::new_host_port(STUB_HOST.clone(), 123).extend_options([
-            "hello",
-            "world",
-            "with space",
-            "and \\ backslashes",
+        let options = encode_options(&[
+            "hello".to_owned(),
+            "world".to_owned(),
+            "with space".to_owned(),
+            "and \\ backslashes".to_owned(),
        ]);
-        assert_eq!(cfg.host(), &*STUB_HOST);
-        assert_eq!(cfg.port(), 123);
-        assert_eq!(cfg.raw_address(), "stub.host.example:123");
-        assert_eq!(
-            cfg.to_tokio_postgres_config().get_options(),
-            Some("hello world with\\ space and\\ \\\\\\ backslashes")
-        );
+        assert_eq!(options, "hello world with\\ space and\\ \\\\\\ backslashes");
    }
 }
--- a/libs/postgres_ffi/src/xlog_utils.rs
+++ b/libs/postgres_ffi/src/xlog_utils.rs
@@ -356,6 +356,28 @@ impl CheckPoint {
        }
        false
    }
+
+    /// Advance next multi-XID/offset to those given in arguments.
+    ///
+    /// It's important that this handles wraparound correctly. This should match the
+    /// MultiXactAdvanceNextMXact() logic in PostgreSQL's xlog_redo() function.
+    ///
+    /// Returns 'true' if the Checkpoint was updated.
+    pub fn update_next_multixid(&mut self, multi_xid: u32, multi_offset: u32) -> bool {
+        let mut modified = false;
+
+        if multi_xid.wrapping_sub(self.nextMulti) as i32 > 0 {
+            self.nextMulti = multi_xid;
+            modified = true;
+        }
+
+        if multi_offset.wrapping_sub(self.nextMultiOffset) as i32 > 0 {
+            self.nextMultiOffset = multi_offset;
+            modified = true;
+        }
+
+        modified
+    }
 }

 /// Generate new, empty WAL segment, with correct block headers at the first
--- a/libs/postgres_ffi/wal_craft/src/xlog_utils_test.rs
+++ b/libs/postgres_ffi/wal_craft/src/xlog_utils_test.rs
@@ -202,6 +202,53 @@ pub fn test_update_next_xid() {
    assert_eq!(checkpoint.nextXid.value, 2048);
 }

+#[test]
+pub fn test_update_next_multixid() {
+    let checkpoint_buf = [0u8; std::mem::size_of::<CheckPoint>()];
+    let mut checkpoint = CheckPoint::decode(&checkpoint_buf).unwrap();
+
+    // simple case
+    checkpoint.nextMulti = 20;
+    checkpoint.nextMultiOffset = 20;
+    checkpoint.update_next_multixid(1000, 2000);
+    assert_eq!(checkpoint.nextMulti, 1000);
+    assert_eq!(checkpoint.nextMultiOffset, 2000);
+
+    // No change
+    checkpoint.update_next_multixid(500, 900);
+    assert_eq!(checkpoint.nextMulti, 1000);
+    assert_eq!(checkpoint.nextMultiOffset, 2000);
+
+    // Close to wraparound, but not wrapped around yet
+    checkpoint.nextMulti = 0xffff0000;
+    checkpoint.nextMultiOffset = 0xfffe0000;
+    checkpoint.update_next_multixid(0xffff00ff, 0xfffe00ff);
+    assert_eq!(checkpoint.nextMulti, 0xffff00ff);
+    assert_eq!(checkpoint.nextMultiOffset, 0xfffe00ff);
+
+    // Wraparound
+    checkpoint.update_next_multixid(1, 900);
+    assert_eq!(checkpoint.nextMulti, 1);
+    assert_eq!(checkpoint.nextMultiOffset, 900);
+
+    // Wraparound nextMulti to 0.
+    //
+    // It's a bit surprising that nextMulti can be 0, because that's a special value
+    // (InvalidMultiXactId). However, that's how Postgres does it at multi-xid wraparound:
+    // nextMulti wraps around to 0, but then when the next multi-xid is assigned, it skips
+    // the 0 and the next multi-xid actually assigned is 1.
+    checkpoint.nextMulti = 0xffff0000;
+    checkpoint.nextMultiOffset = 0xfffe0000;
+    checkpoint.update_next_multixid(0, 0xfffe00ff);
+    assert_eq!(checkpoint.nextMulti, 0);
+    assert_eq!(checkpoint.nextMultiOffset, 0xfffe00ff);
+
+    // Wraparound nextMultiOffset to 0
+    checkpoint.update_next_multixid(0, 0);
+    assert_eq!(checkpoint.nextMulti, 0);
+    assert_eq!(checkpoint.nextMultiOffset, 0);
+}
+
 #[test]
 pub fn test_encode_logical_message() {
    let expected = [
--- a/libs/remote_storage/Cargo.toml
+++ b/libs/remote_storage/Cargo.toml
@@ -14,8 +14,9 @@ aws-config.workspace = true
 aws-sdk-s3.workspace = true
 aws-credential-types.workspace = true
 bytes.workspace = true
-camino.workspace = true
+camino = { workspace = true, features = ["serde1"] }
 humantime.workspace = true
+humantime-serde.workspace = true
 hyper = { workspace = true, features = ["stream"] }
 futures.workspace = true
 rand.workspace = true
--- a/libs/remote_storage/src/azure_blob.rs
+++ b/libs/remote_storage/src/azure_blob.rs
@@ -34,7 +34,7 @@ use utils::backoff;

 use crate::metrics::{start_measuring_requests, AttemptOutcome, RequestKind};
 use crate::{
-    error::Cancelled, AzureConfig, ConcurrencyLimiter, Download, DownloadError, Listing,
+    config::AzureConfig, error::Cancelled, ConcurrencyLimiter, Download, DownloadError, Listing,
    ListingMode, RemotePath, RemoteStorage, StorageMetadata, TimeTravelError, TimeoutOrCancel,
 };

--- a/libs/remote_storage/src/config.rs
+++ b/libs/remote_storage/src/config.rs
@@ -0,0 +1,264 @@
+use std::{fmt::Debug, num::NonZeroUsize, str::FromStr, time::Duration};
+
+use aws_sdk_s3::types::StorageClass;
+use camino::Utf8PathBuf;
+
+use serde::{Deserialize, Serialize};
+
+use crate::{
+    DEFAULT_MAX_KEYS_PER_LIST_RESPONSE, DEFAULT_REMOTE_STORAGE_AZURE_CONCURRENCY_LIMIT,
+    DEFAULT_REMOTE_STORAGE_S3_CONCURRENCY_LIMIT,
+};
+
+/// External backup storage configuration, enough for creating a client for that storage.
+#[derive(Debug, Clone, PartialEq, Eq, Deserialize, Serialize)]
+pub struct RemoteStorageConfig {
+    /// The storage connection configuration.
+    #[serde(flatten)]
+    pub storage: RemoteStorageKind,
+    /// A common timeout enforced for all requests after concurrency limiter permit has been
+    /// acquired.
+    #[serde(
+        with = "humantime_serde",
+        default = "default_timeout",
+        skip_serializing_if = "is_default_timeout"
+    )]
+    pub timeout: Duration,
+}
+
+fn default_timeout() -> Duration {
+    RemoteStorageConfig::DEFAULT_TIMEOUT
+}
+
+fn is_default_timeout(d: &Duration) -> bool {
+    *d == RemoteStorageConfig::DEFAULT_TIMEOUT
+}
+
+/// A kind of a remote storage to connect to, with its connection configuration.
+#[derive(Debug, Clone, PartialEq, Eq, Deserialize, Serialize)]
+#[serde(untagged)]
+pub enum RemoteStorageKind {
+    /// Storage based on local file system.
+    /// Specify a root folder to place all stored files into.
+    LocalFs { local_path: Utf8PathBuf },
+    /// AWS S3 based storage, storing all files in the S3 bucket
+    /// specified by the config
+    AwsS3(S3Config),
+    /// Azure Blob based storage, storing all files in the container
+    /// specified by the config
+    AzureContainer(AzureConfig),
+}
+
+/// AWS S3 bucket coordinates and access credentials to manage the bucket contents (read and write).
+#[derive(Clone, PartialEq, Eq, Deserialize, Serialize)]
+pub struct S3Config {
+    /// Name of the bucket to connect to.
+    pub bucket_name: String,
+    /// The region where the bucket is located at.
+    pub bucket_region: String,
+    /// A "subfolder" in the bucket, to use the same bucket separately by multiple remote storage users at once.
+    pub prefix_in_bucket: Option<String>,
+    /// A base URL to send S3 requests to.
+    /// By default, the endpoint is derived from a region name, assuming it's
+    /// an AWS S3 region name, erroring on wrong region name.
+    /// Endpoint provides a way to support other S3 flavors and their regions.
+    ///
+    /// Example: `http://127.0.0.1:5000`
+    pub endpoint: Option<String>,
+    /// AWS S3 has various limits on its API calls, we need not to exceed those.
+    /// See [`DEFAULT_REMOTE_STORAGE_S3_CONCURRENCY_LIMIT`] for more details.
+    #[serde(default = "default_remote_storage_s3_concurrency_limit")]
+    pub concurrency_limit: NonZeroUsize,
+    #[serde(default = "default_max_keys_per_list_response")]
+    pub max_keys_per_list_response: Option<i32>,
+    #[serde(
+        deserialize_with = "deserialize_storage_class",
+        serialize_with = "serialize_storage_class",
+        default
+    )]
+    pub upload_storage_class: Option<StorageClass>,
+}
+
+fn default_remote_storage_s3_concurrency_limit() -> NonZeroUsize {
+    DEFAULT_REMOTE_STORAGE_S3_CONCURRENCY_LIMIT
+        .try_into()
+        .unwrap()
+}
+
+fn default_max_keys_per_list_response() -> Option<i32> {
+    DEFAULT_MAX_KEYS_PER_LIST_RESPONSE
+}
+
+impl Debug for S3Config {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        f.debug_struct("S3Config")
+            .field("bucket_name", &self.bucket_name)
+            .field("bucket_region", &self.bucket_region)
+            .field("prefix_in_bucket", &self.prefix_in_bucket)
+            .field("concurrency_limit", &self.concurrency_limit)
+            .field(
+                "max_keys_per_list_response",
+                &self.max_keys_per_list_response,
+            )
+            .finish()
+    }
+}
+
+/// Azure  bucket coordinates and access credentials to manage the bucket contents (read and write).
+#[derive(Clone, PartialEq, Eq, Serialize, Deserialize)]
+pub struct AzureConfig {
+    /// Name of the container to connect to.
+    pub container_name: String,
+    /// Name of the storage account the container is inside of
+    pub storage_account: Option<String>,
+    /// The region where the bucket is located at.
+    pub container_region: String,
+    /// A "subfolder" in the container, to use the same container separately by multiple remote storage users at once.
+    pub prefix_in_container: Option<String>,
+    /// Azure has various limits on its API calls, we need not to exceed those.
+    /// See [`DEFAULT_REMOTE_STORAGE_AZURE_CONCURRENCY_LIMIT`] for more details.
+    #[serde(default = "default_remote_storage_azure_concurrency_limit")]
+    pub concurrency_limit: NonZeroUsize,
+    #[serde(default = "default_max_keys_per_list_response")]
+    pub max_keys_per_list_response: Option<i32>,
+}
+
+fn default_remote_storage_azure_concurrency_limit() -> NonZeroUsize {
+    NonZeroUsize::new(DEFAULT_REMOTE_STORAGE_AZURE_CONCURRENCY_LIMIT).unwrap()
+}
+
+impl Debug for AzureConfig {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        f.debug_struct("AzureConfig")
+            .field("bucket_name", &self.container_name)
+            .field("storage_account", &self.storage_account)
+            .field("bucket_region", &self.container_region)
+            .field("prefix_in_container", &self.prefix_in_container)
+            .field("concurrency_limit", &self.concurrency_limit)
+            .field(
+                "max_keys_per_list_response",
+                &self.max_keys_per_list_response,
+            )
+            .finish()
+    }
+}
+
+fn deserialize_storage_class<'de, D: serde::Deserializer<'de>>(
+    deserializer: D,
+) -> Result<Option<StorageClass>, D::Error> {
+    Option::<String>::deserialize(deserializer).and_then(|s| {
+        if let Some(s) = s {
+            use serde::de::Error;
+            let storage_class = StorageClass::from_str(&s).expect("infallible");
+            #[allow(deprecated)]
+            if matches!(storage_class, StorageClass::Unknown(_)) {
+                return Err(D::Error::custom(format!(
+                    "Specified storage class unknown to SDK: '{s}'. Allowed values: {:?}",
+                    StorageClass::values()
+                )));
+            }
+            Ok(Some(storage_class))
+        } else {
+            Ok(None)
+        }
+    })
+}
+
+fn serialize_storage_class<S: serde::Serializer>(
+    val: &Option<StorageClass>,
+    serializer: S,
+) -> Result<S::Ok, S::Error> {
+    let val = val.as_ref().map(StorageClass::as_str);
+    Option::<&str>::serialize(&val, serializer)
+}
+
+impl RemoteStorageConfig {
+    pub const DEFAULT_TIMEOUT: Duration = std::time::Duration::from_secs(120);
+
+    pub fn from_toml(toml: &toml_edit::Item) -> anyhow::Result<RemoteStorageConfig> {
+        Ok(utils::toml_edit_ext::deserialize_item(toml)?)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    fn parse(input: &str) -> anyhow::Result<RemoteStorageConfig> {
+        let toml = input.parse::<toml_edit::Document>().unwrap();
+        RemoteStorageConfig::from_toml(toml.as_item())
+    }
+
+    #[test]
+    fn parse_localfs_config_with_timeout() {
+        let input = "local_path = '.'
+timeout = '5s'";
+
+        let config = parse(input).unwrap();
+
+        assert_eq!(
+            config,
+            RemoteStorageConfig {
+                storage: RemoteStorageKind::LocalFs {
+                    local_path: Utf8PathBuf::from(".")
+                },
+                timeout: Duration::from_secs(5)
+            }
+        );
+    }
+
+    #[test]
+    fn test_s3_parsing() {
+        let toml = "\
+    bucket_name = 'foo-bar'
+    bucket_region = 'eu-central-1'
+    upload_storage_class = 'INTELLIGENT_TIERING'
+    timeout = '7s'
+    ";
+
+        let config = parse(toml).unwrap();
+
+        assert_eq!(
+            config,
+            RemoteStorageConfig {
+                storage: RemoteStorageKind::AwsS3(S3Config {
+                    bucket_name: "foo-bar".into(),
+                    bucket_region: "eu-central-1".into(),
+                    prefix_in_bucket: None,
+                    endpoint: None,
+                    concurrency_limit: default_remote_storage_s3_concurrency_limit(),
+                    max_keys_per_list_response: DEFAULT_MAX_KEYS_PER_LIST_RESPONSE,
+                    upload_storage_class: Some(StorageClass::IntelligentTiering),
+                }),
+                timeout: Duration::from_secs(7)
+            }
+        );
+    }
+
+    #[test]
+    fn test_azure_parsing() {
+        let toml = "\
+    container_name = 'foo-bar'
+    container_region = 'westeurope'
+    upload_storage_class = 'INTELLIGENT_TIERING'
+    timeout = '7s'
+    ";
+
+        let config = parse(toml).unwrap();
+
+        assert_eq!(
+            config,
+            RemoteStorageConfig {
+                storage: RemoteStorageKind::AzureContainer(AzureConfig {
+                    container_name: "foo-bar".into(),
+                    storage_account: None,
+                    container_region: "westeurope".into(),
+                    prefix_in_container: None,
+                    concurrency_limit: default_remote_storage_azure_concurrency_limit(),
+                    max_keys_per_list_response: DEFAULT_MAX_KEYS_PER_LIST_RESPONSE,
+                }),
+                timeout: Duration::from_secs(7)
+            }
+        );
+    }
+}
--- a/libs/remote_storage/src/lib.rs
+++ b/libs/remote_storage/src/lib.rs
@@ -10,6 +10,7 @@
 #![deny(clippy::undocumented_unsafe_blocks)]

 mod azure_blob;
+mod config;
 mod error;
 mod local_fs;
 mod metrics;
@@ -18,17 +19,10 @@ mod simulate_failures;
 mod support;

 use std::{
-    collections::HashMap,
-    fmt::Debug,
-    num::{NonZeroU32, NonZeroUsize},
-    pin::Pin,
-    str::FromStr,
-    sync::Arc,
-    time::{Duration, SystemTime},
+    collections::HashMap, fmt::Debug, num::NonZeroU32, pin::Pin, sync::Arc, time::SystemTime,
 };

-use anyhow::{bail, Context};
-use aws_sdk_s3::types::StorageClass;
+use anyhow::Context;
 use camino::{Utf8Path, Utf8PathBuf};

 use bytes::Bytes;
@@ -36,7 +30,6 @@ use futures::stream::Stream;
 use serde::{Deserialize, Serialize};
 use tokio::sync::Semaphore;
 use tokio_util::sync::CancellationToken;
-use toml_edit::Item;
 use tracing::info;

 pub use self::{
@@ -45,6 +38,8 @@ pub use self::{
 };
 use s3_bucket::RequestKind;

+pub use crate::config::{AzureConfig, RemoteStorageConfig, RemoteStorageKind, S3Config};
+
 /// Azure SDK's ETag type is a simple String wrapper: we use this internally instead of repeating it here.
 pub use azure_core::Etag;

@@ -451,7 +446,7 @@ impl GenericRemoteStorage {
    pub fn from_config(storage_config: &RemoteStorageConfig) -> anyhow::Result<Self> {
        let timeout = storage_config.timeout;
        Ok(match &storage_config.storage {
-            RemoteStorageKind::LocalFs(path) => {
+            RemoteStorageKind::LocalFs { local_path: path } => {
                info!("Using fs root '{path}' as a remote storage");
                Self::LocalFs(LocalFs::new(path.clone(), timeout)?)
            }
@@ -526,262 +521,6 @@ impl<const N: usize> From<[(&str, &str); N]> for StorageMetadata {
    }
 }

-/// External backup storage configuration, enough for creating a client for that storage.
-#[derive(Debug, Clone, PartialEq, Eq)]
-pub struct RemoteStorageConfig {
-    /// The storage connection configuration.
-    pub storage: RemoteStorageKind,
-    /// A common timeout enforced for all requests after concurrency limiter permit has been
-    /// acquired.
-    pub timeout: Duration,
-}
-
-/// A kind of a remote storage to connect to, with its connection configuration.
-#[derive(Debug, Clone, PartialEq, Eq)]
-pub enum RemoteStorageKind {
-    /// Storage based on local file system.
-    /// Specify a root folder to place all stored files into.
-    LocalFs(Utf8PathBuf),
-    /// AWS S3 based storage, storing all files in the S3 bucket
-    /// specified by the config
-    AwsS3(S3Config),
-    /// Azure Blob based storage, storing all files in the container
-    /// specified by the config
-    AzureContainer(AzureConfig),
-}
-
-/// AWS S3 bucket coordinates and access credentials to manage the bucket contents (read and write).
-#[derive(Clone, PartialEq, Eq)]
-pub struct S3Config {
-    /// Name of the bucket to connect to.
-    pub bucket_name: String,
-    /// The region where the bucket is located at.
-    pub bucket_region: String,
-    /// A "subfolder" in the bucket, to use the same bucket separately by multiple remote storage users at once.
-    pub prefix_in_bucket: Option<String>,
-    /// A base URL to send S3 requests to.
-    /// By default, the endpoint is derived from a region name, assuming it's
-    /// an AWS S3 region name, erroring on wrong region name.
-    /// Endpoint provides a way to support other S3 flavors and their regions.
-    ///
-    /// Example: `http://127.0.0.1:5000`
-    pub endpoint: Option<String>,
-    /// AWS S3 has various limits on its API calls, we need not to exceed those.
-    /// See [`DEFAULT_REMOTE_STORAGE_S3_CONCURRENCY_LIMIT`] for more details.
-    pub concurrency_limit: NonZeroUsize,
-    pub max_keys_per_list_response: Option<i32>,
-    pub upload_storage_class: Option<StorageClass>,
-}
-
-impl Debug for S3Config {
-    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-        f.debug_struct("S3Config")
-            .field("bucket_name", &self.bucket_name)
-            .field("bucket_region", &self.bucket_region)
-            .field("prefix_in_bucket", &self.prefix_in_bucket)
-            .field("concurrency_limit", &self.concurrency_limit)
-            .field(
-                "max_keys_per_list_response",
-                &self.max_keys_per_list_response,
-            )
-            .finish()
-    }
-}
-
-/// Azure  bucket coordinates and access credentials to manage the bucket contents (read and write).
-#[derive(Clone, PartialEq, Eq)]
-pub struct AzureConfig {
-    /// Name of the container to connect to.
-    pub container_name: String,
-    /// Name of the storage account the container is inside of
-    pub storage_account: Option<String>,
-    /// The region where the bucket is located at.
-    pub container_region: String,
-    /// A "subfolder" in the container, to use the same container separately by multiple remote storage users at once.
-    pub prefix_in_container: Option<String>,
-    /// Azure has various limits on its API calls, we need not to exceed those.
-    /// See [`DEFAULT_REMOTE_STORAGE_AZURE_CONCURRENCY_LIMIT`] for more details.
-    pub concurrency_limit: NonZeroUsize,
-    pub max_keys_per_list_response: Option<i32>,
-}
-
-impl Debug for AzureConfig {
-    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-        f.debug_struct("AzureConfig")
-            .field("bucket_name", &self.container_name)
-            .field("storage_account", &self.storage_account)
-            .field("bucket_region", &self.container_region)
-            .field("prefix_in_container", &self.prefix_in_container)
-            .field("concurrency_limit", &self.concurrency_limit)
-            .field(
-                "max_keys_per_list_response",
-                &self.max_keys_per_list_response,
-            )
-            .finish()
-    }
-}
-
-impl RemoteStorageConfig {
-    pub const DEFAULT_TIMEOUT: Duration = std::time::Duration::from_secs(120);
-
-    pub fn from_toml(toml: &toml_edit::Item) -> anyhow::Result<Option<RemoteStorageConfig>> {
-        let local_path = toml.get("local_path");
-        let bucket_name = toml.get("bucket_name");
-        let bucket_region = toml.get("bucket_region");
-        let container_name = toml.get("container_name");
-        let container_region = toml.get("container_region");
-
-        let use_azure = container_name.is_some() && container_region.is_some();
-
-        let default_concurrency_limit = if use_azure {
-            DEFAULT_REMOTE_STORAGE_AZURE_CONCURRENCY_LIMIT
-        } else {
-            DEFAULT_REMOTE_STORAGE_S3_CONCURRENCY_LIMIT
-        };
-        let concurrency_limit = NonZeroUsize::new(
-            parse_optional_integer("concurrency_limit", toml)?.unwrap_or(default_concurrency_limit),
-        )
-        .context("Failed to parse 'concurrency_limit' as a positive integer")?;
-
-        let max_keys_per_list_response =
-            parse_optional_integer::<i32, _>("max_keys_per_list_response", toml)
-                .context("Failed to parse 'max_keys_per_list_response' as a positive integer")?
-                .or(DEFAULT_MAX_KEYS_PER_LIST_RESPONSE);
-
-        let endpoint = toml
-            .get("endpoint")
-            .map(|endpoint| parse_toml_string("endpoint", endpoint))
-            .transpose()?;
-
-        let timeout = toml
-            .get("timeout")
-            .map(|timeout| {
-                timeout
-                    .as_str()
-                    .ok_or_else(|| anyhow::Error::msg("timeout was not a string"))
-            })
-            .transpose()
-            .and_then(|timeout| {
-                timeout
-                    .map(humantime::parse_duration)
-                    .transpose()
-                    .map_err(anyhow::Error::new)
-            })
-            .context("parse timeout")?
-            .unwrap_or(Self::DEFAULT_TIMEOUT);
-
-        if timeout < Duration::from_secs(1) {
-            bail!("timeout was specified as {timeout:?} which is too low");
-        }
-
-        let storage = match (
-            local_path,
-            bucket_name,
-            bucket_region,
-            container_name,
-            container_region,
-        ) {
-            // no 'local_path' nor 'bucket_name' options are provided, consider this remote storage disabled
-            (None, None, None, None, None) => return Ok(None),
-            (_, Some(_), None, ..) => {
-                bail!("'bucket_region' option is mandatory if 'bucket_name' is given ")
-            }
-            (_, None, Some(_), ..) => {
-                bail!("'bucket_name' option is mandatory if 'bucket_region' is given ")
-            }
-            (None, Some(bucket_name), Some(bucket_region), ..) => {
-                RemoteStorageKind::AwsS3(S3Config {
-                    bucket_name: parse_toml_string("bucket_name", bucket_name)?,
-                    bucket_region: parse_toml_string("bucket_region", bucket_region)?,
-                    prefix_in_bucket: toml
-                        .get("prefix_in_bucket")
-                        .map(|prefix_in_bucket| {
-                            parse_toml_string("prefix_in_bucket", prefix_in_bucket)
-                        })
-                        .transpose()?,
-                    endpoint,
-                    concurrency_limit,
-                    max_keys_per_list_response,
-                    upload_storage_class: toml
-                        .get("upload_storage_class")
-                        .map(|prefix_in_bucket| -> anyhow::Result<_> {
-                            let s = parse_toml_string("upload_storage_class", prefix_in_bucket)?;
-                            let storage_class = StorageClass::from_str(&s).expect("infallible");
-                            #[allow(deprecated)]
-                            if matches!(storage_class, StorageClass::Unknown(_)) {
-                                bail!("Specified storage class unknown to SDK: '{s}'. Allowed values: {:?}", StorageClass::values());
-                            }
-                            Ok(storage_class)
-                        })
-                        .transpose()?,
-                })
-            }
-            (_, _, _, Some(_), None) => {
-                bail!("'container_name' option is mandatory if 'container_region' is given ")
-            }
-            (_, _, _, None, Some(_)) => {
-                bail!("'container_name' option is mandatory if 'container_region' is given ")
-            }
-            (None, None, None, Some(container_name), Some(container_region)) => {
-                RemoteStorageKind::AzureContainer(AzureConfig {
-                    container_name: parse_toml_string("container_name", container_name)?,
-                    storage_account: toml
-                        .get("storage_account")
-                        .map(|storage_account| {
-                            parse_toml_string("storage_account", storage_account)
-                        })
-                        .transpose()?,
-                    container_region: parse_toml_string("container_region", container_region)?,
-                    prefix_in_container: toml
-                        .get("prefix_in_container")
-                        .map(|prefix_in_container| {
-                            parse_toml_string("prefix_in_container", prefix_in_container)
-                        })
-                        .transpose()?,
-                    concurrency_limit,
-                    max_keys_per_list_response,
-                })
-            }
-            (Some(local_path), None, None, None, None) => RemoteStorageKind::LocalFs(
-                Utf8PathBuf::from(parse_toml_string("local_path", local_path)?),
-            ),
-            (Some(_), Some(_), ..) => {
-                bail!("'local_path' and 'bucket_name' are mutually exclusive")
-            }
-            (Some(_), _, _, Some(_), Some(_)) => {
-                bail!("local_path and 'container_name' are mutually exclusive")
-            }
-        };
-
-        Ok(Some(RemoteStorageConfig { storage, timeout }))
-    }
-}
-
-// Helper functions to parse a toml Item
-fn parse_optional_integer<I, E>(name: &str, item: &toml_edit::Item) -> anyhow::Result<Option<I>>
-where
-    I: TryFrom<i64, Error = E>,
-    E: std::error::Error + Send + Sync + 'static,
-{
-    let toml_integer = match item.get(name) {
-        Some(item) => item
-            .as_integer()
-            .with_context(|| format!("configure option {name} is not an integer"))?,
-        None => return Ok(None),
-    };
-
-    I::try_from(toml_integer)
-        .map(Some)
-        .with_context(|| format!("configure option {name} is too large"))
-}
-
-fn parse_toml_string(name: &str, item: &Item) -> anyhow::Result<String> {
-    let s = item
-        .as_str()
-        .with_context(|| format!("configure option {name} is not a string"))?;
-    Ok(s.to_string())
-}
-
 struct ConcurrencyLimiter {
    // Every request to S3 can be throttled or cancelled, if a certain number of requests per second is exceeded.
    // Same goes to IAM, which is queried before every S3 request, if enabled. IAM has even lower RPS threshold.
@@ -849,24 +588,4 @@ mod tests {
        let err = RemotePath::new(Utf8Path::new("/")).expect_err("Should fail on absolute paths");
        assert_eq!(err.to_string(), "Path \"/\" is not relative");
    }
-
-    #[test]
-    fn parse_localfs_config_with_timeout() {
-        let input = "local_path = '.'
-timeout = '5s'";
-
-        let toml = input.parse::<toml_edit::Document>().unwrap();
-
-        let config = RemoteStorageConfig::from_toml(toml.as_item())
-            .unwrap()
-            .expect("it exists");
-
-        assert_eq!(
-            config,
-            RemoteStorageConfig {
-                storage: RemoteStorageKind::LocalFs(Utf8PathBuf::from(".")),
-                timeout: Duration::from_secs(5)
-            }
-        );
-    }
 }
--- a/libs/remote_storage/src/s3_bucket.rs
+++ b/libs/remote_storage/src/s3_bucket.rs
@@ -46,12 +46,12 @@ use utils::backoff;

 use super::StorageMetadata;
 use crate::{
+    config::S3Config,
    error::Cancelled,
    metrics::{start_counting_cancelled_wait, start_measuring_requests},
    support::PermitCarrying,
    ConcurrencyLimiter, Download, DownloadError, Listing, ListingMode, RemotePath, RemoteStorage,
-    S3Config, TimeTravelError, TimeoutOrCancel, MAX_KEYS_PER_DELETE,
-    REMOTE_STORAGE_PREFIX_SEPARATOR,
+    TimeTravelError, TimeoutOrCancel, MAX_KEYS_PER_DELETE, REMOTE_STORAGE_PREFIX_SEPARATOR,
 };

 use crate::metrics::AttemptOutcome;
--- a/libs/tenant_size_model/src/calculation.rs
+++ b/libs/tenant_size_model/src/calculation.rs
@@ -34,10 +34,10 @@ struct SegmentSize {
 }

 struct SizeAlternatives {
-    // cheapest alternative if parent is available.
+    /// cheapest alternative if parent is available.
    incremental: SegmentSize,

-    // cheapest alternative if parent node is not available
+    /// cheapest alternative if parent node is not available
    non_incremental: Option<SegmentSize>,
 }

--- a/libs/tenant_size_model/src/svg.rs
+++ b/libs/tenant_size_model/src/svg.rs
@@ -3,10 +3,17 @@ use std::fmt::Write;

 const SVG_WIDTH: f32 = 500.0;

+/// Different branch kind for SVG drawing.
+#[derive(PartialEq)]
+pub enum SvgBranchKind {
+    Timeline,
+    Lease,
+}
+
 struct SvgDraw<'a> {
    storage: &'a StorageModel,
    branches: &'a [String],
-    seg_to_branch: &'a [usize],
+    seg_to_branch: &'a [(usize, SvgBranchKind)],
    sizes: &'a [SegmentSizeResult],

    // layout
@@ -42,13 +49,18 @@ fn draw_legend(result: &mut String) -> anyhow::Result<()> {
        "<line x1=\"5\" y1=\"70\" x2=\"15\" y2=\"70\" stroke-width=\"1\" stroke=\"gray\" />"
    )?;
    writeln!(result, "<text x=\"20\" y=\"75\">WAL not retained</text>")?;
+    writeln!(
+        result,
+        "<line x1=\"10\" y1=\"85\" x2=\"10\" y2=\"95\" stroke-width=\"3\" stroke=\"blue\" />"
+    )?;
+    writeln!(result, "<text x=\"20\" y=\"95\">LSN lease</text>")?;
    Ok(())
 }

 pub fn draw_svg(
    storage: &StorageModel,
    branches: &[String],
-    seg_to_branch: &[usize],
+    seg_to_branch: &[(usize, SvgBranchKind)],
    sizes: &SizeResult,
 ) -> anyhow::Result<String> {
    let mut draw = SvgDraw {
@@ -100,7 +112,7 @@ impl<'a> SvgDraw<'a> {

        // Layout the timelines on Y dimension.
        // TODO
-        let mut y = 100.0;
+        let mut y = 120.0;
        let mut branch_y_coordinates = Vec::new();
        for _branch in self.branches {
            branch_y_coordinates.push(y);
@@ -109,7 +121,7 @@ impl<'a> SvgDraw<'a> {

        // Calculate coordinates for each point
        let seg_coordinates = std::iter::zip(segments, self.seg_to_branch)
-            .map(|(seg, branch_id)| {
+            .map(|(seg, (branch_id, _))| {
                let x = (seg.lsn - min_lsn) as f32 / xscale;
                let y = branch_y_coordinates[*branch_id];
                (x, y)
@@ -175,6 +187,22 @@ impl<'a> SvgDraw<'a> {

        // draw a snapshot point if it's needed
        let (coord_x, coord_y) = self.seg_coordinates[seg_id];
+
+        let (_, kind) = &self.seg_to_branch[seg_id];
+        if kind == &SvgBranchKind::Lease {
+            let (x1, y1) = (coord_x, coord_y - 10.0);
+            let (x2, y2) = (coord_x, coord_y + 10.0);
+
+            let style = "stroke-width=\"3\" stroke=\"blue\"";
+
+            writeln!(
+                result,
+                "<line x1=\"{x1}\" y1=\"{y1}\" x2=\"{x2}\" y2=\"{y2}\" {style}>",
+            )?;
+            writeln!(result, "  <title>leased lsn at {}</title>", seg.lsn)?;
+            writeln!(result, "</line>")?;
+        }
+
        if self.sizes[seg_id].method == SegmentMethod::SnapshotHere {
            writeln!(
                result,
--- a/libs/utils/Cargo.toml
+++ b/libs/utils/Cargo.toml
@@ -40,6 +40,7 @@ thiserror.workspace = true
 tokio.workspace = true
 tokio-tar.workspace = true
 tokio-util.workspace = true
+toml_edit.workspace = true
 tracing.workspace = true
 tracing-error.workspace = true
 tracing-subscriber = { workspace = true, features = ["json", "registry"] }
--- a/libs/utils/src/generation.rs
+++ b/libs/utils/src/generation.rs
@@ -9,20 +9,11 @@ use serde::{Deserialize, Serialize};
 /// numbers are used.
 #[derive(Copy, Clone, Eq, PartialEq, PartialOrd, Ord, Hash)]
 pub enum Generation {
-    // Generations with this magic value will not add a suffix to S3 keys, and will not
-    // be included in persisted index_part.json.  This value is only to be used
-    // during migration from pre-generation metadata to generation-aware metadata,
-    // and should eventually go away.
-    //
-    // A special Generation is used rather than always wrapping Generation in an Option,
-    // so that code handling generations doesn't have to be aware of the legacy
-    // case everywhere it touches a generation.
+    // The None Generation is used in the metadata of layers written before generations were
+    // introduced.  A running Tenant always has a valid generation, but the layer metadata may
+    // include None generations.
    None,
-    // Generations with this magic value may never be used to construct S3 keys:
-    // we will panic if someone tries to.  This is for Tenants in the "Broken" state,
-    // so that we can satisfy their constructor with a Generation without risking
-    // a code bug using it in an S3 write (broken tenants should never write)
-    Broken,
+
    Valid(u32),
 }

@@ -42,11 +33,6 @@ impl Generation {
        Self::None
    }

-    // Create a new generation that will panic if you try to use get_suffix
-    pub fn broken() -> Self {
-        Self::Broken
-    }
-
    pub const fn new(v: u32) -> Self {
        Self::Valid(v)
    }
@@ -60,9 +46,6 @@ impl Generation {
        match self {
            Self::Valid(v) => GenerationFileSuffix(Some(*v)),
            Self::None => GenerationFileSuffix(None),
-            Self::Broken => {
-                panic!("Tried to use a broken generation");
-            }
        }
    }

@@ -86,7 +69,6 @@ impl Generation {
                }
            }
            Self::None => Self::None,
-            Self::Broken => panic!("Attempted to use a broken generation"),
        }
    }

@@ -95,7 +77,6 @@ impl Generation {
        match self {
            Self::Valid(n) => Self::Valid(*n + 1),
            Self::None => Self::Valid(1),
-            Self::Broken => panic!("Attempted to use a broken generation"),
        }
    }

@@ -128,7 +109,7 @@ impl Serialize for Generation {
        if let Self::Valid(v) = self {
            v.serialize(serializer)
        } else {
-            // We should never be asked to serialize a None or Broken.  Structures
+            // We should never be asked to serialize a None. Structures
            // that include an optional generation should convert None to an
            // Option<Generation>::None
            Err(serde::ser::Error::custom(
@@ -159,9 +140,6 @@ impl Debug for Generation {
            Self::None => {
                write!(f, "<none>")
            }
-            Self::Broken => {
-                write!(f, "<broken>")
-            }
        }
    }
 }
--- a/libs/utils/src/http/json.rs
+++ b/libs/utils/src/http/json.rs
@@ -8,22 +8,15 @@ use super::error::ApiError;
 pub async fn json_request<T: for<'de> Deserialize<'de>>(
    request: &mut Request<Body>,
 ) -> Result<T, ApiError> {
-    json_request_or_empty_body(request)
-        .await?
-        .context("missing request body")
-        .map_err(ApiError::BadRequest)
-}
-
-/// Will be removed as part of <https://github.com/neondatabase/neon/issues/4282>
-pub async fn json_request_or_empty_body<T: for<'de> Deserialize<'de>>(
-    request: &mut Request<Body>,
-) -> Result<Option<T>, ApiError> {
    let body = hyper::body::aggregate(request.body_mut())
        .await
        .context("Failed to read request body")
        .map_err(ApiError::BadRequest)?;
+
    if body.remaining() == 0 {
-        return Ok(None);
+        return Err(ApiError::BadRequest(anyhow::anyhow!(
+            "missing request body"
+        )));
    }

    let mut deser = serde_json::de::Deserializer::from_reader(body.reader());
@@ -31,7 +24,6 @@ pub async fn json_request_or_empty_body<T: for<'de> Deserialize<'de>>(
    serde_path_to_error::deserialize(&mut deser)
        // intentionally stringify because the debug version is not helpful in python logs
        .map_err(|e| anyhow::anyhow!("Failed to parse json request: {e}"))
-        .map(Some)
        .map_err(ApiError::BadRequest)
 }

--- a/libs/utils/src/lib.rs
+++ b/libs/utils/src/lib.rs
@@ -94,6 +94,8 @@ pub mod env;

 pub mod poison;

+pub mod toml_edit_ext;
+
 /// This is a shortcut to embed git sha into binaries and avoid copying the same build script to all packages
 ///
 /// we have several cases:
--- a/libs/utils/src/toml_edit_ext.rs
+++ b/libs/utils/src/toml_edit_ext.rs
@@ -0,0 +1,22 @@
+#[derive(Debug, thiserror::Error)]
+pub enum Error {
+    #[error("item is not a document")]
+    ItemIsNotADocument,
+    #[error(transparent)]
+    Serde(toml_edit::de::Error),
+}
+
+pub fn deserialize_item<T>(item: &toml_edit::Item) -> Result<T, Error>
+where
+    T: serde::de::DeserializeOwned,
+{
+    let document: toml_edit::Document = match item {
+        toml_edit::Item::Table(toml) => toml.clone().into(),
+        toml_edit::Item::Value(toml_edit::Value::InlineTable(toml)) => {
+            toml.clone().into_table().into()
+        }
+        _ => return Err(Error::ItemIsNotADocument),
+    };
+
+    toml_edit::de::from_document(document).map_err(Error::Serde)
+}
--- a/libs/walproposer/src/walproposer.rs
+++ b/libs/walproposer/src/walproposer.rs
@@ -1,3 +1,5 @@
+#![allow(clippy::todo)]
+
 use std::ffi::CString;

 use crate::{
--- a/pageserver/benches/bench_walredo.rs
+++ b/pageserver/benches/bench_walredo.rs
@@ -48,6 +48,7 @@
 //! medium/128        time:   [8.8311 ms 8.9849 ms 9.1263 ms]
 //! ```

+use anyhow::Context;
 use bytes::{Buf, Bytes};
 use criterion::{BenchmarkId, Criterion};
 use pageserver::{config::PageServerConf, walrecord::NeonWalRecord, walredo::PostgresRedoManager};
@@ -188,6 +189,7 @@ impl Request {
        manager
            .request_redo(*key, *lsn, base_img.clone(), records.clone(), *pg_version)
            .await
+            .context("request_redo")
    }

    fn pg_record(will_init: bool, bytes: &'static [u8]) -> NeonWalRecord {
--- a/pageserver/client/src/mgmt_api.rs
+++ b/pageserver/client/src/mgmt_api.rs
@@ -205,15 +205,6 @@ impl Client {
        Ok(())
    }

-    pub async fn tenant_create(&self, req: &TenantCreateRequest) -> Result<TenantId> {
-        let uri = format!("{}/v1/tenant", self.mgmt_api_endpoint);
-        self.request(Method::POST, &uri, req)
-            .await?
-            .json()
-            .await
-            .map_err(Error::ReceiveBody)
-    }
-
    /// The tenant deletion API can return 202 if deletion is incomplete, or
    /// 404 if it is complete.  Callers are responsible for checking the status
    /// code and retrying.  Error codes other than 404 will return Err().
--- a/pageserver/ctl/src/draw_timeline_dir.rs
+++ b/pageserver/ctl/src/draw_timeline_dir.rs
@@ -83,10 +83,18 @@ fn parse_filename(name: &str) -> (Range<Key>, Range<Lsn>) {
    let keys: Vec<&str> = split[0].split('-').collect();
    let mut lsns: Vec<&str> = split[1].split('-').collect();

+    // The current format of the layer file name: 000000067F0000000400000B150100000000-000000067F0000000400000D350100000000__00000000014B7AC8-v1-00000001
+
+    // Handle generation number `-00000001` part
    if lsns.last().expect("should").len() == 8 {
        lsns.pop();
    }

+    // Handle version number `-v1` part
+    if lsns.last().expect("should").starts_with('v') {
+        lsns.pop();
+    }
+
    if lsns.len() == 1 {
        lsns.push(lsns[0]);
    }
--- a/pageserver/ctl/src/main.rs
+++ b/pageserver/ctl/src/main.rs
@@ -178,7 +178,7 @@ async fn main() -> anyhow::Result<()> {
            let toml_item = toml_document
                .get("remote_storage")
                .expect("need remote_storage");
-            let config = RemoteStorageConfig::from_toml(toml_item)?.expect("incomplete config");
+            let config = RemoteStorageConfig::from_toml(toml_item)?;
            let storage = remote_storage::GenericRemoteStorage::from_config(&config);
            let cancel = CancellationToken::new();
            storage
--- a/pageserver/src/basebackup.rs
+++ b/pageserver/src/basebackup.rs
@@ -348,35 +348,36 @@ where
                    self.add_rel(rel, rel).await?;
                }
            }
-
-            for (path, content) in self
-                .timeline
-                .list_aux_files(self.lsn, self.ctx)
-                .await
-                .map_err(|e| BasebackupError::Server(e.into()))?
-            {
-                if path.starts_with("pg_replslot") {
-                    let offs = pg_constants::REPL_SLOT_ON_DISK_OFFSETOF_RESTART_LSN;
-                    let restart_lsn = Lsn(u64::from_le_bytes(
-                        content[offs..offs + 8].try_into().unwrap(),
-                    ));
-                    info!("Replication slot {} restart LSN={}", path, restart_lsn);
-                    min_restart_lsn = Lsn::min(min_restart_lsn, restart_lsn);
-                } else if path == "pg_logical/replorigin_checkpoint" {
-                    // replorigin_checkoint is written only on compute shutdown, so it contains
-                    // deteriorated values. So we generate our own version of this file for the particular LSN
-                    // based on information about replorigins extracted from transaction commit records.
-                    // In future we will not generate AUX record for "pg_logical/replorigin_checkpoint" at all,
-                    // but now we should handle (skip) it for backward compatibility.
-                    continue;
-                }
-                let header = new_tar_header(&path, content.len() as u64)?;
-                self.ar
-                    .append(&header, &*content)
-                    .await
-                    .context("could not add aux file to basebackup tarball")?;
-            }
        }
+
+        for (path, content) in self
+            .timeline
+            .list_aux_files(self.lsn, self.ctx)
+            .await
+            .map_err(|e| BasebackupError::Server(e.into()))?
+        {
+            if path.starts_with("pg_replslot") {
+                let offs = pg_constants::REPL_SLOT_ON_DISK_OFFSETOF_RESTART_LSN;
+                let restart_lsn = Lsn(u64::from_le_bytes(
+                    content[offs..offs + 8].try_into().unwrap(),
+                ));
+                info!("Replication slot {} restart LSN={}", path, restart_lsn);
+                min_restart_lsn = Lsn::min(min_restart_lsn, restart_lsn);
+            } else if path == "pg_logical/replorigin_checkpoint" {
+                // replorigin_checkoint is written only on compute shutdown, so it contains
+                // deteriorated values. So we generate our own version of this file for the particular LSN
+                // based on information about replorigins extracted from transaction commit records.
+                // In future we will not generate AUX record for "pg_logical/replorigin_checkpoint" at all,
+                // but now we should handle (skip) it for backward compatibility.
+                continue;
+            }
+            let header = new_tar_header(&path, content.len() as u64)?;
+            self.ar
+                .append(&header, &*content)
+                .await
+                .context("could not add aux file to basebackup tarball")?;
+        }
+
        if min_restart_lsn != Lsn::MAX {
            info!(
                "Min restart LSN for logical replication is {}",
--- a/pageserver/src/bin/pageserver.rs
+++ b/pageserver/src/bin/pageserver.rs
@@ -421,6 +421,10 @@ fn start_pageserver(
        background_jobs_can_start: background_jobs_barrier.clone(),
    };

+    info!(config=?conf.l0_flush, "using l0_flush config");
+    let l0_flush_global_state =
+        pageserver::l0_flush::L0FlushGlobalState::new(conf.l0_flush.clone());
+
    // Scan the local 'tenants/' directory and start loading the tenants
    let deletion_queue_client = deletion_queue.new_client();
    let tenant_manager = BACKGROUND_RUNTIME.block_on(mgr::init_tenant_mgr(
@@ -429,6 +433,7 @@ fn start_pageserver(
            broker_client: broker_client.clone(),
            remote_storage: remote_storage.clone(),
            deletion_queue_client,
+            l0_flush_global_state,
        },
        order,
        shutdown_pageserver.clone(),
--- a/pageserver/src/config.rs
+++ b/pageserver/src/config.rs
@@ -5,7 +5,7 @@
 //! See also `settings.md` for better description on every parameter.

 use anyhow::{anyhow, bail, ensure, Context, Result};
-use pageserver_api::shard::TenantShardId;
+use pageserver_api::{models::ImageCompressionAlgorithm, shard::TenantShardId};
 use remote_storage::{RemotePath, RemoteStorageConfig};
 use serde;
 use serde::de::IntoDeserializer;
@@ -30,18 +30,13 @@ use utils::{
    logging::LogFormat,
 };

-use crate::tenant::timeline::GetVectoredImpl;
 use crate::tenant::vectored_blob_io::MaxVectoredReadBytes;
 use crate::tenant::{config::TenantConfOpt, timeline::GetImpl};
-use crate::tenant::{
-    TENANTS_SEGMENT_NAME, TENANT_DELETED_MARKER_FILE_NAME, TIMELINES_SEGMENT_NAME,
-};
+use crate::tenant::{TENANTS_SEGMENT_NAME, TIMELINES_SEGMENT_NAME};
 use crate::{disk_usage_eviction_task::DiskUsageEvictionTaskConfig, virtual_file::io_engine};
+use crate::{l0_flush::L0FlushConfig, tenant::timeline::GetVectoredImpl};
 use crate::{tenant::config::TenantConf, virtual_file};
-use crate::{
-    TENANT_CONFIG_NAME, TENANT_HEATMAP_BASENAME, TENANT_LOCATION_CONFIG_NAME,
-    TIMELINE_DELETE_MARK_SUFFIX,
-};
+use crate::{TENANT_HEATMAP_BASENAME, TENANT_LOCATION_CONFIG_NAME, TIMELINE_DELETE_MARK_SUFFIX};

 use self::defaults::DEFAULT_CONCURRENT_TENANT_WARMUP;

@@ -55,6 +50,7 @@ pub mod defaults {
        DEFAULT_HTTP_LISTEN_ADDR, DEFAULT_HTTP_LISTEN_PORT, DEFAULT_PG_LISTEN_ADDR,
        DEFAULT_PG_LISTEN_PORT,
    };
+    use pageserver_api::models::ImageCompressionAlgorithm;
    pub use storage_broker::DEFAULT_ENDPOINT as BROKER_DEFAULT_ENDPOINT;

    pub const DEFAULT_WAIT_LSN_TIMEOUT: &str = "60 s";
@@ -95,6 +91,9 @@ pub mod defaults {

    pub const DEFAULT_MAX_VECTORED_READ_BYTES: usize = 128 * 1024; // 128 KiB

+    pub const DEFAULT_IMAGE_COMPRESSION: ImageCompressionAlgorithm =
+        ImageCompressionAlgorithm::DisabledNoDecompress;
+
    pub const DEFAULT_VALIDATE_VECTORED_GET: bool = true;

    pub const DEFAULT_EPHEMERAL_BYTES_PER_MEMORY_KB: usize = 0;
@@ -164,7 +163,7 @@ pub mod defaults {

 #ephemeral_bytes_per_memory_kb = {DEFAULT_EPHEMERAL_BYTES_PER_MEMORY_KB}

-[remote_storage]
+#[remote_storage]

 "#
    );
@@ -290,12 +289,16 @@ pub struct PageServerConf {

    pub validate_vectored_get: bool,

+    pub image_compression: ImageCompressionAlgorithm,
+
    /// How many bytes of ephemeral layer content will we allow per kilobyte of RAM.  When this
    /// is exceeded, we start proactively closing ephemeral layers to limit the total amount
    /// of ephemeral data.
    ///
    /// Setting this to zero disables limits on total ephemeral layer size.
    pub ephemeral_bytes_per_memory_kb: usize,
+
+    pub l0_flush: L0FlushConfig,
 }

 /// We do not want to store this in a PageServerConf because the latter may be logged
@@ -400,7 +403,11 @@ struct PageServerConfigBuilder {

    validate_vectored_get: BuilderValue<bool>,

+    image_compression: BuilderValue<ImageCompressionAlgorithm>,
+
    ephemeral_bytes_per_memory_kb: BuilderValue<usize>,
+
+    l0_flush: BuilderValue<L0FlushConfig>,
 }

 impl PageServerConfigBuilder {
@@ -487,8 +494,10 @@ impl PageServerConfigBuilder {
            max_vectored_read_bytes: Set(MaxVectoredReadBytes(
                NonZeroUsize::new(DEFAULT_MAX_VECTORED_READ_BYTES).unwrap(),
            )),
+            image_compression: Set(DEFAULT_IMAGE_COMPRESSION),
            validate_vectored_get: Set(DEFAULT_VALIDATE_VECTORED_GET),
            ephemeral_bytes_per_memory_kb: Set(DEFAULT_EPHEMERAL_BYTES_PER_MEMORY_KB),
+            l0_flush: Set(L0FlushConfig::default()),
        }
    }
 }
@@ -672,10 +681,18 @@ impl PageServerConfigBuilder {
        self.validate_vectored_get = BuilderValue::Set(value);
    }

+    pub fn get_image_compression(&mut self, value: ImageCompressionAlgorithm) {
+        self.image_compression = BuilderValue::Set(value);
+    }
+
    pub fn get_ephemeral_bytes_per_memory_kb(&mut self, value: usize) {
        self.ephemeral_bytes_per_memory_kb = BuilderValue::Set(value);
    }

+    pub fn l0_flush(&mut self, value: L0FlushConfig) {
+        self.l0_flush = BuilderValue::Set(value);
+    }
+
    pub fn build(self) -> anyhow::Result<PageServerConf> {
        let default = Self::default_values();

@@ -732,7 +749,9 @@ impl PageServerConfigBuilder {
                get_impl,
                max_vectored_read_bytes,
                validate_vectored_get,
+                image_compression,
                ephemeral_bytes_per_memory_kb,
+                l0_flush,
            }
            CUSTOM LOGIC
            {
@@ -812,15 +831,11 @@ impl PageServerConf {
    }

    /// Points to a place in pageserver's local directory,
-    /// where certain tenant's tenantconf file should be located.
-    ///
-    /// Legacy: superseded by tenant_location_config_path.  Eventually
-    /// remove this function.
-    pub fn tenant_config_path(&self, tenant_shard_id: &TenantShardId) -> Utf8PathBuf {
-        self.tenant_path(tenant_shard_id).join(TENANT_CONFIG_NAME)
-    }
-
-    pub fn tenant_location_config_path(&self, tenant_shard_id: &TenantShardId) -> Utf8PathBuf {
+    /// where certain tenant's LocationConf be stored.
+    pub(crate) fn tenant_location_config_path(
+        &self,
+        tenant_shard_id: &TenantShardId,
+    ) -> Utf8PathBuf {
        self.tenant_path(tenant_shard_id)
            .join(TENANT_LOCATION_CONFIG_NAME)
    }
@@ -855,14 +870,6 @@ impl PageServerConf {
        )
    }

-    pub(crate) fn tenant_deleted_mark_file_path(
-        &self,
-        tenant_shard_id: &TenantShardId,
-    ) -> Utf8PathBuf {
-        self.tenant_path(tenant_shard_id)
-            .join(TENANT_DELETED_MARKER_FILE_NAME)
-    }
-
    pub fn traces_path(&self) -> Utf8PathBuf {
        self.workdir.join("traces")
    }
@@ -935,7 +942,7 @@ impl PageServerConf {
                "http_auth_type" => builder.http_auth_type(parse_toml_from_str(key, item)?),
                "pg_auth_type" => builder.pg_auth_type(parse_toml_from_str(key, item)?),
                "remote_storage" => {
-                    builder.remote_storage_config(RemoteStorageConfig::from_toml(item)?)
+                    builder.remote_storage_config(Some(RemoteStorageConfig::from_toml(item).context("remote_storage")?))
                }
                "tenant_config" => {
                    t_conf = TenantConfOpt::try_from(item.to_owned()).context(format!("failed to parse: '{key}'"))?;
@@ -963,7 +970,7 @@ impl PageServerConf {
                    builder.metric_collection_endpoint(Some(endpoint));
                },
                "metric_collection_bucket" => {
-                    builder.metric_collection_bucket(RemoteStorageConfig::from_toml(item)?)
+                    builder.metric_collection_bucket(Some(RemoteStorageConfig::from_toml(item)?))
                }
                "synthetic_size_calculation_interval" =>
                    builder.synthetic_size_calculation_interval(parse_toml_duration(key, item)?),
@@ -1021,9 +1028,15 @@ impl PageServerConf {
                "validate_vectored_get" => {
                    builder.get_validate_vectored_get(parse_toml_bool("validate_vectored_get", item)?)
                }
+                "image_compression" => {
+                    builder.get_image_compression(parse_toml_from_str("image_compression", item)?)
+                }
                "ephemeral_bytes_per_memory_kb" => {
                    builder.get_ephemeral_bytes_per_memory_kb(parse_toml_u64("ephemeral_bytes_per_memory_kb", item)? as usize)
                }
+                "l0_flush" => {
+                    builder.l0_flush(utils::toml_edit_ext::deserialize_item(item).context("l0_flush")?)
+                }
                _ => bail!("unrecognized pageserver option '{key}'"),
            }
        }
@@ -1105,8 +1118,10 @@ impl PageServerConf {
                NonZeroUsize::new(defaults::DEFAULT_MAX_VECTORED_READ_BYTES)
                    .expect("Invalid default constant"),
            ),
+            image_compression: defaults::DEFAULT_IMAGE_COMPRESSION,
            validate_vectored_get: defaults::DEFAULT_VALIDATE_VECTORED_GET,
            ephemeral_bytes_per_memory_kb: defaults::DEFAULT_EPHEMERAL_BYTES_PER_MEMORY_KB,
+            l0_flush: L0FlushConfig::default(),
        }
    }
 }
@@ -1345,7 +1360,9 @@ background_task_maximum_delay = '334 s'
                        .expect("Invalid default constant")
                ),
                validate_vectored_get: defaults::DEFAULT_VALIDATE_VECTORED_GET,
+                image_compression: defaults::DEFAULT_IMAGE_COMPRESSION,
                ephemeral_bytes_per_memory_kb: defaults::DEFAULT_EPHEMERAL_BYTES_PER_MEMORY_KB,
+                l0_flush: L0FlushConfig::default(),
            },
            "Correct defaults should be used when no config values are provided"
        );
@@ -1418,7 +1435,9 @@ background_task_maximum_delay = '334 s'
                        .expect("Invalid default constant")
                ),
                validate_vectored_get: defaults::DEFAULT_VALIDATE_VECTORED_GET,
+                image_compression: defaults::DEFAULT_IMAGE_COMPRESSION,
                ephemeral_bytes_per_memory_kb: defaults::DEFAULT_EPHEMERAL_BYTES_PER_MEMORY_KB,
+                l0_flush: L0FlushConfig::default(),
            },
            "Should be able to parse all basic config values correctly"
        );
@@ -1463,7 +1482,7 @@ broker_endpoint = '{broker_endpoint}'
            assert_eq!(
                parsed_remote_storage_config,
                RemoteStorageConfig {
-                    storage: RemoteStorageKind::LocalFs(local_storage_path.clone()),
+                    storage: RemoteStorageKind::LocalFs { local_path: local_storage_path.clone() },
                    timeout: RemoteStorageConfig::DEFAULT_TIMEOUT,
                },
                "Remote storage config should correctly parse the local FS config and fill other storage defaults"
@@ -1698,6 +1717,19 @@ threshold = "20m"
        }
    }

+    #[test]
+    fn empty_remote_storage_is_error() {
+        let tempdir = tempdir().unwrap();
+        let (workdir, _) = prepare_fs(&tempdir).unwrap();
+        let input = r#"
+remote_storage = {}
+        "#;
+        let doc = toml_edit::Document::from_str(input).unwrap();
+        let err = PageServerConf::parse_and_validate(&doc, &workdir)
+            .expect_err("empty remote_storage field should fail, don't specify it if you want no remote_storage");
+        assert!(format!("{err}").contains("remote_storage"), "{err}");
+    }
+
    fn prepare_fs(tempdir: &Utf8TempDir) -> anyhow::Result<(Utf8PathBuf, Utf8PathBuf)> {
        let tempdir_path = tempdir.path();

--- a/pageserver/src/deletion_queue.rs
+++ b/pageserver/src/deletion_queue.rs
@@ -382,17 +382,6 @@ pub enum DeletionQueueError {
 }

 impl DeletionQueueClient {
-    pub(crate) fn broken() -> Self {
-        // Channels whose receivers are immediately dropped.
-        let (tx, _rx) = tokio::sync::mpsc::unbounded_channel();
-        let (executor_tx, _executor_rx) = tokio::sync::mpsc::channel(1);
-        Self {
-            tx,
-            executor_tx,
-            lsn_table: Arc::default(),
-        }
-    }
-
    /// This is cancel-safe.  If you drop the future before it completes, the message
    /// is not pushed, although in the context of the deletion queue it doesn't matter: once
    /// we decide to do a deletion the decision is always final.
@@ -850,7 +839,9 @@ mod test {
        std::fs::create_dir_all(remote_fs_dir)?;
        let remote_fs_dir = harness.conf.workdir.join("remote_fs").canonicalize_utf8()?;
        let storage_config = RemoteStorageConfig {
-            storage: RemoteStorageKind::LocalFs(remote_fs_dir.clone()),
+            storage: RemoteStorageKind::LocalFs {
+                local_path: remote_fs_dir.clone(),
+            },
            timeout: RemoteStorageConfig::DEFAULT_TIMEOUT,
        };
        let storage = GenericRemoteStorage::from_config(&storage_config).unwrap();
--- a/pageserver/src/deletion_queue/validator.rs
+++ b/pageserver/src/deletion_queue/validator.rs
@@ -190,7 +190,7 @@ where
                }
            } else {
                // If we failed validation, then do not apply any of the projected updates
-                warn!("Dropped remote consistent LSN updates for tenant {tenant_id} in stale generation {:?}", tenant_lsn_state.generation);
+                info!("Dropped remote consistent LSN updates for tenant {tenant_id} in stale generation {:?}", tenant_lsn_state.generation);
                metrics::DELETION_QUEUE.dropped_lsn_updates.inc();
            }
        }
@@ -225,7 +225,7 @@ where
                    && (tenant.generation == *validated_generation);

                if !this_list_valid {
-                    warn!("Dropping stale deletions for tenant {tenant_id} in generation {:?}, objects may be leaked", tenant.generation);
+                    info!("Dropping stale deletions for tenant {tenant_id} in generation {:?}, objects may be leaked", tenant.generation);
                    metrics::DELETION_QUEUE.keys_dropped.inc_by(tenant.len() as u64);
                    mutated = true;
                } else {
--- a/pageserver/src/http/openapi_spec.yml
+++ b/pageserver/src/http/openapi_spec.yml
@@ -236,6 +236,13 @@ paths:
            type: string
            format: date-time
          description: A timestamp to get the LSN
+        - name: with_lease
+          in: query
+          required: false
+          schema:
+            type: boolean
+          description: Whether to grant a lease to the corresponding LSN. Default to false.
+
      responses:
        "200":
          description: OK
@@ -258,15 +265,19 @@ paths:
          type: string
          format: hex
    post:
-      description: Obtain lease for the given LSN
-      parameters:
-        - name: lsn
-          in: query
-          required: true
-          schema:
-            type: string
-            format: hex
-          description: A LSN to obtain the lease for
+      description: Obtains a lease for the given LSN.
+      requestBody:
+        content:
+          application/json:
+            schema:
+              type: object
+              required:
+               - lsn
+              properties:
+                lsn:
+                  description: A LSN to obtain the lease for.
+                  type: string
+                  format: hex
      responses:
        "200":
          description: OK
@@ -360,16 +371,7 @@ paths:
                $ref: "#/components/schemas/TenantLocationConfigResponse"
        "409":
          description: |
-            The tenant is already known to Pageserver in some way,
-            and hence this `/attach` call has been rejected.
-
-            Some examples of how this can happen:
-            - tenant was created on this pageserver
-            - tenant attachment was started by an earlier call to `/attach`.
-
-            Callers should poll the tenant status's `attachment_status` field,
-            like for status 202. See the longer description for `POST /attach`
-            for details.
+            The tenant is already being modified, perhaps by a concurrent call to this API
          content:
            application/json:
              schema:
@@ -755,8 +757,6 @@ components:
              For example this can be caused by s3 being unreachable. The retry may be implemented
              with call to detach, though it would be better to not automate it and inspec failed state
              manually before proceeding with a retry.
-
-            See the tenant `/attach` endpoint for more information.
          type: object
          required:
            - slug
@@ -1029,6 +1029,10 @@ components:
        kind:
          type: string
          enum: [past, present, future, nodata]
+        valid_until:
+          type: string
+          format: date-time
+          description: The expiration time of the granted lease.

    LsnLease:
      type: object
--- a/pageserver/src/http/routes.rs
+++ b/pageserver/src/http/routes.rs
@@ -21,6 +21,8 @@ use pageserver_api::models::IngestAuxFilesRequest;
 use pageserver_api::models::ListAuxFilesRequest;
 use pageserver_api::models::LocationConfig;
 use pageserver_api::models::LocationConfigListResponse;
+use pageserver_api::models::LsnLease;
+use pageserver_api::models::LsnLeaseRequest;
 use pageserver_api::models::ShardParameters;
 use pageserver_api::models::TenantDetails;
 use pageserver_api::models::TenantLocationConfigResponse;
@@ -30,32 +32,28 @@ 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,
-    TenantLocationConfigRequest,
+    DownloadRemoteLayersTaskSpawnRequest, LocationConfigMode, TenantLocationConfigRequest,
 };
 use pageserver_api::shard::ShardCount;
 use pageserver_api::shard::TenantShardId;
 use remote_storage::DownloadError;
 use remote_storage::GenericRemoteStorage;
 use remote_storage::TimeTravelError;
-use tenant_size_model::{SizeResult, StorageModel};
+use tenant_size_model::{svg::SvgBranchKind, SizeResult, StorageModel};
 use tokio_util::sync::CancellationToken;
 use tracing::*;
 use utils::auth::JwtAuth;
 use utils::failpoint_support::failpoints_handler;
 use utils::http::endpoint::prometheus_metrics_handler;
 use utils::http::endpoint::request_span;
-use utils::http::json::json_request_or_empty_body;
 use utils::http::request::{get_request_param, must_get_query_param, parse_query_param};

 use crate::context::{DownloadBehavior, RequestContext};
 use crate::deletion_queue::DeletionQueueClient;
-use crate::metrics::{StorageTimeOperation, STORAGE_TIME_GLOBAL};
 use crate::pgdatadir_mapping::LsnForTimestamp;
 use crate::task_mgr::TaskKind;
 use crate::tenant::config::{LocationConf, TenantConfOpt};
@@ -77,13 +75,12 @@ use crate::tenant::timeline::CompactFlags;
 use crate::tenant::timeline::CompactionError;
 use crate::tenant::timeline::Timeline;
 use crate::tenant::GetTimelineError;
-use crate::tenant::SpawnMode;
 use crate::tenant::{LogicalSizeCalculationCause, PageReconstructError};
 use crate::{config::PageServerConf, tenant::mgr};
 use crate::{disk_usage_eviction_task, tenant};
 use pageserver_api::models::{
-    StatusResponse, TenantConfigRequest, TenantCreateRequest, TenantCreateResponse, TenantInfo,
-    TimelineCreateRequest, TimelineGcRequest, TimelineInfo,
+    StatusResponse, TenantConfigRequest, TenantInfo, TimelineCreateRequest, TimelineGcRequest,
+    TimelineInfo,
 };
 use utils::{
    auth::SwappableJwtAuth,
@@ -231,7 +228,7 @@ impl From<UpsertLocationError> for ApiError {
            BadRequest(e) => ApiError::BadRequest(e),
            Unavailable(_) => ApiError::ShuttingDown,
            e @ InProgress => ApiError::Conflict(format!("{e}")),
-            Flush(e) | Other(e) => ApiError::InternalServerError(e),
+            Flush(e) | InternalError(e) => ApiError::InternalServerError(e),
        }
    }
 }
@@ -329,14 +326,11 @@ impl From<crate::tenant::mgr::DeleteTimelineError> for ApiError {
    }
 }

-impl From<crate::tenant::delete::DeleteTenantError> for ApiError {
-    fn from(value: crate::tenant::delete::DeleteTenantError) -> Self {
-        use crate::tenant::delete::DeleteTenantError::*;
+impl From<crate::tenant::mgr::DeleteTenantError> for ApiError {
+    fn from(value: crate::tenant::mgr::DeleteTenantError) -> Self {
+        use crate::tenant::mgr::DeleteTenantError::*;
        match value {
-            Get(g) => ApiError::from(g),
-            Timeline(t) => ApiError::from(t),
            SlotError(e) => e.into(),
-            SlotUpsertError(e) => e.into(),
            Other(o) => ApiError::InternalServerError(o),
            Cancelled => ApiError::ShuttingDown,
        }
@@ -413,6 +407,8 @@ async fn build_timeline_info_common(

    let walreceiver_status = timeline.walreceiver_status();

+    let (pitr_history_size, within_ancestor_pitr) = timeline.get_pitr_history_stats();
+
    let info = TimelineInfo {
        tenant_id: timeline.tenant_shard_id,
        timeline_id: timeline.timeline_id,
@@ -433,6 +429,8 @@ async fn build_timeline_info_common(
        directory_entries_counts: timeline.get_directory_metrics().to_vec(),
        current_physical_size,
        current_logical_size_non_incremental: None,
+        pitr_history_size,
+        within_ancestor_pitr,
        timeline_dir_layer_file_size_sum: None,
        wal_source_connstr,
        last_received_msg_lsn,
@@ -731,6 +729,8 @@ async fn get_lsn_by_timestamp_handler(
        .map_err(ApiError::BadRequest)?;
    let timestamp_pg = postgres_ffi::to_pg_timestamp(timestamp);

+    let with_lease = parse_query_param(&request, "with_lease")?.unwrap_or(false);
+
    let ctx = RequestContext::new(TaskKind::MgmtRequest, DownloadBehavior::Download);

    let timeline =
@@ -739,10 +739,15 @@ async fn get_lsn_by_timestamp_handler(
    let result = timeline
        .find_lsn_for_timestamp(timestamp_pg, &cancel, &ctx)
        .await?;
+
    #[derive(serde::Serialize, Debug)]
    struct Result {
        lsn: Lsn,
        kind: &'static str,
+        #[serde(default)]
+        #[serde(skip_serializing_if = "Option::is_none")]
+        #[serde(flatten)]
+        lease: Option<LsnLease>,
    }
    let (lsn, kind) = match result {
        LsnForTimestamp::Present(lsn) => (lsn, "present"),
@@ -750,11 +755,28 @@ async fn get_lsn_by_timestamp_handler(
        LsnForTimestamp::Past(lsn) => (lsn, "past"),
        LsnForTimestamp::NoData(lsn) => (lsn, "nodata"),
    };
-    let result = Result { lsn, kind };
+
+    let lease = if with_lease {
+        timeline
+            .make_lsn_lease(lsn, timeline.get_lsn_lease_length_for_ts(), &ctx)
+            .inspect_err(|_| {
+                warn!("fail to grant a lease to {}", lsn);
+            })
+            .ok()
+    } else {
+        None
+    };
+
+    let result = Result { lsn, kind, lease };
+    let valid_until = result
+        .lease
+        .as_ref()
+        .map(|l| humantime::format_rfc3339_millis(l.valid_until).to_string());
    tracing::info!(
        lsn=?result.lsn,
        kind=%result.kind,
        timestamp=%timestamp_raw,
+        valid_until=?valid_until,
        "lsn_by_timestamp finished"
    );
    json_response(StatusCode::OK, result)
@@ -799,58 +821,6 @@ async fn get_timestamp_of_lsn_handler(
    }
 }

-async fn tenant_attach_handler(
-    mut request: Request<Body>,
-    _cancel: CancellationToken,
-) -> Result<Response<Body>, ApiError> {
-    let tenant_id: TenantId = parse_request_param(&request, "tenant_id")?;
-    check_permission(&request, Some(tenant_id))?;
-
-    let maybe_body: Option<TenantAttachRequest> = json_request_or_empty_body(&mut request).await?;
-    let tenant_conf = match &maybe_body {
-        Some(request) => TenantConfOpt::try_from(&*request.config).map_err(ApiError::BadRequest)?,
-        None => TenantConfOpt::default(),
-    };
-
-    let ctx = RequestContext::new(TaskKind::MgmtRequest, DownloadBehavior::Warn);
-
-    info!("Handling tenant attach {tenant_id}");
-
-    let state = get_state(&request);
-
-    let generation = get_request_generation(state, maybe_body.as_ref().and_then(|r| r.generation))?;
-
-    let tenant_shard_id = TenantShardId::unsharded(tenant_id);
-    let shard_params = ShardParameters::default();
-    let location_conf = LocationConf::attached_single(tenant_conf, generation, &shard_params);
-
-    let tenant = state
-        .tenant_manager
-        .upsert_location(tenant_shard_id, location_conf, None, SpawnMode::Eager, &ctx)
-        .await?;
-
-    let Some(tenant) = tenant else {
-        // This should never happen: indicates a bug in upsert_location
-        return Err(ApiError::InternalServerError(anyhow::anyhow!(
-            "Upsert succeeded but didn't return tenant!"
-        )));
-    };
-
-    // We might have successfully constructed a Tenant, but it could still
-    // end up in a broken state:
-    if let TenantState::Broken {
-        reason,
-        backtrace: _,
-    } = tenant.current_state()
-    {
-        return Err(ApiError::InternalServerError(anyhow::anyhow!(
-            "Tenant state is Broken: {reason}"
-        )));
-    }
-
-    json_response(StatusCode::ACCEPTED, ())
-}
-
 async fn timeline_delete_handler(
    request: Request<Body>,
    _cancel: CancellationToken,
@@ -881,26 +851,6 @@ async fn timeline_delete_handler(
    json_response(StatusCode::ACCEPTED, ())
 }

-async fn tenant_detach_handler(
-    request: Request<Body>,
-    _cancel: CancellationToken,
-) -> Result<Response<Body>, ApiError> {
-    let tenant_id: TenantId = parse_request_param(&request, "tenant_id")?;
-    check_permission(&request, Some(tenant_id))?;
-    // This is a legacy API (`/location_conf` is the replacement).  It only supports unsharded tenants
-    let tenant_shard_id = TenantShardId::unsharded(tenant_id);
-
-    let state = get_state(&request);
-    let conf = state.conf;
-    state
-        .tenant_manager
-        .detach_tenant(conf, tenant_shard_id, &state.deletion_queue_client)
-        .instrument(info_span!("tenant_detach", %tenant_id, shard_id=%tenant_shard_id.shard_slug()))
-        .await?;
-
-    json_response(StatusCode::OK, ())
-}
-
 async fn tenant_reset_handler(
    request: Request<Body>,
    _cancel: CancellationToken,
@@ -940,7 +890,9 @@ async fn tenant_list_handler(
            state: state.clone(),
            current_physical_size: None,
            attachment_status: state.attachment_status(),
-            generation: (*gen).into(),
+            generation: (*gen)
+                .into()
+                .expect("Tenants are always attached with a generation"),
        })
        .collect::<Vec<TenantInfo>>();

@@ -988,7 +940,10 @@ async fn tenant_status(
                state: state.clone(),
                current_physical_size: Some(current_physical_size),
                attachment_status: state.attachment_status(),
-                generation: tenant.generation().into(),
+                generation: tenant
+                    .generation()
+                    .into()
+                    .expect("Tenants are always attached with a generation"),
            },
            walredo: tenant.wal_redo_manager_status(),
            timelines: tenant.list_timeline_ids(),
@@ -1241,10 +1196,15 @@ fn synthetic_size_html_response(
        timeline_map.insert(ti.timeline_id, index);
        timeline_ids.push(ti.timeline_id.to_string());
    }
-    let seg_to_branch: Vec<usize> = inputs
+    let seg_to_branch: Vec<(usize, SvgBranchKind)> = inputs
        .segments
        .iter()
-        .map(|seg| *timeline_map.get(&seg.timeline_id).unwrap())
+        .map(|seg| {
+            (
+                *timeline_map.get(&seg.timeline_id).unwrap(),
+                seg.kind.into(),
+            )
+        })
        .collect();

    let svg =
@@ -1285,75 +1245,6 @@ pub fn html_response(status: StatusCode, data: String) -> Result<Response<Body>,
    Ok(response)
 }

-/// Helper for requests that may take a generation, which is mandatory
-/// when control_plane_api is set, but otherwise defaults to Generation::none()
-fn get_request_generation(state: &State, req_gen: Option<u32>) -> Result<Generation, ApiError> {
-    if state.conf.control_plane_api.is_some() {
-        req_gen
-            .map(Generation::new)
-            .ok_or(ApiError::BadRequest(anyhow!(
-                "generation attribute missing"
-            )))
-    } else {
-        // Legacy mode: all tenants operate with no generation
-        Ok(Generation::none())
-    }
-}
-
-async fn tenant_create_handler(
-    mut request: Request<Body>,
-    _cancel: CancellationToken,
-) -> Result<Response<Body>, ApiError> {
-    let request_data: TenantCreateRequest = json_request(&mut request).await?;
-    let target_tenant_id = request_data.new_tenant_id;
-    check_permission(&request, None)?;
-
-    let _timer = STORAGE_TIME_GLOBAL
-        .get_metric_with_label_values(&[StorageTimeOperation::CreateTenant.into()])
-        .expect("bug")
-        .start_timer();
-
-    let tenant_conf =
-        TenantConfOpt::try_from(&request_data.config).map_err(ApiError::BadRequest)?;
-
-    let state = get_state(&request);
-
-    let generation = get_request_generation(state, request_data.generation)?;
-
-    let ctx = RequestContext::new(TaskKind::MgmtRequest, DownloadBehavior::Warn);
-
-    let location_conf =
-        LocationConf::attached_single(tenant_conf, generation, &request_data.shard_parameters);
-
-    let new_tenant = state
-        .tenant_manager
-        .upsert_location(
-            target_tenant_id,
-            location_conf,
-            None,
-            SpawnMode::Create,
-            &ctx,
-        )
-        .await?;
-
-    let Some(new_tenant) = new_tenant else {
-        // This should never happen: indicates a bug in upsert_location
-        return Err(ApiError::InternalServerError(anyhow::anyhow!(
-            "Upsert succeeded but didn't return tenant!"
-        )));
-    };
-    // We created the tenant. Existing API semantics are that the tenant
-    // is Active when this function returns.
-    new_tenant
-        .wait_to_become_active(ACTIVE_TENANT_TIMEOUT)
-        .await?;
-
-    json_response(
-        StatusCode::CREATED,
-        TenantCreateResponse(new_tenant.tenant_shard_id().tenant_id),
-    )
-}
-
 async fn get_tenant_config_handler(
    request: Request<Body>,
    _cancel: CancellationToken,
@@ -1415,7 +1306,7 @@ async fn update_tenant_config_handler(

    crate::tenant::Tenant::persist_tenant_config(state.conf, &tenant_shard_id, &location_conf)
        .await
-        .map_err(ApiError::InternalServerError)?;
+        .map_err(|e| ApiError::InternalServerError(anyhow::anyhow!(e)))?;
    tenant.set_new_tenant_config(new_tenant_conf);

    json_response(StatusCode::OK, ())
@@ -1646,15 +1537,13 @@ async fn handle_tenant_break(

 // Obtains an lsn lease on the given timeline.
 async fn lsn_lease_handler(
-    request: Request<Body>,
+    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")?;
    check_permission(&request, Some(tenant_shard_id.tenant_id))?;
-
-    let lsn: Lsn = parse_query_param(&request, "lsn")?
-        .ok_or_else(|| ApiError::BadRequest(anyhow!("missing 'lsn' query parameter")))?;
+    let lsn = json_request::<LsnLeaseRequest>(&mut request).await?.lsn;

    let ctx = RequestContext::new(TaskKind::MgmtRequest, DownloadBehavior::Download);

@@ -1705,6 +1594,14 @@ async fn timeline_compact_handler(
    if Some(true) == parse_query_param::<_, bool>(&request, "force_image_layer_creation")? {
        flags |= CompactFlags::ForceImageLayerCreation;
    }
+    if Some(true) == parse_query_param::<_, bool>(&request, "enhanced_gc_bottom_most_compaction")? {
+        if !cfg!(feature = "testing") {
+            return Err(ApiError::InternalServerError(anyhow!(
+                "enhanced_gc_bottom_most_compaction is only available in testing mode"
+            )));
+        }
+        flags |= CompactFlags::EnhancedGcBottomMostCompaction;
+    }
    let wait_until_uploaded =
        parse_query_param::<_, bool>(&request, "wait_until_uploaded")?.unwrap_or(false);

@@ -2651,7 +2548,6 @@ pub fn make_router(
            api_handler(r, reload_auth_validation_keys_handler)
        })
        .get("/v1/tenant", |r| api_handler(r, tenant_list_handler))
-        .post("/v1/tenant", |r| api_handler(r, tenant_create_handler))
        .get("/v1/tenant/:tenant_shard_id", |r| {
            api_handler(r, tenant_status)
        })
@@ -2689,12 +2585,6 @@ pub fn make_router(
        .post("/v1/tenant/:tenant_shard_id/timeline", |r| {
            api_handler(r, timeline_create_handler)
        })
-        .post("/v1/tenant/:tenant_id/attach", |r| {
-            api_handler(r, tenant_attach_handler)
-        })
-        .post("/v1/tenant/:tenant_id/detach", |r| {
-            api_handler(r, tenant_detach_handler)
-        })
        .post("/v1/tenant/:tenant_shard_id/reset", |r| {
            api_handler(r, tenant_reset_handler)
        })
--- a/pageserver/src/l0_flush.rs
+++ b/pageserver/src/l0_flush.rs
@@ -0,0 +1,46 @@
+use std::{num::NonZeroUsize, sync::Arc};
+
+use crate::tenant::ephemeral_file;
+
+#[derive(Default, Debug, PartialEq, Eq, Clone, serde::Deserialize)]
+#[serde(tag = "mode", rename_all = "kebab-case", deny_unknown_fields)]
+pub enum L0FlushConfig {
+    #[default]
+    PageCached,
+    #[serde(rename_all = "snake_case")]
+    Direct { max_concurrency: NonZeroUsize },
+}
+
+#[derive(Clone)]
+pub struct L0FlushGlobalState(Arc<Inner>);
+
+pub(crate) enum Inner {
+    PageCached,
+    Direct { semaphore: tokio::sync::Semaphore },
+}
+
+impl L0FlushGlobalState {
+    pub fn new(config: L0FlushConfig) -> Self {
+        match config {
+            L0FlushConfig::PageCached => Self(Arc::new(Inner::PageCached)),
+            L0FlushConfig::Direct { max_concurrency } => {
+                let semaphore = tokio::sync::Semaphore::new(max_concurrency.get());
+                Self(Arc::new(Inner::Direct { semaphore }))
+            }
+        }
+    }
+
+    pub(crate) fn inner(&self) -> &Arc<Inner> {
+        &self.0
+    }
+}
+
+impl L0FlushConfig {
+    pub(crate) fn prewarm_on_write(&self) -> ephemeral_file::PrewarmPageCacheOnWrite {
+        use L0FlushConfig::*;
+        match self {
+            PageCached => ephemeral_file::PrewarmPageCacheOnWrite::Yes,
+            Direct { .. } => ephemeral_file::PrewarmPageCacheOnWrite::No,
+        }
+    }
+}
--- a/pageserver/src/lib.rs
+++ b/pageserver/src/lib.rs
@@ -11,6 +11,7 @@ pub mod deletion_queue;
 pub mod disk_usage_eviction_task;
 pub mod http;
 pub mod import_datadir;
+pub mod l0_flush;
 pub use pageserver_api::keyspace;
 pub mod aux_file;
 pub mod metrics;
@@ -113,11 +114,7 @@ pub async fn shutdown_pageserver(
 }

 /// Per-tenant configuration file.
-/// Full path: `tenants/<tenant_id>/config`.
-pub(crate) const TENANT_CONFIG_NAME: &str = "config";
-
-/// Per-tenant configuration file.
-/// Full path: `tenants/<tenant_id>/config`.
+/// Full path: `tenants/<tenant_id>/config-v1`.
 pub(crate) const TENANT_LOCATION_CONFIG_NAME: &str = "config-v1";

 /// Per-tenant copy of their remote heatmap, downloaded into the local
--- a/pageserver/src/metrics.rs
+++ b/pageserver/src/metrics.rs
@@ -8,7 +8,7 @@ use metrics::{
 };
 use once_cell::sync::Lazy;
 use pageserver_api::shard::TenantShardId;
-use strum::{EnumCount, IntoEnumIterator, VariantNames};
+use strum::{EnumCount, VariantNames};
 use strum_macros::{EnumVariantNames, IntoStaticStr};
 use tracing::warn;
 use utils::id::TimelineId;
@@ -53,9 +53,6 @@ pub(crate) enum StorageTimeOperation {

    #[strum(serialize = "find gc cutoffs")]
    FindGcCutoffs,
-
-    #[strum(serialize = "create tenant")]
-    CreateTenant,
 }

 pub(crate) static STORAGE_TIME_SUM_PER_TIMELINE: Lazy<CounterVec> = Lazy::new(|| {
@@ -467,6 +464,24 @@ static LAST_RECORD_LSN: Lazy<IntGaugeVec> = Lazy::new(|| {
    .expect("failed to define a metric")
 });

+static PITR_HISTORY_SIZE: Lazy<UIntGaugeVec> = Lazy::new(|| {
+    register_uint_gauge_vec!(
+        "pageserver_pitr_history_size",
+        "Data written since PITR cutoff on this timeline",
+        &["tenant_id", "shard_id", "timeline_id"]
+    )
+    .expect("failed to define a metric")
+});
+
+static TIMELINE_ARCHIVE_SIZE: Lazy<UIntGaugeVec> = Lazy::new(|| {
+    register_uint_gauge_vec!(
+        "pageserver_archive_size",
+        "Timeline's logical size if it is considered eligible for archival (outside PITR window), else zero",
+        &["tenant_id", "shard_id", "timeline_id"]
+    )
+    .expect("failed to define a metric")
+});
+
 static STANDBY_HORIZON: Lazy<IntGaugeVec> = Lazy::new(|| {
    register_int_gauge_vec!(
        "pageserver_standby_horizon",
@@ -479,7 +494,7 @@ static STANDBY_HORIZON: Lazy<IntGaugeVec> = Lazy::new(|| {
 static RESIDENT_PHYSICAL_SIZE: Lazy<UIntGaugeVec> = Lazy::new(|| {
    register_uint_gauge_vec!(
        "pageserver_resident_physical_size",
-        "The size of the layer files present in the pageserver's filesystem.",
+        "The size of the layer files present in the pageserver's filesystem, for attached locations.",
        &["tenant_id", "shard_id", "timeline_id"]
    )
    .expect("failed to define a metric")
@@ -545,6 +560,15 @@ static AUX_FILE_SIZE: Lazy<IntGaugeVec> = Lazy::new(|| {
    .expect("failed to define a metric")
 });

+static VALID_LSN_LEASE_COUNT: Lazy<UIntGaugeVec> = Lazy::new(|| {
+    register_uint_gauge_vec!(
+        "pageserver_valid_lsn_lease_count",
+        "The number of valid leases after refreshing gc info.",
+        &["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;
@@ -1070,21 +1094,12 @@ pub(crate) mod virtual_file_io_engine {
    });
 }

-#[derive(Debug)]
-struct GlobalAndPerTimelineHistogram {
-    global: Histogram,
-    per_tenant_timeline: Histogram,
-}
-
-impl GlobalAndPerTimelineHistogram {
-    fn observe(&self, value: f64) {
-        self.global.observe(value);
-        self.per_tenant_timeline.observe(value);
-    }
-}
-
 struct GlobalAndPerTimelineHistogramTimer<'a, 'c> {
-    h: &'a GlobalAndPerTimelineHistogram,
+    global_metric: &'a Histogram,
+
+    // Optional because not all op types are tracked per-timeline
+    timeline_metric: Option<&'a Histogram>,
+
    ctx: &'c RequestContext,
    start: std::time::Instant,
    op: SmgrQueryType,
@@ -1115,7 +1130,10 @@ impl<'a, 'c> Drop for GlobalAndPerTimelineHistogramTimer<'a, 'c> {
                elapsed
            }
        };
-        self.h.observe(ex_throttled.as_secs_f64());
+        self.global_metric.observe(ex_throttled.as_secs_f64());
+        if let Some(timeline_metric) = self.timeline_metric {
+            timeline_metric.observe(ex_throttled.as_secs_f64());
+        }
    }
 }

@@ -1140,7 +1158,8 @@ pub enum SmgrQueryType {

 #[derive(Debug)]
 pub(crate) struct SmgrQueryTimePerTimeline {
-    metrics: [GlobalAndPerTimelineHistogram; SmgrQueryType::COUNT],
+    global_metrics: [Histogram; SmgrQueryType::COUNT],
+    per_timeline_getpage: Histogram,
 }

 static SMGR_QUERY_TIME_PER_TENANT_TIMELINE: Lazy<HistogramVec> = Lazy::new(|| {
@@ -1218,27 +1237,32 @@ impl SmgrQueryTimePerTimeline {
        let tenant_id = tenant_shard_id.tenant_id.to_string();
        let shard_slug = format!("{}", tenant_shard_id.shard_slug());
        let timeline_id = timeline_id.to_string();
-        let metrics = std::array::from_fn(|i| {
+        let global_metrics = std::array::from_fn(|i| {
            let op = SmgrQueryType::from_repr(i).unwrap();
-            let global = SMGR_QUERY_TIME_GLOBAL
+            SMGR_QUERY_TIME_GLOBAL
                .get_metric_with_label_values(&[op.into()])
-                .unwrap();
-            let per_tenant_timeline = SMGR_QUERY_TIME_PER_TENANT_TIMELINE
-                .get_metric_with_label_values(&[op.into(), &tenant_id, &shard_slug, &timeline_id])
-                .unwrap();
-            GlobalAndPerTimelineHistogram {
-                global,
-                per_tenant_timeline,
-            }
+                .unwrap()
        });
-        Self { metrics }
+
+        let per_timeline_getpage = SMGR_QUERY_TIME_PER_TENANT_TIMELINE
+            .get_metric_with_label_values(&[
+                SmgrQueryType::GetPageAtLsn.into(),
+                &tenant_id,
+                &shard_slug,
+                &timeline_id,
+            ])
+            .unwrap();
+        Self {
+            global_metrics,
+            per_timeline_getpage,
+        }
    }
    pub(crate) fn start_timer<'c: 'a, 'a>(
        &'a self,
        op: SmgrQueryType,
        ctx: &'c RequestContext,
-    ) -> impl Drop + '_ {
-        let metric = &self.metrics[op as usize];
+    ) -> Option<impl Drop + '_> {
+        let global_metric = &self.global_metrics[op as usize];
        let start = Instant::now();
        match ctx.micros_spent_throttled.open() {
            Ok(()) => (),
@@ -1257,12 +1281,20 @@ impl SmgrQueryTimePerTimeline {
                });
            }
        }
-        GlobalAndPerTimelineHistogramTimer {
-            h: metric,
+
+        let timeline_metric = if matches!(op, SmgrQueryType::GetPageAtLsn) {
+            Some(&self.per_timeline_getpage)
+        } else {
+            None
+        };
+
+        Some(GlobalAndPerTimelineHistogramTimer {
+            global_metric,
+            timeline_metric,
            ctx,
            start,
            op,
-        }
+        })
    }
 }

@@ -1309,17 +1341,9 @@ mod smgr_query_time_tests {
            let get_counts = || {
                let global: u64 = ops
                    .iter()
-                    .map(|op| metrics.metrics[*op as usize].global.get_sample_count())
+                    .map(|op| metrics.global_metrics[*op as usize].get_sample_count())
                    .sum();
-                let per_tenant_timeline: u64 = ops
-                    .iter()
-                    .map(|op| {
-                        metrics.metrics[*op as usize]
-                            .per_tenant_timeline
-                            .get_sample_count()
-                    })
-                    .sum();
-                (global, per_tenant_timeline)
+                (global, metrics.per_timeline_getpage.get_sample_count())
            };

            let (pre_global, pre_per_tenant_timeline) = get_counts();
@@ -1330,7 +1354,12 @@ mod smgr_query_time_tests {
            drop(timer);

            let (post_global, post_per_tenant_timeline) = get_counts();
-            assert_eq!(post_per_tenant_timeline, 1);
+            if matches!(op, super::SmgrQueryType::GetPageAtLsn) {
+                // getpage ops are tracked per-timeline, others aren't
+                assert_eq!(post_per_tenant_timeline, 1);
+            } else {
+                assert_eq!(post_per_tenant_timeline, 0);
+            }
            assert!(post_global > pre_global);
        }
    }
@@ -1427,15 +1456,56 @@ impl<'a, 'c> BasebackupQueryTimeOngoingRecording<'a, 'c> {
    }
 }

-pub(crate) static LIVE_CONNECTIONS_COUNT: Lazy<IntGaugeVec> = Lazy::new(|| {
-    register_int_gauge_vec!(
-        "pageserver_live_connections",
-        "Number of live network connections",
+pub(crate) static LIVE_CONNECTIONS: Lazy<IntCounterPairVec> = Lazy::new(|| {
+    register_int_counter_pair_vec!(
+        "pageserver_live_connections_started",
+        "Number of network connections that we started handling",
+        "pageserver_live_connections_finished",
+        "Number of network connections that we finished handling",
        &["pageserver_connection_kind"]
    )
    .expect("failed to define a metric")
 });

+#[derive(Clone, Copy, enum_map::Enum, IntoStaticStr)]
+pub(crate) enum ComputeCommandKind {
+    PageStreamV2,
+    PageStream,
+    Basebackup,
+    Fullbackup,
+    ImportBasebackup,
+    ImportWal,
+    LeaseLsn,
+    Show,
+}
+
+pub(crate) struct ComputeCommandCounters {
+    map: EnumMap<ComputeCommandKind, IntCounter>,
+}
+
+pub(crate) static COMPUTE_COMMANDS_COUNTERS: Lazy<ComputeCommandCounters> = Lazy::new(|| {
+    let inner = register_int_counter_vec!(
+        "pageserver_compute_commands",
+        "Number of compute -> pageserver commands processed",
+        &["command"]
+    )
+    .expect("failed to define a metric");
+
+    ComputeCommandCounters {
+        map: EnumMap::from_array(std::array::from_fn(|i| {
+            let command = <ComputeCommandKind as enum_map::Enum>::from_usize(i);
+            let command_str: &'static str = command.into();
+            inner.with_label_values(&[command_str])
+        })),
+    }
+});
+
+impl ComputeCommandCounters {
+    pub(crate) fn for_command(&self, command: ComputeCommandKind) -> &IntCounter {
+        &self.map[command]
+    }
+}
+
 // remote storage metrics

 static REMOTE_TIMELINE_CLIENT_CALLS: Lazy<IntCounterPairVec> = Lazy::new(|| {
@@ -1645,6 +1715,15 @@ pub(crate) static SECONDARY_MODE: Lazy<SecondaryModeMetrics> = Lazy::new(|| {
 }
 });

+pub(crate) static SECONDARY_RESIDENT_PHYSICAL_SIZE: Lazy<UIntGaugeVec> = Lazy::new(|| {
+    register_uint_gauge_vec!(
+        "pageserver_secondary_resident_physical_size",
+        "The size of the layer files present in the pageserver's filesystem, for secondary locations.",
+        &["tenant_id", "shard_id"]
+    )
+    .expect("failed to define a metric")
+});
+
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
 pub enum RemoteOpKind {
    Upload,
@@ -2047,6 +2126,8 @@ pub(crate) struct TimelineMetrics {
    pub garbage_collect_histo: StorageTimeMetrics,
    pub find_gc_cutoffs_histo: StorageTimeMetrics,
    pub last_record_gauge: IntGauge,
+    pub pitr_history_size: UIntGauge,
+    pub archival_size: UIntGauge,
    pub standby_horizon_gauge: IntGauge,
    pub resident_physical_size_gauge: UIntGauge,
    /// copy of LayeredTimeline.current_logical_size
@@ -2055,6 +2136,8 @@ pub(crate) struct TimelineMetrics {
    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>,
+    /// Number of valid LSN leases.
+    pub valid_lsn_lease_count_gauge: UIntGauge,
    shutdown: std::sync::atomic::AtomicBool,
 }

@@ -2118,6 +2201,15 @@ impl TimelineMetrics {
        let last_record_gauge = LAST_RECORD_LSN
            .get_metric_with_label_values(&[&tenant_id, &shard_id, &timeline_id])
            .unwrap();
+
+        let pitr_history_size = PITR_HISTORY_SIZE
+            .get_metric_with_label_values(&[&tenant_id, &shard_id, &timeline_id])
+            .unwrap();
+
+        let archival_size = TIMELINE_ARCHIVE_SIZE
+            .get_metric_with_label_values(&[&tenant_id, &shard_id, &timeline_id])
+            .unwrap();
+
        let standby_horizon_gauge = STANDBY_HORIZON
            .get_metric_with_label_values(&[&tenant_id, &shard_id, &timeline_id])
            .unwrap();
@@ -2153,6 +2245,10 @@ impl TimelineMetrics {
        let evictions_with_low_residence_duration = evictions_with_low_residence_duration_builder
            .build(&tenant_id, &shard_id, &timeline_id);

+        let valid_lsn_lease_count_gauge = VALID_LSN_LEASE_COUNT
+            .get_metric_with_label_values(&[&tenant_id, &shard_id, &timeline_id])
+            .unwrap();
+
        TimelineMetrics {
            tenant_id,
            shard_id,
@@ -2166,6 +2262,8 @@ impl TimelineMetrics {
            find_gc_cutoffs_histo,
            load_layer_map_histo,
            last_record_gauge,
+            pitr_history_size,
+            archival_size,
            standby_horizon_gauge,
            resident_physical_size_gauge,
            current_logical_size_gauge,
@@ -2175,6 +2273,7 @@ impl TimelineMetrics {
            evictions_with_low_residence_duration: std::sync::RwLock::new(
                evictions_with_low_residence_duration,
            ),
+            valid_lsn_lease_count_gauge,
            shutdown: std::sync::atomic::AtomicBool::default(),
        }
    }
@@ -2222,8 +2321,13 @@ impl TimelineMetrics {
        if let Some(metric) = Lazy::get(&DIRECTORY_ENTRIES_COUNT) {
            let _ = metric.remove_label_values(&[tenant_id, shard_id, timeline_id]);
        }
+
+        let _ = TIMELINE_ARCHIVE_SIZE.remove_label_values(&[tenant_id, shard_id, timeline_id]);
+        let _ = PITR_HISTORY_SIZE.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]);
+        let _ = VALID_LSN_LEASE_COUNT.remove_label_values(&[tenant_id, shard_id, timeline_id]);

        self.evictions_with_low_residence_duration
            .write()
@@ -2254,14 +2358,12 @@ impl TimelineMetrics {
            let _ = STORAGE_IO_SIZE.remove_label_values(&[op, tenant_id, shard_id, timeline_id]);
        }

-        for op in SmgrQueryType::iter() {
-            let _ = SMGR_QUERY_TIME_PER_TENANT_TIMELINE.remove_label_values(&[
-                op.into(),
-                tenant_id,
-                shard_id,
-                timeline_id,
-            ]);
-        }
+        let _ = SMGR_QUERY_TIME_PER_TENANT_TIMELINE.remove_label_values(&[
+            SmgrQueryType::GetPageAtLsn.into(),
+            tenant_id,
+            shard_id,
+            timeline_id,
+        ]);
    }
 }

@@ -2932,4 +3034,5 @@ pub fn preinitialize_metrics() {
    Lazy::force(&RECONSTRUCT_TIME);
    Lazy::force(&tenant_throttling::TIMELINE_GET);
    Lazy::force(&BASEBACKUP_QUERY_TIME);
+    Lazy::force(&COMPUTE_COMMANDS_COUNTERS);
 }
--- a/pageserver/src/page_service.rs
+++ b/pageserver/src/page_service.rs
@@ -55,7 +55,7 @@ use crate::basebackup::BasebackupError;
 use crate::context::{DownloadBehavior, RequestContext};
 use crate::import_datadir::import_wal_from_tar;
 use crate::metrics;
-use crate::metrics::LIVE_CONNECTIONS_COUNT;
+use crate::metrics::{ComputeCommandKind, COMPUTE_COMMANDS_COUNTERS, LIVE_CONNECTIONS};
 use crate::pgdatadir_mapping::Version;
 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;
@@ -215,14 +215,9 @@ async fn page_service_conn_main(
    auth_type: AuthType,
    connection_ctx: RequestContext,
 ) -> anyhow::Result<()> {
-    // Immediately increment the gauge, then create a job to decrement it on task exit.
-    // One of the pros of `defer!` is that this will *most probably*
-    // get called, even in presence of panics.
-    let gauge = LIVE_CONNECTIONS_COUNT.with_label_values(&["page_service"]);
-    gauge.inc();
-    scopeguard::defer! {
-        gauge.dec();
-    }
+    let _guard = LIVE_CONNECTIONS
+        .with_label_values(&["page_service"])
+        .guard();

    socket
        .set_nodelay(true)
@@ -1554,6 +1549,10 @@ where

            self.check_permission(Some(tenant_id))?;

+            COMPUTE_COMMANDS_COUNTERS
+                .for_command(ComputeCommandKind::PageStreamV2)
+                .inc();
+
            self.handle_pagerequests(
                pgb,
                tenant_id,
@@ -1579,6 +1578,10 @@ where

            self.check_permission(Some(tenant_id))?;

+            COMPUTE_COMMANDS_COUNTERS
+                .for_command(ComputeCommandKind::PageStream)
+                .inc();
+
            self.handle_pagerequests(
                pgb,
                tenant_id,
@@ -1605,6 +1608,10 @@ where

            self.check_permission(Some(tenant_id))?;

+            COMPUTE_COMMANDS_COUNTERS
+                .for_command(ComputeCommandKind::Basebackup)
+                .inc();
+
            let lsn = if let Some(lsn_str) = params.get(2) {
                Some(
                    Lsn::from_str(lsn_str)
@@ -1644,48 +1651,6 @@ where
            metric_recording.observe(&res);
            res?;
        }
-        // return pair of prev_lsn and last_lsn
-        else if let Some(params) = parts.strip_prefix(&["get_last_record_rlsn"]) {
-            if params.len() != 2 {
-                return Err(QueryError::Other(anyhow::anyhow!(
-                    "invalid param number for get_last_record_rlsn command"
-                )));
-            }
-
-            let tenant_id = TenantId::from_str(params[0])
-                .with_context(|| format!("Failed to parse tenant id from {}", params[0]))?;
-            let timeline_id = TimelineId::from_str(params[1])
-                .with_context(|| format!("Failed to parse timeline id from {}", params[1]))?;
-
-            tracing::Span::current()
-                .record("tenant_id", field::display(tenant_id))
-                .record("timeline_id", field::display(timeline_id));
-
-            self.check_permission(Some(tenant_id))?;
-            async {
-                let timeline = self
-                    .get_active_tenant_timeline(tenant_id, timeline_id, ShardSelector::Zero)
-                    .await?;
-
-                let end_of_timeline = timeline.get_last_record_rlsn();
-
-                pgb.write_message_noflush(&BeMessage::RowDescription(&[
-                    RowDescriptor::text_col(b"prev_lsn"),
-                    RowDescriptor::text_col(b"last_lsn"),
-                ]))?
-                .write_message_noflush(&BeMessage::DataRow(&[
-                    Some(end_of_timeline.prev.to_string().as_bytes()),
-                    Some(end_of_timeline.last.to_string().as_bytes()),
-                ]))?
-                .write_message_noflush(&BeMessage::CommandComplete(b"SELECT 1"))?;
-                anyhow::Ok(())
-            }
-            .instrument(info_span!(
-                "handle_get_last_record_lsn",
-                shard_id = tracing::field::Empty
-            ))
-            .await?;
-        }
        // same as basebackup, but result includes relational data as well
        else if let Some(params) = parts.strip_prefix(&["fullbackup"]) {
            if params.len() < 2 {
@@ -1723,6 +1688,10 @@ where

            self.check_permission(Some(tenant_id))?;

+            COMPUTE_COMMANDS_COUNTERS
+                .for_command(ComputeCommandKind::Fullbackup)
+                .inc();
+
            // Check that the timeline exists
            self.handle_basebackup_request(
                pgb,
@@ -1771,6 +1740,10 @@ where

            self.check_permission(Some(tenant_id))?;

+            COMPUTE_COMMANDS_COUNTERS
+                .for_command(ComputeCommandKind::ImportBasebackup)
+                .inc();
+
            match self
                .handle_import_basebackup(
                    pgb,
@@ -1818,6 +1791,10 @@ where

            self.check_permission(Some(tenant_id))?;

+            COMPUTE_COMMANDS_COUNTERS
+                .for_command(ComputeCommandKind::ImportWal)
+                .inc();
+
            match self
                .handle_import_wal(pgb, tenant_id, timeline_id, start_lsn, end_lsn, ctx)
                .await
@@ -1855,6 +1832,10 @@ where

            self.check_permission(Some(tenant_shard_id.tenant_id))?;

+            COMPUTE_COMMANDS_COUNTERS
+                .for_command(ComputeCommandKind::LeaseLsn)
+                .inc();
+
            // The caller is responsible for providing correct lsn.
            let lsn = Lsn::from_str(params[2])
                .with_context(|| format!("Failed to parse Lsn from {}", params[2]))?;
@@ -1886,6 +1867,10 @@ where

            self.check_permission(Some(tenant_id))?;

+            COMPUTE_COMMANDS_COUNTERS
+                .for_command(ComputeCommandKind::Show)
+                .inc();
+
            let tenant = self
                .get_active_tenant_with_timeout(
                    tenant_id,
--- a/pageserver/src/tenant.rs
+++ b/pageserver/src/tenant.rs
--- a/pageserver/src/tenant/blob_io.rs
+++ b/pageserver/src/tenant/blob_io.rs
@@ -6,13 +6,20 @@
 //! is written as a one byte. If it's larger than that, the length
 //! is written as a four-byte integer, in big-endian, with the high
 //! bit set. This way, we can detect whether it's 1- or 4-byte header
-//! by peeking at the first byte.
+//! by peeking at the first byte. For blobs larger than 128 bits,
+//! we also specify three reserved bits, only one of the three bit
+//! patterns is currently in use (0b011) and signifies compression
+//! with zstd.
 //!
 //! len <  128: 0XXXXXXX
-//! len >= 128: 1XXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX
+//! len >= 128: 1CCCXXXX XXXXXXXX XXXXXXXX XXXXXXXX
 //!
+use async_compression::Level;
 use bytes::{BufMut, BytesMut};
+use pageserver_api::models::ImageCompressionAlgorithm;
+use tokio::io::AsyncWriteExt;
 use tokio_epoll_uring::{BoundedBuf, IoBuf, Slice};
+use tracing::warn;

 use crate::context::RequestContext;
 use crate::page_cache::PAGE_SZ;
@@ -66,12 +73,37 @@ impl<'a> BlockCursor<'a> {
                len_buf.copy_from_slice(&buf[off..off + 4]);
                off += 4;
            }
-            len_buf[0] &= 0x7f;
+            let bit_mask = if self.read_compressed {
+                !LEN_COMPRESSION_BIT_MASK
+            } else {
+                0x7f
+            };
+            len_buf[0] &= bit_mask;
            u32::from_be_bytes(len_buf) as usize
        };
+        let compression_bits = first_len_byte & LEN_COMPRESSION_BIT_MASK;

-        dstbuf.clear();
-        dstbuf.reserve(len);
+        let mut tmp_buf = Vec::new();
+        let buf_to_write;
+        let compression = if compression_bits <= BYTE_UNCOMPRESSED || !self.read_compressed {
+            if compression_bits > BYTE_UNCOMPRESSED {
+                warn!("reading key above future limit ({len} bytes)");
+            }
+            buf_to_write = dstbuf;
+            None
+        } else if compression_bits == BYTE_ZSTD {
+            buf_to_write = &mut tmp_buf;
+            Some(dstbuf)
+        } else {
+            let error = std::io::Error::new(
+                std::io::ErrorKind::InvalidData,
+                format!("invalid compression byte {compression_bits:x}"),
+            );
+            return Err(error);
+        };
+
+        buf_to_write.clear();
+        buf_to_write.reserve(len);

        // Read the payload
        let mut remain = len;
@@ -85,14 +117,35 @@ impl<'a> BlockCursor<'a> {
                page_remain = PAGE_SZ;
            }
            let this_blk_len = min(remain, page_remain);
-            dstbuf.extend_from_slice(&buf[off..off + this_blk_len]);
+            buf_to_write.extend_from_slice(&buf[off..off + this_blk_len]);
            remain -= this_blk_len;
            off += this_blk_len;
        }
+
+        if let Some(dstbuf) = compression {
+            if compression_bits == BYTE_ZSTD {
+                let mut decoder = async_compression::tokio::write::ZstdDecoder::new(dstbuf);
+                decoder.write_all(buf_to_write).await?;
+                decoder.flush().await?;
+            } else {
+                unreachable!("already checked above")
+            }
+        }
+
        Ok(())
    }
 }

+/// Reserved bits for length and compression
+const LEN_COMPRESSION_BIT_MASK: u8 = 0xf0;
+
+/// The maximum size of blobs we support. The highest few bits
+/// are reserved for compression and other further uses.
+const MAX_SUPPORTED_LEN: usize = 0x0fff_ffff;
+
+const BYTE_UNCOMPRESSED: u8 = 0x80;
+const BYTE_ZSTD: u8 = BYTE_UNCOMPRESSED | 0x10;
+
 /// A wrapper of `VirtualFile` that allows users to write blobs.
 ///
 /// If a `BlobWriter` is dropped, the internal buffer will be
@@ -219,6 +272,22 @@ impl<const BUFFERED: bool> BlobWriter<BUFFERED> {
        &mut self,
        srcbuf: B,
        ctx: &RequestContext,
+    ) -> (B::Buf, Result<u64, Error>) {
+        self.write_blob_maybe_compressed(
+            srcbuf,
+            ctx,
+            ImageCompressionAlgorithm::DisabledNoDecompress,
+        )
+        .await
+    }
+
+    /// Write a blob of data. Returns the offset that it was written to,
+    /// which can be used to retrieve the data later.
+    pub async fn write_blob_maybe_compressed<B: BoundedBuf<Buf = Buf>, Buf: IoBuf + Send>(
+        &mut self,
+        srcbuf: B,
+        ctx: &RequestContext,
+        algorithm: ImageCompressionAlgorithm,
    ) -> (B::Buf, Result<u64, Error>) {
        let offset = self.offset;

@@ -226,29 +295,61 @@ impl<const BUFFERED: bool> BlobWriter<BUFFERED> {

        let mut io_buf = self.io_buf.take().expect("we always put it back below");
        io_buf.clear();
-        let (io_buf, hdr_res) = async {
+        let mut compressed_buf = None;
+        let ((io_buf, hdr_res), srcbuf) = async {
            if len < 128 {
                // Short blob. Write a 1-byte length header
                io_buf.put_u8(len as u8);
-                self.write_all(io_buf, ctx).await
+                (
+                    self.write_all(io_buf, ctx).await,
+                    srcbuf.slice_full().into_inner(),
+                )
            } else {
                // Write a 4-byte length header
-                if len > 0x7fff_ffff {
+                if len > MAX_SUPPORTED_LEN {
                    return (
-                        io_buf,
-                        Err(Error::new(
-                            ErrorKind::Other,
-                            format!("blob too large ({len} bytes)"),
-                        )),
+                        (
+                            io_buf,
+                            Err(Error::new(
+                                ErrorKind::Other,
+                                format!("blob too large ({len} bytes)"),
+                            )),
+                        ),
+                        srcbuf.slice_full().into_inner(),
                    );
                }
-                if len > 0x0fff_ffff {
-                    tracing::warn!("writing blob above future limit ({len} bytes)");
-                }
-                let mut len_buf = (len as u32).to_be_bytes();
-                len_buf[0] |= 0x80;
+                let (high_bit_mask, len_written, srcbuf) = match algorithm {
+                    ImageCompressionAlgorithm::Zstd { level } => {
+                        let mut encoder = if let Some(level) = level {
+                            async_compression::tokio::write::ZstdEncoder::with_quality(
+                                Vec::new(),
+                                Level::Precise(level.into()),
+                            )
+                        } else {
+                            async_compression::tokio::write::ZstdEncoder::new(Vec::new())
+                        };
+                        let slice = srcbuf.slice_full();
+                        encoder.write_all(&slice[..]).await.unwrap();
+                        encoder.shutdown().await.unwrap();
+                        let compressed = encoder.into_inner();
+                        if compressed.len() < len {
+                            let compressed_len = compressed.len();
+                            compressed_buf = Some(compressed);
+                            (BYTE_ZSTD, compressed_len, slice.into_inner())
+                        } else {
+                            (BYTE_UNCOMPRESSED, len, slice.into_inner())
+                        }
+                    }
+                    ImageCompressionAlgorithm::Disabled
+                    | ImageCompressionAlgorithm::DisabledNoDecompress => {
+                        (BYTE_UNCOMPRESSED, len, srcbuf.slice_full().into_inner())
+                    }
+                };
+                let mut len_buf = (len_written as u32).to_be_bytes();
+                assert_eq!(len_buf[0] & 0xf0, 0);
+                len_buf[0] |= high_bit_mask;
                io_buf.extend_from_slice(&len_buf[..]);
-                self.write_all(io_buf, ctx).await
+                (self.write_all(io_buf, ctx).await, srcbuf)
            }
        }
        .await;
@@ -257,7 +358,12 @@ impl<const BUFFERED: bool> BlobWriter<BUFFERED> {
            Ok(_) => (),
            Err(e) => return (Slice::into_inner(srcbuf.slice(..)), Err(e)),
        }
-        let (srcbuf, res) = self.write_all(srcbuf, ctx).await;
+        let (srcbuf, res) = if let Some(compressed_buf) = compressed_buf {
+            let (_buf, res) = self.write_all(compressed_buf, ctx).await;
+            (Slice::into_inner(srcbuf.slice(..)), res)
+        } else {
+            self.write_all(srcbuf, ctx).await
+        };
        (srcbuf, res.map(|_| offset))
    }
 }
@@ -295,6 +401,13 @@ mod tests {
    use rand::{Rng, SeedableRng};

    async fn round_trip_test<const BUFFERED: bool>(blobs: &[Vec<u8>]) -> Result<(), Error> {
+        round_trip_test_compressed::<BUFFERED>(blobs, false).await
+    }
+
+    async fn round_trip_test_compressed<const BUFFERED: bool>(
+        blobs: &[Vec<u8>],
+        compression: bool,
+    ) -> Result<(), Error> {
        let temp_dir = camino_tempfile::tempdir()?;
        let pathbuf = temp_dir.path().join("file");
        let ctx = RequestContext::new(TaskKind::UnitTest, DownloadBehavior::Error);
@@ -305,7 +418,16 @@ mod tests {
            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(), &ctx).await;
+                let (_, res) = if compression {
+                    wtr.write_blob_maybe_compressed(
+                        blob.clone(),
+                        &ctx,
+                        ImageCompressionAlgorithm::Zstd { level: Some(1) },
+                    )
+                    .await
+                } else {
+                    wtr.write_blob(blob.clone(), &ctx).await
+                };
                let offs = res?;
                offsets.push(offs);
            }
@@ -319,7 +441,7 @@ mod tests {

        let file = VirtualFile::open(pathbuf.as_path(), &ctx).await?;
        let rdr = BlockReaderRef::VirtualFile(&file);
-        let rdr = BlockCursor::new(rdr);
+        let rdr = BlockCursor::new_with_compression(rdr, compression);
        for (idx, (blob, offset)) in blobs.iter().zip(offsets.iter()).enumerate() {
            let blob_read = rdr.read_blob(*offset, &ctx).await?;
            assert_eq!(
@@ -353,6 +475,8 @@ mod tests {
        ];
        round_trip_test::<false>(blobs).await?;
        round_trip_test::<true>(blobs).await?;
+        round_trip_test_compressed::<false>(blobs, true).await?;
+        round_trip_test_compressed::<true>(blobs, true).await?;
        Ok(())
    }

@@ -361,10 +485,15 @@ mod tests {
        let blobs = &[
            b"test".to_vec(),
            random_array(10 * PAGE_SZ),
+            b"hello".to_vec(),
+            random_array(66 * PAGE_SZ),
+            vec![0xf3; 24 * PAGE_SZ],
            b"foobar".to_vec(),
        ];
        round_trip_test::<false>(blobs).await?;
        round_trip_test::<true>(blobs).await?;
+        round_trip_test_compressed::<false>(blobs, true).await?;
+        round_trip_test_compressed::<true>(blobs, true).await?;
        Ok(())
    }

--- a/pageserver/src/tenant/block_io.rs
+++ b/pageserver/src/tenant/block_io.rs
@@ -37,6 +37,7 @@ where
 pub enum BlockLease<'a> {
    PageReadGuard(PageReadGuard<'static>),
    EphemeralFileMutableTail(&'a [u8; PAGE_SZ]),
+    Slice(&'a [u8; PAGE_SZ]),
    #[cfg(test)]
    Arc(std::sync::Arc<[u8; PAGE_SZ]>),
    #[cfg(test)]
@@ -63,6 +64,7 @@ impl<'a> Deref for BlockLease<'a> {
        match self {
            BlockLease::PageReadGuard(v) => v.deref(),
            BlockLease::EphemeralFileMutableTail(v) => v,
+            BlockLease::Slice(v) => v,
            #[cfg(test)]
            BlockLease::Arc(v) => v.deref(),
            #[cfg(test)]
@@ -81,6 +83,7 @@ pub(crate) enum BlockReaderRef<'a> {
    FileBlockReader(&'a FileBlockReader<'a>),
    EphemeralFile(&'a EphemeralFile),
    Adapter(Adapter<&'a DeltaLayerInner>),
+    Slice(&'a [u8]),
    #[cfg(test)]
    TestDisk(&'a super::disk_btree::tests::TestDisk),
    #[cfg(test)]
@@ -99,6 +102,7 @@ impl<'a> BlockReaderRef<'a> {
            FileBlockReader(r) => r.read_blk(blknum, ctx).await,
            EphemeralFile(r) => r.read_blk(blknum, ctx).await,
            Adapter(r) => r.read_blk(blknum, ctx).await,
+            Slice(s) => Self::read_blk_slice(s, blknum),
            #[cfg(test)]
            TestDisk(r) => r.read_blk(blknum),
            #[cfg(test)]
@@ -107,6 +111,24 @@ impl<'a> BlockReaderRef<'a> {
    }
 }

+impl<'a> BlockReaderRef<'a> {
+    fn read_blk_slice(slice: &[u8], blknum: u32) -> std::io::Result<BlockLease> {
+        let start = (blknum as usize).checked_mul(PAGE_SZ).unwrap();
+        let end = start.checked_add(PAGE_SZ).unwrap();
+        if end > slice.len() {
+            return Err(std::io::Error::new(
+                std::io::ErrorKind::UnexpectedEof,
+                format!("slice too short, len={} end={}", slice.len(), end),
+            ));
+        }
+        let slice = &slice[start..end];
+        let page_sized: &[u8; PAGE_SZ] = slice
+            .try_into()
+            .expect("we add PAGE_SZ to start, so the slice must have PAGE_SZ");
+        Ok(BlockLease::Slice(page_sized))
+    }
+}
+
 ///
 /// A "cursor" for efficiently reading multiple pages from a BlockReader
 ///
@@ -127,16 +149,24 @@ impl<'a> BlockReaderRef<'a> {
 /// ```
 ///
 pub struct BlockCursor<'a> {
+    pub(super) read_compressed: bool,
    reader: BlockReaderRef<'a>,
 }

 impl<'a> BlockCursor<'a> {
    pub(crate) fn new(reader: BlockReaderRef<'a>) -> Self {
-        BlockCursor { reader }
+        Self::new_with_compression(reader, false)
+    }
+    pub(crate) fn new_with_compression(reader: BlockReaderRef<'a>, read_compressed: bool) -> Self {
+        BlockCursor {
+            read_compressed,
+            reader,
+        }
    }
    // Needed by cli
    pub fn new_fileblockreader(reader: &'a FileBlockReader) -> Self {
        BlockCursor {
+            read_compressed: false,
            reader: BlockReaderRef::FileBlockReader(reader),
        }
    }
@@ -160,16 +190,31 @@ impl<'a> BlockCursor<'a> {
 ///
 /// The file is assumed to be immutable. This doesn't provide any functions
 /// for modifying the file, nor for invalidating the cache if it is modified.
+#[derive(Clone)]
 pub struct FileBlockReader<'a> {
    pub file: &'a VirtualFile,

    /// Unique ID of this file, used as key in the page cache.
    file_id: page_cache::FileId,
+
+    compressed_reads: bool,
 }

 impl<'a> FileBlockReader<'a> {
    pub fn new(file: &'a VirtualFile, file_id: FileId) -> Self {
-        FileBlockReader { file_id, file }
+        Self::new_with_compression(file, file_id, false)
+    }
+
+    pub fn new_with_compression(
+        file: &'a VirtualFile,
+        file_id: FileId,
+        compressed_reads: bool,
+    ) -> Self {
+        FileBlockReader {
+            file_id,
+            file,
+            compressed_reads,
+        }
    }

    /// Read a page from the underlying file into given buffer.
@@ -216,7 +261,10 @@ impl<'a> FileBlockReader<'a> {

 impl BlockReader for FileBlockReader<'_> {
    fn block_cursor(&self) -> BlockCursor<'_> {
-        BlockCursor::new(BlockReaderRef::FileBlockReader(self))
+        BlockCursor::new_with_compression(
+            BlockReaderRef::FileBlockReader(self),
+            self.compressed_reads,
+        )
    }
 }

--- a/pageserver/src/tenant/config.rs
+++ b/pageserver/src/tenant/config.rs
@@ -281,22 +281,6 @@ impl LocationConf {
    }
 }

-impl Default for LocationConf {
-    // TODO: this should be removed once tenant loading can guarantee that we are never
-    // loading from a directory without a configuration.
-    // => tech debt since https://github.com/neondatabase/neon/issues/1555
-    fn default() -> Self {
-        Self {
-            mode: LocationMode::Attached(AttachedLocationConfig {
-                generation: Generation::none(),
-                attach_mode: AttachmentMode::Single,
-            }),
-            tenant_conf: TenantConfOpt::default(),
-            shard: ShardIdentity::unsharded(),
-        }
-    }
-}
-
 /// A tenant's calcuated configuration, which is the result of merging a
 /// tenant's TenantConfOpt with the global TenantConf from PageServerConf.
 ///
--- a/pageserver/src/tenant/delete.rs
+++ b/pageserver/src/tenant/delete.rs
@@ -1,426 +0,0 @@
-use std::sync::Arc;
-
-use anyhow::Context;
-use camino::{Utf8Path, Utf8PathBuf};
-use pageserver_api::{models::TenantState, shard::TenantShardId};
-use remote_storage::{GenericRemoteStorage, RemotePath, TimeoutOrCancel};
-use tokio::sync::OwnedMutexGuard;
-use tokio_util::sync::CancellationToken;
-use tracing::{error, Instrument};
-
-use utils::{backoff, completion, crashsafe, fs_ext, id::TimelineId, pausable_failpoint};
-
-use crate::{
-    config::PageServerConf,
-    context::RequestContext,
-    task_mgr::{self},
-    tenant::{
-        mgr::{TenantSlot, TenantsMapRemoveResult},
-        remote_timeline_client::remote_heatmap_path,
-    },
-};
-
-use super::{
-    mgr::{GetTenantError, TenantSlotError, TenantSlotUpsertError, TenantsMap},
-    remote_timeline_client::{FAILED_REMOTE_OP_RETRIES, FAILED_UPLOAD_WARN_THRESHOLD},
-    timeline::delete::DeleteTimelineFlow,
-    tree_sort_timelines, DeleteTimelineError, Tenant, TenantPreload,
-};
-
-#[derive(Debug, thiserror::Error)]
-pub(crate) enum DeleteTenantError {
-    #[error("GetTenant {0}")]
-    Get(#[from] GetTenantError),
-
-    #[error("Tenant map slot error {0}")]
-    SlotError(#[from] TenantSlotError),
-
-    #[error("Tenant map slot upsert error {0}")]
-    SlotUpsertError(#[from] TenantSlotUpsertError),
-
-    #[error("Timeline {0}")]
-    Timeline(#[from] DeleteTimelineError),
-
-    #[error("Cancelled")]
-    Cancelled,
-
-    #[error(transparent)]
-    Other(#[from] anyhow::Error),
-}
-
-type DeletionGuard = tokio::sync::OwnedMutexGuard<DeleteTenantFlow>;
-
-fn remote_tenant_delete_mark_path(
-    conf: &PageServerConf,
-    tenant_shard_id: &TenantShardId,
-) -> anyhow::Result<RemotePath> {
-    let tenant_remote_path = conf
-        .tenant_path(tenant_shard_id)
-        .strip_prefix(&conf.workdir)
-        .context("Failed to strip workdir prefix")
-        .and_then(RemotePath::new)
-        .context("tenant path")?;
-    Ok(tenant_remote_path.join(Utf8Path::new("timelines/deleted")))
-}
-
-async fn schedule_ordered_timeline_deletions(
-    tenant: &Arc<Tenant>,
-) -> Result<Vec<(Arc<tokio::sync::Mutex<DeleteTimelineFlow>>, TimelineId)>, DeleteTenantError> {
-    // Tenant is stopping at this point. We know it will be deleted.
-    // No new timelines should be created.
-    // Tree sort timelines to delete from leafs to the root.
-    // NOTE: by calling clone we release the mutex which creates a possibility for a race: pending deletion
-    // can complete and remove timeline from the map in between our call to clone
-    // and `DeleteTimelineFlow::run`, so `run` wont find timeline in `timelines` map.
-    // timelines.lock is currently synchronous so we cant hold it across await point.
-    // So just ignore NotFound error if we get it from `run`.
-    // Beware: in case it becomes async and we try to hold it here, `run` also locks it, which can create a deadlock.
-    let timelines = tenant.timelines.lock().unwrap().clone();
-    let sorted =
-        tree_sort_timelines(timelines, |t| t.get_ancestor_timeline_id()).context("tree sort")?;
-
-    let mut already_running_deletions = vec![];
-
-    for (timeline_id, _) in sorted.into_iter().rev() {
-        let span = tracing::info_span!("timeline_delete", %timeline_id);
-        let res = DeleteTimelineFlow::run(tenant, timeline_id, true)
-            .instrument(span)
-            .await;
-        if let Err(e) = res {
-            match e {
-                DeleteTimelineError::NotFound => {
-                    // Timeline deletion finished after call to clone above but before call
-                    // to `DeleteTimelineFlow::run` and removed timeline from the map.
-                    continue;
-                }
-                DeleteTimelineError::AlreadyInProgress(guard) => {
-                    already_running_deletions.push((guard, timeline_id));
-                    continue;
-                }
-                e => return Err(DeleteTenantError::Timeline(e)),
-            }
-        }
-    }
-
-    Ok(already_running_deletions)
-}
-
-async fn ensure_timelines_dir_empty(timelines_path: &Utf8Path) -> Result<(), DeleteTenantError> {
-    // Assert timelines dir is empty.
-    if !fs_ext::is_directory_empty(timelines_path).await? {
-        // Display first 10 items in directory
-        let list = fs_ext::list_dir(timelines_path).await.context("list_dir")?;
-        let list = &list.into_iter().take(10).collect::<Vec<_>>();
-        return Err(DeleteTenantError::Other(anyhow::anyhow!(
-            "Timelines directory is not empty after all timelines deletion: {list:?}"
-        )));
-    }
-
-    Ok(())
-}
-
-async fn remove_tenant_remote_delete_mark(
-    conf: &PageServerConf,
-    remote_storage: &GenericRemoteStorage,
-    tenant_shard_id: &TenantShardId,
-    cancel: &CancellationToken,
-) -> Result<(), DeleteTenantError> {
-    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(())
-}
-
-// Cleanup fs traces: tenant config, timelines dir local delete mark, tenant dir
-async fn cleanup_remaining_fs_traces(
-    conf: &PageServerConf,
-    tenant_shard_id: &TenantShardId,
-) -> Result<(), DeleteTenantError> {
-    let rm = |p: Utf8PathBuf, is_dir: bool| async move {
-        if is_dir {
-            tokio::fs::remove_dir(&p).await
-        } else {
-            tokio::fs::remove_file(&p).await
-        }
-        .or_else(fs_ext::ignore_not_found)
-        .with_context(|| format!("failed to delete {p}"))
-    };
-
-    rm(conf.tenant_config_path(tenant_shard_id), false).await?;
-    rm(conf.tenant_location_config_path(tenant_shard_id), false).await?;
-
-    fail::fail_point!("tenant-delete-before-remove-timelines-dir", |_| {
-        Err(anyhow::anyhow!(
-            "failpoint: tenant-delete-before-remove-timelines-dir"
-        ))?
-    });
-
-    rm(conf.timelines_path(tenant_shard_id), true).await?;
-
-    fail::fail_point!("tenant-delete-before-remove-deleted-mark", |_| {
-        Err(anyhow::anyhow!(
-            "failpoint: tenant-delete-before-remove-deleted-mark"
-        ))?
-    });
-
-    // Make sure previous deletions are ordered before mark removal.
-    // Otherwise there is no guarantee that they reach the disk before mark deletion.
-    // So its possible for mark to reach disk first and for other deletions
-    // to be reordered later and thus missed if a crash occurs.
-    // Note that we dont need to sync after mark file is removed
-    // because we can tolerate the case when mark file reappears on startup.
-    let tenant_path = &conf.tenant_path(tenant_shard_id);
-    if tenant_path.exists() {
-        crashsafe::fsync_async(&conf.tenant_path(tenant_shard_id))
-            .await
-            .context("fsync_pre_mark_remove")?;
-    }
-
-    rm(conf.tenant_deleted_mark_file_path(tenant_shard_id), false).await?;
-
-    rm(conf.tenant_heatmap_path(tenant_shard_id), false).await?;
-
-    fail::fail_point!("tenant-delete-before-remove-tenant-dir", |_| {
-        Err(anyhow::anyhow!(
-            "failpoint: tenant-delete-before-remove-tenant-dir"
-        ))?
-    });
-
-    rm(conf.tenant_path(tenant_shard_id), true).await?;
-
-    Ok(())
-}
-
-#[derive(Default)]
-pub enum DeleteTenantFlow {
-    #[default]
-    NotStarted,
-    InProgress,
-    Finished,
-}
-
-impl DeleteTenantFlow {
-    pub(crate) async fn should_resume_deletion(
-        conf: &'static PageServerConf,
-        remote_mark_exists: bool,
-        tenant: &Tenant,
-    ) -> Result<Option<DeletionGuard>, DeleteTenantError> {
-        let acquire = |t: &Tenant| {
-            Some(
-                Arc::clone(&t.delete_progress)
-                    .try_lock_owned()
-                    .expect("we're the only owner during init"),
-            )
-        };
-
-        if remote_mark_exists {
-            return Ok(acquire(tenant));
-        }
-
-        // Check local mark first, if its there there is no need to go to s3 to check whether remote one exists.
-        if conf
-            .tenant_deleted_mark_file_path(&tenant.tenant_shard_id)
-            .exists()
-        {
-            Ok(acquire(tenant))
-        } else {
-            Ok(None)
-        }
-    }
-
-    pub(crate) async fn resume_from_attach(
-        guard: DeletionGuard,
-        tenant: &Arc<Tenant>,
-        preload: Option<TenantPreload>,
-        tenants: &'static std::sync::RwLock<TenantsMap>,
-        ctx: &RequestContext,
-    ) -> Result<(), DeleteTenantError> {
-        let (_, progress) = completion::channel();
-
-        tenant
-            .set_stopping(progress, false, true)
-            .await
-            .expect("cant be stopping or broken");
-
-        tenant
-            .attach(preload, super::SpawnMode::Eager, ctx)
-            .await
-            .context("attach")?;
-
-        Self::background(
-            guard,
-            tenant.conf,
-            tenant.remote_storage.clone(),
-            tenants,
-            tenant,
-        )
-        .await
-    }
-
-    async fn background(
-        mut guard: OwnedMutexGuard<Self>,
-        conf: &PageServerConf,
-        remote_storage: GenericRemoteStorage,
-        tenants: &'static std::sync::RwLock<TenantsMap>,
-        tenant: &Arc<Tenant>,
-    ) -> Result<(), DeleteTenantError> {
-        // Tree sort timelines, schedule delete for them. Mention retries from the console side.
-        // Note that if deletion fails we dont mark timelines as broken,
-        // the whole tenant will become broken as by `Self::schedule_background` logic
-        let already_running_timeline_deletions = schedule_ordered_timeline_deletions(tenant)
-            .await
-            .context("schedule_ordered_timeline_deletions")?;
-
-        fail::fail_point!("tenant-delete-before-polling-ongoing-deletions", |_| {
-            Err(anyhow::anyhow!(
-                "failpoint: tenant-delete-before-polling-ongoing-deletions"
-            ))?
-        });
-
-        // Wait for deletions that were already running at the moment when tenant deletion was requested.
-        // When we can lock deletion guard it means that corresponding timeline deletion finished.
-        for (guard, timeline_id) in already_running_timeline_deletions {
-            let flow = guard.lock().await;
-            if !flow.is_finished() {
-                return Err(DeleteTenantError::Other(anyhow::anyhow!(
-                    "already running timeline deletion failed: {timeline_id}"
-                )));
-            }
-        }
-
-        // Remove top-level tenant objects that don't belong to a timeline, such as heatmap
-        let heatmap_path = remote_heatmap_path(&tenant.tenant_shard_id());
-        if let Some(Err(e)) = backoff::retry(
-            || async {
-                remote_storage
-                    .delete(&heatmap_path, &task_mgr::shutdown_token())
-                    .await
-            },
-            TimeoutOrCancel::caused_by_cancel,
-            FAILED_UPLOAD_WARN_THRESHOLD,
-            FAILED_REMOTE_OP_RETRIES,
-            "remove_remote_tenant_heatmap",
-            &task_mgr::shutdown_token(),
-        )
-        .await
-        {
-            tracing::warn!("Failed to delete heatmap at {heatmap_path}: {e}");
-        }
-
-        let timelines_path = conf.timelines_path(&tenant.tenant_shard_id);
-        // May not exist if we fail in cleanup_remaining_fs_traces after removing it
-        if timelines_path.exists() {
-            // sanity check to guard against layout changes
-            ensure_timelines_dir_empty(&timelines_path)
-                .await
-                .context("timelines dir not empty")?;
-        }
-
-        remove_tenant_remote_delete_mark(
-            conf,
-            &remote_storage,
-            &tenant.tenant_shard_id,
-            &task_mgr::shutdown_token(),
-        )
-        .await?;
-
-        pausable_failpoint!("tenant-delete-before-cleanup-remaining-fs-traces-pausable");
-        fail::fail_point!("tenant-delete-before-cleanup-remaining-fs-traces", |_| {
-            Err(anyhow::anyhow!(
-                "failpoint: tenant-delete-before-cleanup-remaining-fs-traces"
-            ))?
-        });
-
-        cleanup_remaining_fs_traces(conf, &tenant.tenant_shard_id)
-            .await
-            .context("cleanup_remaining_fs_traces")?;
-
-        {
-            // This block is simply removing the TenantSlot for this tenant.  It requires a loop because
-            // we might conflict with a TenantSlot::InProgress marker and need to wait for it.
-            //
-            // This complexity will go away when we simplify how deletion works:
-            // https://github.com/neondatabase/neon/issues/5080
-            loop {
-                // Under the TenantMap lock, try to remove the tenant.  We usually succeed, but if
-                // we encounter an InProgress marker, yield the barrier it contains and wait on it.
-                let barrier = {
-                    let mut locked = tenants.write().unwrap();
-                    let removed = locked.remove(tenant.tenant_shard_id);
-
-                    // 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)
-
-                    // 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)) => {
-                            match tenant.current_state() {
-                                TenantState::Stopping { .. } | TenantState::Broken { .. } => {
-                                    // Expected: we put the tenant into stopping state before we start deleting it
-                                }
-                                state => {
-                                    // Unexpected state
-                                    tracing::warn!(
-                                        "Tenant in unexpected state {state} after deletion"
-                                    );
-                                }
-                            }
-                            break;
-                        }
-                        TenantsMapRemoveResult::Occupied(TenantSlot::Secondary(_)) => {
-                            // This is unexpected: this secondary tenants should not have been created, and we
-                            // are not in a position to shut it down from here.
-                            tracing::warn!("Tenant transitioned to secondary mode while deleting!");
-                            break;
-                        }
-                        TenantsMapRemoveResult::Occupied(TenantSlot::InProgress(_)) => {
-                            unreachable!("TenantsMap::remove handles InProgress separately, should never return it here");
-                        }
-                        TenantsMapRemoveResult::Vacant => {
-                            tracing::warn!(
-                                "Tenant removed from TenantsMap before deletion completed"
-                            );
-                            break;
-                        }
-                        TenantsMapRemoveResult::InProgress(barrier) => {
-                            // An InProgress entry was found, we must wait on its barrier
-                            barrier
-                        }
-                    }
-                };
-
-                tracing::info!(
-                    "Waiting for competing operation to complete before deleting state for tenant"
-                );
-                barrier.wait().await;
-            }
-        }
-
-        *guard = Self::Finished;
-
-        Ok(())
-    }
-}
--- a/pageserver/src/tenant/disk_btree.rs
+++ b/pageserver/src/tenant/disk_btree.rs
@@ -212,6 +212,7 @@ impl<'a, const L: usize> OnDiskNode<'a, L> {
 ///
 /// Public reader object, to search the tree.
 ///
+#[derive(Clone)]
 pub struct DiskBtreeReader<R, const L: usize>
 where
    R: BlockReader,
@@ -259,27 +260,38 @@ where
        Ok(result)
    }

-    pub fn iter<'a>(
-        &'a self,
-        start_key: &'a [u8; L],
-        ctx: &'a RequestContext,
-    ) -> DiskBtreeIterator<'a> {
+    pub fn iter<'a>(self, start_key: &'a [u8; L], ctx: &'a RequestContext) -> DiskBtreeIterator<'a>
+    where
+        R: 'a,
+    {
        DiskBtreeIterator {
-            stream: Box::pin(self.get_stream_from(start_key, ctx)),
+            stream: Box::pin(self.into_stream(start_key, ctx)),
        }
    }

    /// Return a stream which yields all key, value pairs from the index
    /// starting from the first key greater or equal to `start_key`.
    ///
-    /// Note that this is a copy of [`Self::visit`].
+    /// Note 1: that this is a copy of [`Self::visit`].
    /// TODO: Once the sequential read path is removed this will become
    /// the only index traversal method.
-    pub fn get_stream_from<'a>(
-        &'a self,
+    ///
+    /// Note 2: this function used to take `&self` but it now consumes `self`. This is due to
+    /// the lifetime constraints of the reader and the stream / iterator it creates. Using `&self`
+    /// requires the reader to be present when the stream is used, and this creates a lifetime
+    /// dependency between the reader and the stream. Now if we want to create an iterator that
+    /// holds the stream, someone will need to keep a reference to the reader, which is inconvenient
+    /// to use from the image/delta layer APIs.
+    ///
+    /// Feel free to add the `&self` variant back if it's necessary.
+    pub fn into_stream<'a>(
+        self,
        start_key: &'a [u8; L],
        ctx: &'a RequestContext,
-    ) -> impl Stream<Item = std::result::Result<(Vec<u8>, u64), DiskBtreeError>> + 'a {
+    ) -> impl Stream<Item = std::result::Result<(Vec<u8>, u64), DiskBtreeError>> + 'a
+    where
+        R: 'a,
+    {
        try_stream! {
            let mut stack = Vec::new();
            stack.push((self.root_blk, None));
--- a/pageserver/src/tenant/ephemeral_file.rs
+++ b/pageserver/src/tenant/ephemeral_file.rs
@@ -21,6 +21,7 @@ pub struct EphemeralFile {
 }

 mod page_caching;
+pub(crate) use page_caching::PrewarmOnWrite as PrewarmPageCacheOnWrite;
 mod zero_padded_read_write;

 impl EphemeralFile {
@@ -53,7 +54,7 @@ impl EphemeralFile {
        Ok(EphemeralFile {
            _tenant_shard_id: tenant_shard_id,
            _timeline_id: timeline_id,
-            rw: page_caching::RW::new(file),
+            rw: page_caching::RW::new(file, conf.l0_flush.prewarm_on_write()),
        })
    }

@@ -65,6 +66,11 @@ impl EphemeralFile {
        self.rw.page_cache_file_id()
    }

+    /// See [`self::page_caching::RW::load_to_vec`].
+    pub(crate) async fn load_to_vec(&self, ctx: &RequestContext) -> Result<Vec<u8>, io::Error> {
+        self.rw.load_to_vec(ctx).await
+    }
+
    pub(crate) async fn read_blk(
        &self,
        blknum: u32,
--- a/pageserver/src/tenant/ephemeral_file/page_caching.rs
+++ b/pageserver/src/tenant/ephemeral_file/page_caching.rs
@@ -8,6 +8,7 @@ use crate::virtual_file::VirtualFile;

 use once_cell::sync::Lazy;
 use std::io::{self, ErrorKind};
+use std::ops::{Deref, Range};
 use tokio_epoll_uring::BoundedBuf;
 use tracing::*;

@@ -19,14 +20,23 @@ pub struct RW {
    rw: super::zero_padded_read_write::RW<PreWarmingWriter>,
 }

+/// When we flush a block to the underlying [`crate::virtual_file::VirtualFile`],
+/// should we pre-warm the [`crate::page_cache`] with the contents?
+#[derive(Clone, Copy)]
+pub enum PrewarmOnWrite {
+    Yes,
+    No,
+}
+
 impl RW {
-    pub fn new(file: VirtualFile) -> Self {
+    pub fn new(file: VirtualFile, prewarm_on_write: PrewarmOnWrite) -> Self {
        let page_cache_file_id = page_cache::next_file_id();
        Self {
            page_cache_file_id,
            rw: super::zero_padded_read_write::RW::new(PreWarmingWriter::new(
                page_cache_file_id,
                file,
+                prewarm_on_write,
            )),
        }
    }
@@ -49,6 +59,43 @@ impl RW {
        self.rw.bytes_written()
    }

+    /// Load all blocks that can be read via [`Self::read_blk`] into a contiguous memory buffer.
+    ///
+    /// This includes the blocks that aren't yet flushed to disk by the internal buffered writer.
+    /// The last block is zero-padded to [`PAGE_SZ`], so, the returned buffer is always a multiple of [`PAGE_SZ`].
+    pub(super) async fn load_to_vec(&self, ctx: &RequestContext) -> Result<Vec<u8>, io::Error> {
+        // round up to the next PAGE_SZ multiple, required by blob_io
+        let size = {
+            let s = usize::try_from(self.bytes_written()).unwrap();
+            if s % PAGE_SZ == 0 {
+                s
+            } else {
+                s.checked_add(PAGE_SZ - (s % PAGE_SZ)).unwrap()
+            }
+        };
+        let vec = Vec::with_capacity(size);
+
+        // read from disk what we've already flushed
+        let writer = self.rw.as_writer();
+        let flushed_range = writer.written_range();
+        let mut vec = writer
+            .file
+            .read_exact_at(
+                vec.slice(0..(flushed_range.end - flushed_range.start)),
+                u64::try_from(flushed_range.start).unwrap(),
+                ctx,
+            )
+            .await?
+            .into_inner();
+
+        // copy from in-memory buffer what we haven't flushed yet but would return when accessed via read_blk
+        let buffered = self.rw.get_tail_zero_padded();
+        vec.extend_from_slice(buffered);
+        assert_eq!(vec.len(), size);
+        assert_eq!(vec.len() % PAGE_SZ, 0);
+        Ok(vec)
+    }
+
    pub(crate) async fn read_blk(
        &self,
        blknum: u32,
@@ -116,19 +163,40 @@ impl Drop for RW {
 }

 struct PreWarmingWriter {
+    prewarm_on_write: PrewarmOnWrite,
    nwritten_blocks: u32,
    page_cache_file_id: page_cache::FileId,
    file: VirtualFile,
 }

 impl PreWarmingWriter {
-    fn new(page_cache_file_id: page_cache::FileId, file: VirtualFile) -> Self {
+    fn new(
+        page_cache_file_id: page_cache::FileId,
+        file: VirtualFile,
+        prewarm_on_write: PrewarmOnWrite,
+    ) -> Self {
        Self {
+            prewarm_on_write,
            nwritten_blocks: 0,
            page_cache_file_id,
            file,
        }
    }
+
+    /// Return the byte range within `file` that has been written though `write_all`.
+    ///
+    /// The returned range would be invalidated by another `write_all`. To prevent that, we capture `&_`.
+    fn written_range(&self) -> (impl Deref<Target = Range<usize>> + '_) {
+        let nwritten_blocks = usize::try_from(self.nwritten_blocks).unwrap();
+        struct Wrapper(Range<usize>);
+        impl Deref for Wrapper {
+            type Target = Range<usize>;
+            fn deref(&self) -> &Range<usize> {
+                &self.0
+            }
+        }
+        Wrapper(0..nwritten_blocks * PAGE_SZ)
+    }
 }

 impl crate::virtual_file::owned_buffers_io::write::OwnedAsyncWriter for PreWarmingWriter {
@@ -178,45 +246,51 @@ impl crate::virtual_file::owned_buffers_io::write::OwnedAsyncWriter for PreWarmi
            assert_eq!(&check_bounds_stuff_works, &*buf);
        }

-        // Pre-warm page cache with the contents.
-        // At least in isolated bulk ingest benchmarks (test_bulk_insert.py), the pre-warming
-        // benefits the code that writes InMemoryLayer=>L0 layers.
        let nblocks = buflen / PAGE_SZ;
        let nblocks32 = u32::try_from(nblocks).unwrap();
-        let cache = page_cache::get();
-        static CTX: Lazy<RequestContext> = Lazy::new(|| {
-            RequestContext::new(
-                crate::task_mgr::TaskKind::EphemeralFilePreWarmPageCache,
-                crate::context::DownloadBehavior::Error,
-            )
-        });
-        for blknum_in_buffer in 0..nblocks {
-            let blk_in_buffer = &buf[blknum_in_buffer * PAGE_SZ..(blknum_in_buffer + 1) * PAGE_SZ];
-            let blknum = self
-                .nwritten_blocks
-                .checked_add(blknum_in_buffer as u32)
-                .unwrap();
-            match cache
-                .read_immutable_buf(self.page_cache_file_id, blknum, &CTX)
-                .await
-            {
-                Err(e) => {
-                    error!("ephemeral_file write_blob failed to get immutable buf to pre-warm page cache: {e:?}");
-                    // fail gracefully, it's not the end of the world if we can't pre-warm the cache here
-                }
-                Ok(v) => match v {
-                    page_cache::ReadBufResult::Found(_guard) => {
-                        // This function takes &mut self, so, it shouldn't be possible to reach this point.
-                        unreachable!("we just wrote block {blknum} to the VirtualFile, which is owned by Self, \
+
+        if matches!(self.prewarm_on_write, PrewarmOnWrite::Yes) {
+            // Pre-warm page cache with the contents.
+            // At least in isolated bulk ingest benchmarks (test_bulk_insert.py), the pre-warming
+            // benefits the code that writes InMemoryLayer=>L0 layers.
+
+            let cache = page_cache::get();
+            static CTX: Lazy<RequestContext> = Lazy::new(|| {
+                RequestContext::new(
+                    crate::task_mgr::TaskKind::EphemeralFilePreWarmPageCache,
+                    crate::context::DownloadBehavior::Error,
+                )
+            });
+            for blknum_in_buffer in 0..nblocks {
+                let blk_in_buffer =
+                    &buf[blknum_in_buffer * PAGE_SZ..(blknum_in_buffer + 1) * PAGE_SZ];
+                let blknum = self
+                    .nwritten_blocks
+                    .checked_add(blknum_in_buffer as u32)
+                    .unwrap();
+                match cache
+                    .read_immutable_buf(self.page_cache_file_id, blknum, &CTX)
+                    .await
+                {
+                    Err(e) => {
+                        error!("ephemeral_file write_blob failed to get immutable buf to pre-warm page cache: {e:?}");
+                        // fail gracefully, it's not the end of the world if we can't pre-warm the cache here
+                    }
+                    Ok(v) => match v {
+                        page_cache::ReadBufResult::Found(_guard) => {
+                            // This function takes &mut self, so, it shouldn't be possible to reach this point.
+                            unreachable!("we just wrote block {blknum} to the VirtualFile, which is owned by Self, \
                                      and this function takes &mut self, so, no concurrent read_blk is possible");
-                    }
-                    page_cache::ReadBufResult::NotFound(mut write_guard) => {
-                        write_guard.copy_from_slice(blk_in_buffer);
-                        let _ = write_guard.mark_valid();
-                    }
-                },
+                        }
+                        page_cache::ReadBufResult::NotFound(mut write_guard) => {
+                            write_guard.copy_from_slice(blk_in_buffer);
+                            let _ = write_guard.mark_valid();
+                        }
+                    },
+                }
            }
        }
+
        self.nwritten_blocks = self.nwritten_blocks.checked_add(nblocks32).unwrap();
        Ok((buflen, buf.into_inner()))
    }
--- a/pageserver/src/tenant/ephemeral_file/zero_padded_read_write.rs
+++ b/pageserver/src/tenant/ephemeral_file/zero_padded_read_write.rs
@@ -75,6 +75,21 @@ where
        flushed_offset + u64::try_from(buffer.pending()).unwrap()
    }

+    /// Get a slice of all blocks that [`Self::read_blk`] would return as [`ReadResult::ServedFromZeroPaddedMutableTail`].
+    pub fn get_tail_zero_padded(&self) -> &[u8] {
+        let buffer: &zero_padded::Buffer<TAIL_SZ> = self.buffered_writer.inspect_buffer();
+        let buffer_written_up_to = buffer.pending();
+        // pad to next page boundary
+        let read_up_to = if buffer_written_up_to % PAGE_SZ == 0 {
+            buffer_written_up_to
+        } else {
+            buffer_written_up_to
+                .checked_add(PAGE_SZ - (buffer_written_up_to % PAGE_SZ))
+                .unwrap()
+        };
+        &buffer.as_zero_padded_slice()[0..read_up_to]
+    }
+
    pub(crate) async fn read_blk(&self, blknum: u32) -> Result<ReadResult<'_, W>, std::io::Error> {
        let flushed_offset = self.buffered_writer.as_inner().bytes_written();
        let buffer: &zero_padded::Buffer<TAIL_SZ> = self.buffered_writer.inspect_buffer();
--- a/pageserver/src/tenant/mgr.rs
+++ b/pageserver/src/tenant/mgr.rs
@@ -43,7 +43,8 @@ use crate::tenant::config::{
 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, GcError, SpawnMode, Tenant, TenantState};
+use crate::tenant::{AttachedTenantConf, GcError, LoadConfigError, SpawnMode, Tenant, TenantState};
+use crate::virtual_file::MaybeFatalIo;
 use crate::{InitializationOrder, TEMP_FILE_SUFFIX};

 use utils::crashsafe::path_with_suffix_extension;
@@ -51,7 +52,6 @@ use utils::fs_ext::PathExt;
 use utils::generation::Generation;
 use utils::id::{TenantId, TimelineId};

-use super::delete::DeleteTenantError;
 use super::remote_timeline_client::remote_tenant_path;
 use super::secondary::SecondaryTenant;
 use super::timeline::detach_ancestor::PreparedTimelineDetach;
@@ -109,12 +109,6 @@ pub(crate) enum TenantsMap {
    ShuttingDown(BTreeMap<TenantShardId, TenantSlot>),
 }

-pub(crate) enum TenantsMapRemoveResult {
-    Occupied(TenantSlot),
-    Vacant,
-    InProgress(utils::completion::Barrier),
-}
-
 /// 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)]
@@ -191,26 +185,6 @@ impl TenantsMap {
        }
    }

-    /// 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
-    /// slot if the enclosed tenant is shutdown.
-    pub(crate) fn remove(&mut self, tenant_shard_id: TenantShardId) -> TenantsMapRemoveResult {
-        use std::collections::btree_map::Entry;
-        match self {
-            TenantsMap::Initializing => TenantsMapRemoveResult::Vacant,
-            TenantsMap::Open(m) | TenantsMap::ShuttingDown(m) => match m.entry(tenant_shard_id) {
-                Entry::Occupied(entry) => match entry.get() {
-                    TenantSlot::InProgress(barrier) => {
-                        TenantsMapRemoveResult::InProgress(barrier.clone())
-                    }
-                    _ => TenantsMapRemoveResult::Occupied(entry.remove()),
-                },
-                Entry::Vacant(_entry) => TenantsMapRemoveResult::Vacant,
-            },
-        }
-    }
-
    #[cfg(all(debug_assertions, not(test)))]
    pub(crate) fn len(&self) -> usize {
        match self {
@@ -299,7 +273,7 @@ pub struct TenantManager {
 }

 fn emergency_generations(
-    tenant_confs: &HashMap<TenantShardId, anyhow::Result<LocationConf>>,
+    tenant_confs: &HashMap<TenantShardId, Result<LocationConf, LoadConfigError>>,
 ) -> HashMap<TenantShardId, TenantStartupMode> {
    tenant_confs
        .iter()
@@ -323,7 +297,7 @@ fn emergency_generations(

 async fn init_load_generations(
    conf: &'static PageServerConf,
-    tenant_confs: &HashMap<TenantShardId, anyhow::Result<LocationConf>>,
+    tenant_confs: &HashMap<TenantShardId, Result<LocationConf, LoadConfigError>>,
    resources: &TenantSharedResources,
    cancel: &CancellationToken,
 ) -> anyhow::Result<Option<HashMap<TenantShardId, TenantStartupMode>>> {
@@ -373,56 +347,32 @@ async fn init_load_generations(
 /// Given a directory discovered in the pageserver's tenants/ directory, attempt
 /// to load a tenant config from it.
 ///
-/// If file is missing, return Ok(None)
+/// If we cleaned up something expected (like an empty dir or a temp dir), return None.
 fn load_tenant_config(
    conf: &'static PageServerConf,
+    tenant_shard_id: TenantShardId,
    dentry: Utf8DirEntry,
-) -> anyhow::Result<Option<(TenantShardId, anyhow::Result<LocationConf>)>> {
+) -> Option<Result<LocationConf, LoadConfigError>> {
    let tenant_dir_path = dentry.path().to_path_buf();
    if crate::is_temporary(&tenant_dir_path) {
        info!("Found temporary tenant directory, removing: {tenant_dir_path}");
        // No need to use safe_remove_tenant_dir_all because this is already
        // a temporary path
-        if let Err(e) = std::fs::remove_dir_all(&tenant_dir_path) {
-            error!(
-                "Failed to remove temporary directory '{}': {:?}",
-                tenant_dir_path, e
-            );
-        }
-        return Ok(None);
+        std::fs::remove_dir_all(&tenant_dir_path).fatal_err("delete temporary tenant dir");
+        return None;
    }

    // This case happens if we crash during attachment before writing a config into the dir
    let is_empty = tenant_dir_path
        .is_empty_dir()
-        .with_context(|| format!("Failed to check whether {tenant_dir_path:?} is an empty dir"))?;
+        .fatal_err("Checking for empty tenant dir");
    if is_empty {
        info!("removing empty tenant directory {tenant_dir_path:?}");
-        if let Err(e) = std::fs::remove_dir(&tenant_dir_path) {
-            error!(
-                "Failed to remove empty tenant directory '{}': {e:#}",
-                tenant_dir_path
-            )
-        }
-        return Ok(None);
+        std::fs::remove_dir(&tenant_dir_path).fatal_err("delete empty tenant dir");
+        return None;
    }

-    let tenant_shard_id = match tenant_dir_path
-        .file_name()
-        .unwrap_or_default()
-        .parse::<TenantShardId>()
-    {
-        Ok(id) => id,
-        Err(_) => {
-            warn!("Invalid tenant path (garbage in our repo directory?): {tenant_dir_path}",);
-            return Ok(None);
-        }
-    };
-
-    Ok(Some((
-        tenant_shard_id,
-        Tenant::load_tenant_config(conf, &tenant_shard_id),
-    )))
+    Some(Tenant::load_tenant_config(conf, &tenant_shard_id))
 }

 /// Initial stage of load: walk the local tenants directory, clean up any temp files,
@@ -432,32 +382,63 @@ fn load_tenant_config(
 /// seconds even on reasonably fast drives.
 async fn init_load_tenant_configs(
    conf: &'static PageServerConf,
-) -> anyhow::Result<HashMap<TenantShardId, anyhow::Result<LocationConf>>> {
+) -> HashMap<TenantShardId, Result<LocationConf, LoadConfigError>> {
    let tenants_dir = conf.tenants_path();

-    let dentries = tokio::task::spawn_blocking(move || -> anyhow::Result<Vec<Utf8DirEntry>> {
-        let dir_entries = tenants_dir
-            .read_dir_utf8()
-            .with_context(|| format!("Failed to list tenants dir {tenants_dir:?}"))?;
+    let dentries = tokio::task::spawn_blocking(move || -> Vec<Utf8DirEntry> {
+        let context = format!("read tenants dir {tenants_dir}");
+        let dir_entries = tenants_dir.read_dir_utf8().fatal_err(&context);

-        Ok(dir_entries.collect::<Result<Vec<_>, std::io::Error>>()?)
+        dir_entries
+            .collect::<Result<Vec<_>, std::io::Error>>()
+            .fatal_err(&context)
    })
-    .await??;
+    .await
+    .expect("Config load task panicked");

    let mut configs = HashMap::new();

    let mut join_set = JoinSet::new();
    for dentry in dentries {
-        join_set.spawn_blocking(move || load_tenant_config(conf, dentry));
+        let tenant_shard_id = match dentry.file_name().parse::<TenantShardId>() {
+            Ok(id) => id,
+            Err(_) => {
+                warn!(
+                    "Invalid tenant path (garbage in our repo directory?): '{}'",
+                    dentry.file_name()
+                );
+                continue;
+            }
+        };
+
+        join_set.spawn_blocking(move || {
+            (
+                tenant_shard_id,
+                load_tenant_config(conf, tenant_shard_id, dentry),
+            )
+        });
    }

    while let Some(r) = join_set.join_next().await {
-        if let Some((tenant_id, tenant_config)) = r?? {
-            configs.insert(tenant_id, tenant_config);
+        let (tenant_shard_id, tenant_config) = r.expect("Panic in config load task");
+        if let Some(tenant_config) = tenant_config {
+            configs.insert(tenant_shard_id, tenant_config);
        }
    }

-    Ok(configs)
+    configs
+}
+
+#[derive(Debug, thiserror::Error)]
+pub(crate) enum DeleteTenantError {
+    #[error("Tenant map slot error {0}")]
+    SlotError(#[from] TenantSlotError),
+
+    #[error("Cancelled")]
+    Cancelled,
+
+    #[error(transparent)]
+    Other(#[from] anyhow::Error),
 }

 /// Initialize repositories with locally available timelines.
@@ -487,7 +468,7 @@ pub async fn init_tenant_mgr(
    );

    // Scan local filesystem for attached tenants
-    let tenant_configs = init_load_tenant_configs(conf).await?;
+    let tenant_configs = init_load_tenant_configs(conf).await;

    // Determine which tenants are to be secondary or attached, and in which generation
    let tenant_modes = init_load_generations(conf, &tenant_configs, &resources, &cancel).await?;
@@ -510,17 +491,8 @@ pub async fn init_tenant_mgr(
        let mut location_conf = match location_conf {
            Ok(l) => l,
            Err(e) => {
-                warn!(tenant_id=%tenant_shard_id.tenant_id, shard_id=%tenant_shard_id.shard_slug(), "Marking tenant broken, failed to {e:#}");
-
-                tenants.insert(
-                    tenant_shard_id,
-                    TenantSlot::Attached(Tenant::create_broken_tenant(
-                        conf,
-                        tenant_shard_id,
-                        resources.remote_storage.clone(),
-                        format!("{}", e),
-                    )),
-                );
+                // This should only happen in the case of a serialization bug or critical local I/O error: we cannot load this tenant
+                error!(tenant_id=%tenant_shard_id.tenant_id, shard_id=%tenant_shard_id.shard_slug(), "Failed to load tenant config, failed to {e:#}");
                continue;
            }
        };
@@ -614,32 +586,23 @@ pub async fn init_tenant_mgr(
    );
    // For those shards that have live configurations, construct `Tenant` or `SecondaryTenant` objects and start them running
    for (tenant_shard_id, location_conf, config_write_result) in config_write_results {
-        // Errors writing configs are fatal
-        config_write_result?;
+        // Writing a config to local disk is foundational to startup up tenants: panic if we can't.
+        config_write_result.fatal_err("write tenant shard config file");

        let tenant_dir_path = conf.tenant_path(&tenant_shard_id);
        let shard_identity = location_conf.shard;
        let slot = match location_conf.mode {
-            LocationMode::Attached(attached_conf) => {
-                match tenant_spawn(
-                    conf,
-                    tenant_shard_id,
-                    &tenant_dir_path,
-                    resources.clone(),
-                    AttachedTenantConf::new(location_conf.tenant_conf, attached_conf),
-                    shard_identity,
-                    Some(init_order.clone()),
-                    &TENANTS,
-                    SpawnMode::Lazy,
-                    &ctx,
-                ) {
-                    Ok(tenant) => TenantSlot::Attached(tenant),
-                    Err(e) => {
-                        error!(tenant_id=%tenant_shard_id.tenant_id, shard_id=%tenant_shard_id.shard_slug(), "Failed to start tenant: {e:#}");
-                        continue;
-                    }
-                }
-            }
+            LocationMode::Attached(attached_conf) => TenantSlot::Attached(tenant_spawn(
+                conf,
+                tenant_shard_id,
+                &tenant_dir_path,
+                resources.clone(),
+                AttachedTenantConf::new(location_conf.tenant_conf, attached_conf),
+                shard_identity,
+                Some(init_order.clone()),
+                SpawnMode::Lazy,
+                &ctx,
+            )),
            LocationMode::Secondary(secondary_conf) => {
                info!(
                    tenant_id = %tenant_shard_id.tenant_id,
@@ -674,8 +637,7 @@ pub async fn init_tenant_mgr(
    })
 }

-/// Wrapper for Tenant::spawn that checks invariants before running, and inserts
-/// a broken tenant in the map if Tenant::spawn fails.
+/// Wrapper for Tenant::spawn that checks invariants before running
 #[allow(clippy::too_many_arguments)]
 fn tenant_spawn(
    conf: &'static PageServerConf,
@@ -685,45 +647,29 @@ fn tenant_spawn(
    location_conf: AttachedTenantConf,
    shard_identity: ShardIdentity,
    init_order: Option<InitializationOrder>,
-    tenants: &'static std::sync::RwLock<TenantsMap>,
    mode: SpawnMode,
    ctx: &RequestContext,
-) -> anyhow::Result<Arc<Tenant>> {
-    anyhow::ensure!(
-        tenant_path.is_dir(),
-        "Cannot load tenant from path {tenant_path:?}, it either does not exist or not a directory"
-    );
-    anyhow::ensure!(
-        !crate::is_temporary(tenant_path),
-        "Cannot load tenant from temporary path {tenant_path:?}"
-    );
-    anyhow::ensure!(
-        !tenant_path.is_empty_dir().with_context(|| {
-            format!("Failed to check whether {tenant_path:?} is an empty dir")
-        })?,
-        "Cannot load tenant from empty directory {tenant_path:?}"
-    );
+) -> Arc<Tenant> {
+    // All these conditions should have been satisfied by our caller: the tenant dir exists, is a well formed
+    // path, and contains a configuration file.  Assertions that do synchronous I/O are limited to debug mode
+    // to avoid impacting prod runtime performance.
+    assert!(!crate::is_temporary(tenant_path));
+    debug_assert!(tenant_path.is_dir());
+    debug_assert!(conf
+        .tenant_location_config_path(&tenant_shard_id)
+        .try_exists()
+        .unwrap());

-    let remote_storage = resources.remote_storage.clone();
-    let tenant = match Tenant::spawn(
+    Tenant::spawn(
        conf,
        tenant_shard_id,
        resources,
        location_conf,
        shard_identity,
        init_order,
-        tenants,
        mode,
        ctx,
-    ) {
-        Ok(tenant) => tenant,
-        Err(e) => {
-            error!("Failed to spawn tenant {tenant_shard_id}, reason: {e:#}");
-            Tenant::create_broken_tenant(conf, tenant_shard_id, remote_storage, format!("{e:#}"))
-        }
-    };
-
-    Ok(tenant)
+    )
 }

 async fn shutdown_all_tenants0(tenants: &std::sync::RwLock<TenantsMap>) {
@@ -874,8 +820,9 @@ pub(crate) enum UpsertLocationError {
    #[error("Failed to flush: {0}")]
    Flush(anyhow::Error),

+    /// This error variant is for unexpected situations (soft assertions) where the system is in an unexpected state.
    #[error("Internal error: {0}")]
-    Other(#[from] anyhow::Error),
+    InternalError(anyhow::Error),
 }

 impl TenantManager {
@@ -1005,7 +952,8 @@ impl TenantManager {
        match fast_path_taken {
            Some(FastPathModified::Attached(tenant)) => {
                Tenant::persist_tenant_config(self.conf, &tenant_shard_id, &new_location_config)
-                    .await?;
+                    .await
+                    .fatal_err("write tenant shard config");

                // Transition to AttachedStale means we may well hold a valid generation
                // still, and have been requested to go stale as part of a migration.  If
@@ -1035,7 +983,8 @@ impl TenantManager {
            }
            Some(FastPathModified::Secondary(_secondary_tenant)) => {
                Tenant::persist_tenant_config(self.conf, &tenant_shard_id, &new_location_config)
-                    .await?;
+                    .await
+                    .fatal_err("write tenant shard config");

                return Ok(None);
            }
@@ -1101,7 +1050,7 @@ impl TenantManager {
            Some(TenantSlot::InProgress(_)) => {
                // This should never happen: acquire_slot should error out
                // if the contents of a slot were InProgress.
-                return Err(UpsertLocationError::Other(anyhow::anyhow!(
+                return Err(UpsertLocationError::InternalError(anyhow::anyhow!(
                    "Acquired an InProgress slot, this is a bug."
                )));
            }
@@ -1120,12 +1069,14 @@ impl TenantManager {
        // Does not need to be fsync'd because local storage is just a cache.
        tokio::fs::create_dir_all(&timelines_path)
            .await
-            .with_context(|| format!("Creating {timelines_path}"))?;
+            .fatal_err("create timelines/ dir");

        // Before activating either secondary or attached mode, persist the
        // configuration, so that on restart we will re-attach (or re-start
        // secondary) on the tenant.
-        Tenant::persist_tenant_config(self.conf, &tenant_shard_id, &new_location_config).await?;
+        Tenant::persist_tenant_config(self.conf, &tenant_shard_id, &new_location_config)
+            .await
+            .fatal_err("write tenant shard config");

        let new_slot = match &new_location_config.mode {
            LocationMode::Secondary(secondary_config) => {
@@ -1144,13 +1095,15 @@ impl TenantManager {
                // from upserts.  This enables creating generation-less tenants even though neon_local
                // always uses generations when calling the location conf API.
                let attached_conf = if cfg!(feature = "testing") {
-                    let mut conf = AttachedTenantConf::try_from(new_location_config)?;
+                    let mut conf = AttachedTenantConf::try_from(new_location_config)
+                        .map_err(UpsertLocationError::BadRequest)?;
                    if self.conf.control_plane_api.is_none() {
                        conf.location.generation = Generation::none();
                    }
                    conf
                } else {
-                    AttachedTenantConf::try_from(new_location_config)?
+                    AttachedTenantConf::try_from(new_location_config)
+                        .map_err(UpsertLocationError::BadRequest)?
                };

                let tenant = tenant_spawn(
@@ -1161,10 +1114,9 @@ impl TenantManager {
                    attached_conf,
                    shard_identity,
                    None,
-                    self.tenants,
                    spawn_mode,
                    ctx,
-                )?;
+                );

                TenantSlot::Attached(tenant)
            }
@@ -1178,7 +1130,7 @@ impl TenantManager {

        match slot_guard.upsert(new_slot) {
            Err(TenantSlotUpsertError::InternalError(e)) => {
-                Err(UpsertLocationError::Other(anyhow::anyhow!(e)))
+                Err(UpsertLocationError::InternalError(anyhow::anyhow!(e)))
            }
            Err(TenantSlotUpsertError::MapState(e)) => Err(UpsertLocationError::Unavailable(e)),
            Err(TenantSlotUpsertError::ShuttingDown((new_slot, _completion))) => {
@@ -1283,10 +1235,9 @@ impl TenantManager {
            AttachedTenantConf::try_from(config)?,
            shard_identity,
            None,
-            self.tenants,
            SpawnMode::Eager,
            ctx,
-        )?;
+        );

        slot_guard.upsert(TenantSlot::Attached(tenant))?;

@@ -1634,7 +1585,7 @@ impl TenantManager {
        for child_shard_id in &child_shards {
            let child_shard_id = *child_shard_id;
            let child_shard = {
-                let locked = TENANTS.read().unwrap();
+                let locked = self.tenants.read().unwrap();
                let peek_slot =
                    tenant_map_peek_slot(&locked, &child_shard_id, TenantSlotPeekMode::Read)?;
                peek_slot.and_then(|s| s.get_attached()).cloned()
@@ -1735,6 +1686,7 @@ impl TenantManager {
            let timelines = parent_shard.timelines.lock().unwrap().clone();
            let parent_timelines = timelines.keys().cloned().collect::<Vec<_>>();
            for timeline in timelines.values() {
+                tracing::info!(timeline_id=%timeline.timeline_id, "Loading list of layers to hardlink");
                let timeline_layers = timeline
                    .layers
                    .read()
@@ -1774,7 +1726,12 @@ impl TenantManager {

        // Since we will do a large number of small filesystem metadata operations, batch them into
        // spawn_blocking calls rather than doing each one as a tokio::fs round-trip.
+        let span = tracing::Span::current();
        let jh = tokio::task::spawn_blocking(move || -> anyhow::Result<usize> {
+            // Run this synchronous code in the same log context as the outer function that spawned it.
+            let _span = span.enter();
+
+            tracing::info!("Creating {} directories", create_dirs.len());
            for dir in &create_dirs {
                if let Err(e) = std::fs::create_dir_all(dir) {
                    // Ignore AlreadyExists errors, drop out on all other errors
@@ -1788,6 +1745,11 @@ impl TenantManager {
            }

            for child_prefix in child_prefixes {
+                tracing::info!(
+                    "Hard-linking {} parent layers into child path {}",
+                    parent_layers.len(),
+                    child_prefix
+                );
                for relative_layer in &parent_layers {
                    let parent_path = parent_path.join(relative_layer);
                    let child_path = child_prefix.join(relative_layer);
@@ -1813,6 +1775,7 @@ impl TenantManager {
            // Durability is not required for correctness, but if we crashed during split and
            // then came restarted with empty timeline dirs, it would be very inefficient to
            // re-populate from remote storage.
+            tracing::info!("fsyncing {} directories", create_dirs.len());
            for dir in create_dirs {
                if let Err(e) = crashsafe::fsync(&dir) {
                    // Something removed a newly created timeline dir out from underneath us?  Extremely
@@ -1866,7 +1829,7 @@ impl TenantManager {
        deletion_queue_client: &DeletionQueueClient,
    ) -> Result<(), TenantStateError> {
        let tmp_path = self
-            .detach_tenant0(conf, &TENANTS, tenant_shard_id, deletion_queue_client)
+            .detach_tenant0(conf, tenant_shard_id, deletion_queue_client)
            .await?;
        spawn_background_purge(tmp_path);

@@ -1876,7 +1839,6 @@ impl TenantManager {
    async fn detach_tenant0(
        &self,
        conf: &'static PageServerConf,
-        tenants: &std::sync::RwLock<TenantsMap>,
        tenant_shard_id: TenantShardId,
        deletion_queue_client: &DeletionQueueClient,
    ) -> Result<Utf8PathBuf, TenantStateError> {
@@ -1890,7 +1852,7 @@ impl TenantManager {
        };

        let removal_result = remove_tenant_from_memory(
-            tenants,
+            self.tenants,
            tenant_shard_id,
            tenant_dir_rename_operation(tenant_shard_id),
        )
@@ -1906,7 +1868,7 @@ impl TenantManager {
    pub(crate) fn list_tenants(
        &self,
    ) -> Result<Vec<(TenantShardId, TenantState, Generation)>, TenantMapListError> {
-        let tenants = TENANTS.read().unwrap();
+        let tenants = self.tenants.read().unwrap();
        let m = match &*tenants {
            TenantsMap::Initializing => return Err(TenantMapListError::Initializing),
            TenantsMap::Open(m) | TenantsMap::ShuttingDown(m) => m,
@@ -2007,10 +1969,9 @@ impl TenantManager {
            AttachedTenantConf::try_from(config)?,
            shard_identity,
            None,
-            self.tenants,
            SpawnMode::Eager,
            ctx,
-        )?;
+        );

        slot_guard.upsert(TenantSlot::Attached(tenant))?;

--- a/pageserver/src/tenant/remote_timeline_client.rs
+++ b/pageserver/src/tenant/remote_timeline_client.rs
@@ -519,7 +519,7 @@ impl RemoteTimelineClient {
        local_path: &Utf8Path,
        cancel: &CancellationToken,
        ctx: &RequestContext,
-    ) -> anyhow::Result<u64> {
+    ) -> Result<u64, DownloadError> {
        let downloaded_size = {
            let _unfinished_gauge_guard = self.metrics.call_begin(
                &RemoteOpFileKind::Layer,
--- a/pageserver/src/tenant/secondary.rs
+++ b/pageserver/src/tenant/secondary.rs
@@ -23,6 +23,8 @@ use super::{
    storage_layer::LayerName,
 };

+use crate::metrics::SECONDARY_RESIDENT_PHYSICAL_SIZE;
+use metrics::UIntGauge;
 use pageserver_api::{
    models,
    shard::{ShardIdentity, TenantShardId},
@@ -99,6 +101,17 @@ pub(crate) struct SecondaryTenant {

    // Public state indicating overall progress of downloads relative to the last heatmap seen
    pub(crate) progress: std::sync::Mutex<models::SecondaryProgress>,
+
+    // Sum of layer sizes on local disk
+    pub(super) resident_size_metric: UIntGauge,
+}
+
+impl Drop for SecondaryTenant {
+    fn drop(&mut self) {
+        let tenant_id = self.tenant_shard_id.tenant_id.to_string();
+        let shard_id = format!("{}", self.tenant_shard_id.shard_slug());
+        let _ = SECONDARY_RESIDENT_PHYSICAL_SIZE.remove_label_values(&[&tenant_id, &shard_id]);
+    }
 }

 impl SecondaryTenant {
@@ -108,6 +121,12 @@ impl SecondaryTenant {
        tenant_conf: TenantConfOpt,
        config: &SecondaryLocationConfig,
    ) -> Arc<Self> {
+        let tenant_id = tenant_shard_id.tenant_id.to_string();
+        let shard_id = format!("{}", tenant_shard_id.shard_slug());
+        let resident_size_metric = SECONDARY_RESIDENT_PHYSICAL_SIZE
+            .get_metric_with_label_values(&[&tenant_id, &shard_id])
+            .unwrap();
+
        Arc::new(Self {
            tenant_shard_id,
            // todo: shall we make this a descendent of the
@@ -123,6 +142,8 @@ impl SecondaryTenant {
            detail: std::sync::Mutex::new(SecondaryDetail::new(config.clone())),

            progress: std::sync::Mutex::default(),
+
+            resident_size_metric,
        })
    }

@@ -211,16 +232,12 @@ impl SecondaryTenant {
            // have to 100% match what is on disk, because it's a best-effort warming
            // of the cache.
            let mut detail = this.detail.lock().unwrap();
-            if let Some(timeline_detail) = detail.timelines.get_mut(&timeline_id) {
-                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);
-                }
+            if let Some(removed) =
+                detail.evict_layer(name, &timeline_id, now, &this.resident_size_metric)
+            {
+                // We might race with removal of the same layer during downloads, so finding the layer we
+                // were trying to remove is optional.  Only issue the disk I/O to remove it if we found it.
+                removed.remove_blocking();
            }
        })
        .await
--- a/pageserver/src/tenant/secondary/downloader.rs
+++ b/pageserver/src/tenant/secondary/downloader.rs
@@ -46,6 +46,7 @@ use crate::tenant::{
 use camino::Utf8PathBuf;
 use chrono::format::{DelayedFormat, StrftimeItems};
 use futures::Future;
+use metrics::UIntGauge;
 use pageserver_api::models::SecondaryProgress;
 use pageserver_api::shard::TenantShardId;
 use remote_storage::{DownloadError, Etag, GenericRemoteStorage};
@@ -131,16 +132,66 @@ impl OnDiskState {
            .or_else(fs_ext::ignore_not_found)
            .fatal_err("Deleting secondary layer")
    }
+
+    pub(crate) fn file_size(&self) -> u64 {
+        self.metadata.file_size
+    }
 }

 #[derive(Debug, Clone, Default)]
 pub(super) struct SecondaryDetailTimeline {
-    pub(super) on_disk_layers: HashMap<LayerName, OnDiskState>,
+    on_disk_layers: HashMap<LayerName, OnDiskState>,

    /// We remember when layers were evicted, to prevent re-downloading them.
    pub(super) evicted_at: HashMap<LayerName, SystemTime>,
 }

+impl SecondaryDetailTimeline {
+    pub(super) fn remove_layer(
+        &mut self,
+        name: &LayerName,
+        resident_metric: &UIntGauge,
+    ) -> Option<OnDiskState> {
+        let removed = self.on_disk_layers.remove(name);
+        if let Some(removed) = &removed {
+            resident_metric.sub(removed.file_size());
+        }
+        removed
+    }
+
+    /// `local_path`
+    fn touch_layer<F>(
+        &mut self,
+        conf: &'static PageServerConf,
+        tenant_shard_id: &TenantShardId,
+        timeline_id: &TimelineId,
+        touched: &HeatMapLayer,
+        resident_metric: &UIntGauge,
+        local_path: F,
+    ) where
+        F: FnOnce() -> Utf8PathBuf,
+    {
+        use std::collections::hash_map::Entry;
+        match self.on_disk_layers.entry(touched.name.clone()) {
+            Entry::Occupied(mut v) => {
+                v.get_mut().access_time = touched.access_time;
+            }
+            Entry::Vacant(e) => {
+                e.insert(OnDiskState::new(
+                    conf,
+                    tenant_shard_id,
+                    timeline_id,
+                    touched.name.clone(),
+                    touched.metadata.clone(),
+                    touched.access_time,
+                    local_path(),
+                ));
+                resident_metric.add(touched.metadata.file_size);
+            }
+        }
+    }
+}
+
 // Aspects of a heatmap that we remember after downloading it
 #[derive(Clone, Debug)]
 struct DownloadSummary {
@@ -158,7 +209,7 @@ pub(super) struct SecondaryDetail {

    last_download: Option<DownloadSummary>,
    next_download: Option<Instant>,
-    pub(super) timelines: HashMap<TimelineId, SecondaryDetailTimeline>,
+    timelines: HashMap<TimelineId, SecondaryDetailTimeline>,
 }

 /// Helper for logging SystemTime
@@ -191,6 +242,38 @@ impl SecondaryDetail {
        }
    }

+    pub(super) fn evict_layer(
+        &mut self,
+        name: LayerName,
+        timeline_id: &TimelineId,
+        now: SystemTime,
+        resident_metric: &UIntGauge,
+    ) -> Option<OnDiskState> {
+        let timeline = self.timelines.get_mut(timeline_id)?;
+        let removed = timeline.remove_layer(&name, resident_metric);
+        if removed.is_some() {
+            timeline.evicted_at.insert(name, now);
+        }
+        removed
+    }
+
+    pub(super) fn remove_timeline(
+        &mut self,
+        timeline_id: &TimelineId,
+        resident_metric: &UIntGauge,
+    ) {
+        let removed = self.timelines.remove(timeline_id);
+        if let Some(removed) = removed {
+            resident_metric.sub(
+                removed
+                    .on_disk_layers
+                    .values()
+                    .map(|l| l.metadata.file_size)
+                    .sum(),
+            );
+        }
+    }
+
    /// Additionally returns the total number of layers, used for more stable relative access time
    /// based eviction.
    pub(super) fn get_layers_for_eviction(
@@ -262,6 +345,7 @@ impl scheduler::RunningJob for RunningDownload {
 struct CompleteDownload {
    secondary_state: Arc<SecondaryTenant>,
    completed_at: Instant,
+    result: Result<(), UpdateError>,
 }

 impl scheduler::Completion for CompleteDownload {
@@ -286,21 +370,33 @@ impl JobGenerator<PendingDownload, RunningDownload, CompleteDownload, DownloadCo
        let CompleteDownload {
            secondary_state,
            completed_at: _completed_at,
+            result,
        } = completion;

        tracing::debug!("Secondary tenant download completed");

        let mut detail = secondary_state.detail.lock().unwrap();

-        let period = detail
-            .last_download
-            .as_ref()
-            .map(|d| d.upload_period)
-            .unwrap_or(DEFAULT_DOWNLOAD_INTERVAL);
+        match result {
+            Err(UpdateError::Restart) => {
+                // Start downloading again as soon as we can.  This will involve waiting for the scheduler's
+                // scheduling interval.  This slightly reduces the peak download speed of tenants that hit their
+                // deadline and keep restarting, but that also helps give other tenants a chance to execute rather
+                // that letting one big tenant dominate for a long time.
+                detail.next_download = Some(Instant::now());
+            }
+            _ => {
+                let period = detail
+                    .last_download
+                    .as_ref()
+                    .map(|d| d.upload_period)
+                    .unwrap_or(DEFAULT_DOWNLOAD_INTERVAL);

-        // We advance next_download irrespective of errors: we don't want error cases to result in
-        // expensive busy-polling.
-        detail.next_download = Some(Instant::now() + period_jitter(period, 5));
+                // We advance next_download irrespective of errors: we don't want error cases to result in
+                // expensive busy-polling.
+                detail.next_download = Some(Instant::now() + period_jitter(period, 5));
+            }
+        }
    }

    async fn schedule(&mut self) -> SchedulingResult<PendingDownload> {
@@ -396,9 +492,10 @@ impl JobGenerator<PendingDownload, RunningDownload, CompleteDownload, DownloadCo
        (RunningDownload { barrier }, Box::pin(async move {
            let _completion = completion;

-            match TenantDownloader::new(conf, &remote_storage, &secondary_state)
+            let result = TenantDownloader::new(conf, &remote_storage, &secondary_state)
                .download(&download_ctx)
-                .await
+                .await;
+            match &result
            {
                Err(UpdateError::NoData) => {
                    tracing::info!("No heatmap found for tenant.  This is fine if it is new.");
@@ -415,6 +512,9 @@ impl JobGenerator<PendingDownload, RunningDownload, CompleteDownload, DownloadCo
                Err(e @ (UpdateError::DownloadError(_) | UpdateError::Other(_))) => {
                    tracing::error!("Error while downloading tenant: {e}");
                },
+                Err(UpdateError::Restart) => {
+                    tracing::info!("Download reached deadline & will restart to update heatmap")
+                }
                Ok(()) => {}
            };

@@ -436,6 +536,7 @@ impl JobGenerator<PendingDownload, RunningDownload, CompleteDownload, DownloadCo
            CompleteDownload {
                secondary_state,
                completed_at: Instant::now(),
+                result
            }
        }.instrument(info_span!(parent: None, "secondary_download", tenant_id=%tenant_shard_id.tenant_id, shard_id=%tenant_shard_id.shard_slug()))))
    }
@@ -452,6 +553,11 @@ struct TenantDownloader<'a> {
 /// Errors that may be encountered while updating a tenant
 #[derive(thiserror::Error, Debug)]
 enum UpdateError {
+    /// This is not a true failure, but it's how a download indicates that it would like to be restarted by
+    /// the scheduler, to pick up the latest heatmap
+    #[error("Reached deadline, restarting downloads")]
+    Restart,
+
    #[error("No remote data found")]
    NoData,
    #[error("Insufficient local storage space")]
@@ -578,8 +684,13 @@ impl<'a> TenantDownloader<'a> {
                Some(t) => t,
                None => {
                    // We have no existing state: need to scan local disk for layers first.
-                    let timeline_state =
-                        init_timeline_state(self.conf, tenant_shard_id, timeline).await;
+                    let timeline_state = init_timeline_state(
+                        self.conf,
+                        tenant_shard_id,
+                        timeline,
+                        &self.secondary_state.resident_size_metric,
+                    )
+                    .await;

                    // Re-acquire detail lock now that we're done with async load from local FS
                    self.secondary_state
@@ -603,6 +714,26 @@ impl<'a> TenantDownloader<'a> {
                self.prepare_timelines(&heatmap, heatmap_mtime).await?;
        }

+        // Calculate a deadline for downloads: if downloading takes longer than this, it is useful to drop out and start again,
+        // so that we are always using reasonably a fresh heatmap.  Otherwise, if we had really huge content to download, we might
+        // spend 10s of minutes downloading layers we don't need.
+        // (see https://github.com/neondatabase/neon/issues/8182)
+        let deadline = {
+            let period = self
+                .secondary_state
+                .detail
+                .lock()
+                .unwrap()
+                .last_download
+                .as_ref()
+                .map(|d| d.upload_period)
+                .unwrap_or(DEFAULT_DOWNLOAD_INTERVAL);
+
+            // Use double the period: we are not promising to complete within the period, this is just a heuristic
+            // to keep using a "reasonably fresh" heatmap.
+            Instant::now() + period * 2
+        };
+
        // Download the layers in the heatmap
        for timeline in heatmap.timelines {
            let timeline_state = timeline_states
@@ -618,7 +749,7 @@ impl<'a> TenantDownloader<'a> {
            }

            let timeline_id = timeline.timeline_id;
-            self.download_timeline(timeline, timeline_state, ctx)
+            self.download_timeline(timeline, timeline_state, deadline, ctx)
                .instrument(tracing::info_span!(
                    "secondary_download_timeline",
                    tenant_id=%tenant_shard_id.tenant_id,
@@ -628,6 +759,25 @@ impl<'a> TenantDownloader<'a> {
                .await?;
        }

+        // Metrics consistency check in testing builds
+        if cfg!(feature = "testing") {
+            let detail = self.secondary_state.detail.lock().unwrap();
+            let resident_size = detail
+                .timelines
+                .values()
+                .map(|tl| {
+                    tl.on_disk_layers
+                        .values()
+                        .map(|v| v.metadata.file_size)
+                        .sum::<u64>()
+                })
+                .sum::<u64>();
+            assert_eq!(
+                resident_size,
+                self.secondary_state.resident_size_metric.get()
+            );
+        }
+
        // Only update last_etag after a full successful download: this way will not skip
        // the next download, even if the heatmap's actual etag is unchanged.
        self.secondary_state.detail.lock().unwrap().last_download = Some(DownloadSummary {
@@ -740,7 +890,7 @@ impl<'a> TenantDownloader<'a> {
            for delete_timeline in &delete_timelines {
                // We haven't removed from disk yet, but optimistically remove from in-memory state: if removal
                // from disk fails that will be a fatal error.
-                detail.timelines.remove(delete_timeline);
+                detail.remove_timeline(delete_timeline, &self.secondary_state.resident_size_metric);
            }
        }

@@ -758,7 +908,7 @@ impl<'a> TenantDownloader<'a> {
            let Some(timeline_state) = detail.timelines.get_mut(&timeline_id) else {
                continue;
            };
-            timeline_state.on_disk_layers.remove(&layer_name);
+            timeline_state.remove_layer(&layer_name, &self.secondary_state.resident_size_metric);
        }

        for timeline_id in delete_timelines {
@@ -827,26 +977,28 @@ impl<'a> TenantDownloader<'a> {
        .and_then(|x| x)
    }

-    async fn download_timeline(
+    /// Download heatmap layers that are not present on local disk, or update their
+    /// access time if they are already present.
+    async fn download_timeline_layers(
        &self,
+        tenant_shard_id: &TenantShardId,
        timeline: HeatMapTimeline,
        timeline_state: SecondaryDetailTimeline,
+        deadline: Instant,
        ctx: &RequestContext,
-    ) -> Result<(), UpdateError> {
-        debug_assert_current_span_has_tenant_and_timeline_id();
-        let tenant_shard_id = self.secondary_state.get_tenant_shard_id();
-
+    ) -> (Result<(), UpdateError>, Vec<HeatMapLayer>) {
        // Accumulate updates to the state
        let mut touched = Vec::new();

-        tracing::debug!(timeline_id=%timeline.timeline_id, "Downloading layers, {} in heatmap", timeline.layers.len());
-
-        // 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 {
            if self.secondary_state.cancel.is_cancelled() {
                tracing::debug!("Cancelled -- dropping out of layer loop");
-                return Err(UpdateError::Cancelled);
+                return (Err(UpdateError::Cancelled), touched);
+            }
+
+            if Instant::now() > deadline {
+                // We've been running downloads for a while, restart to download latest heatmap.
+                return (Err(UpdateError::Restart), touched);
            }

            // Existing on-disk layers: just update their access time.
@@ -916,52 +1068,66 @@ impl<'a> TenantDownloader<'a> {

            match self
                .download_layer(tenant_shard_id, &timeline.timeline_id, layer, ctx)
-                .await?
+                .await
            {
-                Some(layer) => touched.push(layer),
-                None => {
+                Ok(Some(layer)) => touched.push(layer),
+                Ok(None) => {
                    // Not an error but we didn't download it: remote layer is missing.  Don't add it to the list of
                    // things to consider touched.
                }
-            }
-        }
-
-        // Write updates to state to record layers we just downloaded or touched.
-        {
-            let mut detail = self.secondary_state.detail.lock().unwrap();
-            let timeline_detail = detail.timelines.entry(timeline.timeline_id).or_default();
-
-            tracing::info!("Wrote timeline_detail for {} touched layers", touched.len());
-
-            for t in touched {
-                use std::collections::hash_map::Entry;
-                match timeline_detail.on_disk_layers.entry(t.name.clone()) {
-                    Entry::Occupied(mut v) => {
-                        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,
-                            &timeline.timeline_id,
-                            t.name,
-                            t.metadata.clone(),
-                            t.access_time,
-                            local_path,
-                        ));
-                    }
+                Err(e) => {
+                    return (Err(e), touched);
                }
            }
        }

-        Ok(())
+        (Ok(()), touched)
+    }
+
+    async fn download_timeline(
+        &self,
+        timeline: HeatMapTimeline,
+        timeline_state: SecondaryDetailTimeline,
+        deadline: Instant,
+        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_id = timeline.timeline_id;
+
+        tracing::debug!(timeline_id=%timeline_id, "Downloading layers, {} in heatmap", timeline.layers.len());
+
+        let (result, touched) = self
+            .download_timeline_layers(tenant_shard_id, timeline, timeline_state, deadline, ctx)
+            .await;
+
+        // Write updates to state to record layers we just downloaded or touched, irrespective of whether the overall result was successful
+        {
+            let mut detail = self.secondary_state.detail.lock().unwrap();
+            let timeline_detail = detail.timelines.entry(timeline_id).or_default();
+
+            tracing::info!("Wrote timeline_detail for {} touched layers", touched.len());
+            touched.into_iter().for_each(|t| {
+                timeline_detail.touch_layer(
+                    self.conf,
+                    tenant_shard_id,
+                    &timeline_id,
+                    &t,
+                    &self.secondary_state.resident_size_metric,
+                    || {
+                        local_layer_path(
+                            self.conf,
+                            tenant_shard_id,
+                            &timeline_id,
+                            &t.name,
+                            &t.metadata.generation,
+                        )
+                    },
+                )
+            });
+        }
+
+        result
    }

    /// Call this during timeline download if a layer will _not_ be downloaded, to update progress statistics
@@ -1067,6 +1233,7 @@ async fn init_timeline_state(
    conf: &'static PageServerConf,
    tenant_shard_id: &TenantShardId,
    heatmap: &HeatMapTimeline,
+    resident_metric: &UIntGauge,
 ) -> SecondaryDetailTimeline {
    let timeline_path = conf.timeline_path(tenant_shard_id, &heatmap.timeline_id);
    let mut detail = SecondaryDetailTimeline::default();
@@ -1142,17 +1309,13 @@ async fn init_timeline_state(
                        } else {
                            // We expect the access time to be initialized immediately afterwards, when
                            // the latest heatmap is applied to the state.
-                            detail.on_disk_layers.insert(
-                                name.clone(),
-                                OnDiskState::new(
-                                    conf,
-                                    tenant_shard_id,
-                                    &heatmap.timeline_id,
-                                    name,
-                                    remote_meta.metadata.clone(),
-                                    remote_meta.access_time,
-                                    file_path,
-                                ),
+                            detail.touch_layer(
+                                conf,
+                                tenant_shard_id,
+                                &heatmap.timeline_id,
+                                remote_meta,
+                                resident_metric,
+                                || file_path,
                            );
                        }
                    }
--- a/pageserver/src/tenant/secondary/heatmap_uploader.rs
+++ b/pageserver/src/tenant/secondary/heatmap_uploader.rs
@@ -367,10 +367,9 @@ async fn upload_tenant_heatmap(
    debug_assert_current_span_has_tenant_id();

    let generation = tenant.get_generation();
+    debug_assert!(!generation.is_none());
    if generation.is_none() {
-        // We do not expect this: generations were implemented before heatmap uploads.  However,
-        // handle it so that we don't have to make the generation in the heatmap an Option<>
-        // (Generation::none is not serializable)
+        // We do not expect this: None generations should only appear in historic layer metadata, not in running Tenants
        tracing::warn!("Skipping heatmap upload for tenant with generation==None");
        return Ok(UploadHeatmapOutcome::Skipped);
    }
--- a/pageserver/src/tenant/size.rs
+++ b/pageserver/src/tenant/size.rs
@@ -3,6 +3,7 @@ use std::collections::hash_map::Entry;
 use std::collections::{HashMap, HashSet};
 use std::sync::Arc;

+use tenant_size_model::svg::SvgBranchKind;
 use tokio::sync::oneshot::error::RecvError;
 use tokio::sync::Semaphore;
 use tokio_util::sync::CancellationToken;
@@ -87,6 +88,9 @@ impl SegmentMeta {
            LsnKind::BranchPoint => true,
            LsnKind::GcCutOff => true,
            LsnKind::BranchEnd => false,
+            LsnKind::LeasePoint => true,
+            LsnKind::LeaseStart => false,
+            LsnKind::LeaseEnd => false,
        }
    }
 }
@@ -103,6 +107,21 @@ pub enum LsnKind {
    GcCutOff,
    /// Last record LSN
    BranchEnd,
+    /// A LSN lease is granted here.
+    LeasePoint,
+    /// A lease starts from here.
+    LeaseStart,
+    /// Last record LSN for the lease (should have the same LSN as the previous [`LsnKind::LeaseStart`]).
+    LeaseEnd,
+}
+
+impl From<LsnKind> for SvgBranchKind {
+    fn from(kind: LsnKind) -> Self {
+        match kind {
+            LsnKind::LeasePoint | LsnKind::LeaseStart | LsnKind::LeaseEnd => SvgBranchKind::Lease,
+            _ => SvgBranchKind::Timeline,
+        }
+    }
 }

 /// Collect all relevant LSNs to the inputs. These will only be helpful in the serialized form as
@@ -124,6 +143,9 @@ pub struct TimelineInputs {

    /// Cutoff point calculated from the user-supplied 'max_retention_period'
    retention_param_cutoff: Option<Lsn>,
+
+    /// Lease points on the timeline
+    lease_points: Vec<Lsn>,
 }

 /// Gathers the inputs for the tenant sizing model.
@@ -234,6 +256,13 @@ pub(super) async fn gather_inputs(
            None
        };

+        let lease_points = gc_info
+            .leases
+            .keys()
+            .filter(|&&lsn| lsn > ancestor_lsn)
+            .copied()
+            .collect::<Vec<_>>();
+
        // next_gc_cutoff in parent branch are not of interest (right now at least), nor do we
        // want to query any logical size before initdb_lsn.
        let branch_start_lsn = cmp::max(ancestor_lsn, timeline.initdb_lsn);
@@ -248,6 +277,8 @@ pub(super) async fn gather_inputs(
            .map(|lsn| (lsn, LsnKind::BranchPoint))
            .collect::<Vec<_>>();

+        lsns.extend(lease_points.iter().map(|&lsn| (lsn, LsnKind::LeasePoint)));
+
        drop(gc_info);

        // Add branch points we collected earlier, just in case there were any that were
@@ -296,6 +327,7 @@ pub(super) async fn gather_inputs(
            if kind == LsnKind::BranchPoint {
                branchpoint_segments.insert((timeline_id, lsn), segments.len());
            }
+
            segments.push(SegmentMeta {
                segment: Segment {
                    parent: Some(parent),
@@ -306,7 +338,45 @@ pub(super) async fn gather_inputs(
                timeline_id: timeline.timeline_id,
                kind,
            });
-            parent += 1;
+
+            parent = segments.len() - 1;
+
+            if kind == LsnKind::LeasePoint {
+                // Needs `LeaseStart` and `LeaseEnd` as well to model lease as a read-only branch that never writes data
+                // (i.e. it's lsn has not advanced from ancestor_lsn), and therefore the three segments have the same LSN
+                // value. Without the other two segments, the calculation code would not count the leased LSN as a point
+                // to be retained.
+                // Did not use `BranchStart` or `BranchEnd` so we can differentiate branches and leases during debug.
+                //
+                // Alt Design: rewrite the entire calculation code to be independent of timeline id. Both leases and
+                // branch points can be given a synthetic id so we can unite them.
+                let mut lease_parent = parent;
+
+                // Start of a lease.
+                segments.push(SegmentMeta {
+                    segment: Segment {
+                        parent: Some(lease_parent),
+                        lsn: lsn.0,
+                        size: None,                   // Filled in later, if necessary
+                        needed: lsn > next_gc_cutoff, // only needed if the point is within rentention.
+                    },
+                    timeline_id: timeline.timeline_id,
+                    kind: LsnKind::LeaseStart,
+                });
+                lease_parent += 1;
+
+                // End of the lease.
+                segments.push(SegmentMeta {
+                    segment: Segment {
+                        parent: Some(lease_parent),
+                        lsn: lsn.0,
+                        size: None,   // Filled in later, if necessary
+                        needed: true, // everything at the lease LSN must be readable => is needed
+                    },
+                    timeline_id: timeline.timeline_id,
+                    kind: LsnKind::LeaseEnd,
+                });
+            }
        }

        // Current end of the timeline
@@ -332,6 +402,7 @@ pub(super) async fn gather_inputs(
            pitr_cutoff,
            next_gc_cutoff,
            retention_param_cutoff,
+            lease_points,
        });
    }

@@ -674,7 +745,8 @@ fn verify_size_for_multiple_branches() {
      "horizon_cutoff": "0/2210CD0",
      "pitr_cutoff": "0/2210CD0",
      "next_gc_cutoff": "0/2210CD0",
-      "retention_param_cutoff": null
+      "retention_param_cutoff": null,
+      "lease_points": []
    },
    {
      "timeline_id": "454626700469f0a9914949b9d018e876",
@@ -684,7 +756,8 @@ fn verify_size_for_multiple_branches() {
      "horizon_cutoff": "0/1817770",
      "pitr_cutoff": "0/1817770",
      "next_gc_cutoff": "0/1817770",
-      "retention_param_cutoff": null
+      "retention_param_cutoff": null,
+      "lease_points": []
    },
    {
      "timeline_id": "cb5e3cbe60a4afc00d01880e1a37047f",
@@ -694,7 +767,8 @@ fn verify_size_for_multiple_branches() {
      "horizon_cutoff": "0/18B3D98",
      "pitr_cutoff": "0/18B3D98",
      "next_gc_cutoff": "0/18B3D98",
-      "retention_param_cutoff": null
+      "retention_param_cutoff": null,
+      "lease_points": []
    }
  ]
 }
@@ -749,7 +823,8 @@ fn verify_size_for_one_branch() {
      "horizon_cutoff": "47/240A5860",
      "pitr_cutoff": "47/240A5860",
      "next_gc_cutoff": "47/240A5860",
-      "retention_param_cutoff": "0/0"
+      "retention_param_cutoff": "0/0",
+      "lease_points": []
    }
  ]
 }"#;
--- a/pageserver/src/tenant/storage_layer/delta_layer.rs
+++ b/pageserver/src/tenant/storage_layer/delta_layer.rs
@@ -49,7 +49,7 @@ use camino::{Utf8Path, Utf8PathBuf};
 use futures::StreamExt;
 use itertools::Itertools;
 use pageserver_api::keyspace::KeySpace;
-use pageserver_api::models::LayerAccessKind;
+use pageserver_api::models::{ImageCompressionAlgorithm, LayerAccessKind};
 use pageserver_api::shard::TenantShardId;
 use rand::{distributions::Alphanumeric, Rng};
 use serde::{Deserialize, Serialize};
@@ -452,7 +452,12 @@ impl DeltaLayerWriterInner {
        ctx: &RequestContext,
    ) -> (Vec<u8>, anyhow::Result<()>) {
        assert!(self.lsn_range.start <= lsn);
-        let (val, res) = self.blob_writer.write_blob(val, ctx).await;
+        // We don't want to use compression in delta layer creation
+        let compression = ImageCompressionAlgorithm::DisabledNoDecompress;
+        let (val, res) = self
+            .blob_writer
+            .write_blob_maybe_compressed(val, ctx, compression)
+            .await;
        let off = match res {
            Ok(off) => off,
            Err(e) => return (val, Err(anyhow::anyhow!(e))),
@@ -928,7 +933,6 @@ impl DeltaLayerInner {
    }

    /// Load all key-values in the delta layer, should be replaced by an iterator-based interface in the future.
-    #[cfg(test)]
    pub(super) async fn load_key_values(
        &self,
        ctx: &RequestContext,
@@ -941,7 +945,7 @@ impl DeltaLayerInner {
        );
        let mut result = Vec::new();
        let mut stream =
-            Box::pin(self.stream_index_forwards(&index_reader, &[0; DELTA_KEY_SIZE], ctx));
+            Box::pin(self.stream_index_forwards(index_reader, &[0; DELTA_KEY_SIZE], ctx));
        let block_reader = FileBlockReader::new(&self.file, self.file_id);
        let cursor = block_reader.block_cursor();
        let mut buf = Vec::new();
@@ -976,7 +980,7 @@ impl DeltaLayerInner {
        ctx: &RequestContext,
    ) -> anyhow::Result<Vec<VectoredRead>>
    where
-        Reader: BlockReader,
+        Reader: BlockReader + Clone,
    {
        let ctx = RequestContextBuilder::extend(ctx)
            .page_content_kind(PageContentKind::DeltaLayerBtreeNode)
@@ -986,7 +990,7 @@ impl DeltaLayerInner {
            let mut range_end_handled = false;

            let start_key = DeltaKey::from_key_lsn(&range.start, lsn_range.start);
-            let index_stream = index_reader.get_stream_from(&start_key.0, &ctx);
+            let index_stream = index_reader.clone().into_stream(&start_key.0, &ctx);
            let mut index_stream = std::pin::pin!(index_stream);

            while let Some(index_entry) = index_stream.next().await {
@@ -1241,7 +1245,7 @@ impl DeltaLayerInner {
            block_reader,
        );

-        let stream = self.stream_index_forwards(&tree_reader, &[0u8; DELTA_KEY_SIZE], ctx);
+        let stream = self.stream_index_forwards(tree_reader, &[0u8; DELTA_KEY_SIZE], ctx);
        let stream = stream.map_ok(|(key, lsn, pos)| Item::Actual(key, lsn, pos));
        // put in a sentinel value for getting the end offset for last item, and not having to
        // repeat the whole read part
@@ -1300,7 +1304,7 @@ impl DeltaLayerInner {
                        offsets.start.pos(),
                        offsets.end.pos(),
                        meta,
-                        max_read_size,
+                        Some(max_read_size),
                    ))
                }
            } else {
@@ -1459,17 +1463,17 @@ impl DeltaLayerInner {

    fn stream_index_forwards<'a, R>(
        &'a self,
-        reader: &'a DiskBtreeReader<R, DELTA_KEY_SIZE>,
+        reader: DiskBtreeReader<R, DELTA_KEY_SIZE>,
        start: &'a [u8; DELTA_KEY_SIZE],
        ctx: &'a RequestContext,
    ) -> impl futures::stream::Stream<
        Item = Result<(Key, Lsn, BlobRef), crate::tenant::disk_btree::DiskBtreeError>,
    > + 'a
    where
-        R: BlockReader,
+        R: BlockReader + 'a,
    {
        use futures::stream::TryStreamExt;
-        let stream = reader.get_stream_from(start, ctx);
+        let stream = reader.into_stream(start, ctx);
        stream.map_ok(|(key, value)| {
            let key = DeltaKey::from_slice(&key);
            let (key, lsn) = (key.key(), key.lsn());
@@ -1493,6 +1497,24 @@ impl DeltaLayerInner {
        );
        offset
    }
+
+    #[cfg(test)]
+    pub(crate) fn iter<'a>(&'a self, ctx: &'a RequestContext) -> DeltaLayerIterator<'a> {
+        let block_reader = FileBlockReader::new(&self.file, self.file_id);
+        let tree_reader =
+            DiskBtreeReader::new(self.index_start_blk, self.index_root_blk, block_reader);
+        DeltaLayerIterator {
+            delta_layer: self,
+            ctx,
+            index_iter: tree_reader.iter(&[0; DELTA_KEY_SIZE], ctx),
+            key_values_batch: std::collections::VecDeque::new(),
+            is_end: false,
+            planner: crate::tenant::vectored_blob_io::StreamingVectoredReadPlanner::new(
+                1024 * 8192, // The default value. Unit tests might use a different value. 1024 * 8K = 8MB buffer.
+                1024,        // The default value. Unit tests might use a different value
+            ),
+        }
+    }
 }

 /// A set of data associated with a delta layer key and its value
@@ -1552,6 +1574,70 @@ impl<'a> pageserver_compaction::interface::CompactionDeltaEntry<'a, Key> for Del
    }
 }

+#[cfg(test)]
+pub struct DeltaLayerIterator<'a> {
+    delta_layer: &'a DeltaLayerInner,
+    ctx: &'a RequestContext,
+    planner: crate::tenant::vectored_blob_io::StreamingVectoredReadPlanner,
+    index_iter: crate::tenant::disk_btree::DiskBtreeIterator<'a>,
+    key_values_batch: std::collections::VecDeque<(Key, Lsn, Value)>,
+    is_end: bool,
+}
+
+#[cfg(test)]
+impl<'a> DeltaLayerIterator<'a> {
+    /// Retrieve a batch of key-value pairs into the iterator buffer.
+    async fn next_batch(&mut self) -> anyhow::Result<()> {
+        assert!(self.key_values_batch.is_empty());
+        assert!(!self.is_end);
+
+        let plan = loop {
+            if let Some(res) = self.index_iter.next().await {
+                let (raw_key, value) = res?;
+                let key = Key::from_slice(&raw_key[..KEY_SIZE]);
+                let lsn = DeltaKey::extract_lsn_from_buf(&raw_key);
+                let blob_ref = BlobRef(value);
+                let offset = blob_ref.pos();
+                if let Some(batch_plan) = self.planner.handle(key, lsn, offset, BlobFlag::None) {
+                    break batch_plan;
+                }
+            } else {
+                self.is_end = true;
+                let data_end_offset = self.delta_layer.index_start_offset();
+                break self.planner.handle_range_end(data_end_offset);
+            }
+        };
+        let vectored_blob_reader = VectoredBlobReader::new(&self.delta_layer.file);
+        let mut next_batch = std::collections::VecDeque::new();
+        let buf_size = plan.size();
+        let buf = BytesMut::with_capacity(buf_size);
+        let blobs_buf = vectored_blob_reader
+            .read_blobs(&plan, buf, self.ctx)
+            .await?;
+        let frozen_buf = blobs_buf.buf.freeze();
+        for meta in blobs_buf.blobs.iter() {
+            let value = Value::des(&frozen_buf[meta.start..meta.end])?;
+            next_batch.push_back((meta.meta.key, meta.meta.lsn, value));
+        }
+        self.key_values_batch = next_batch;
+        Ok(())
+    }
+
+    pub async fn next(&mut self) -> anyhow::Result<Option<(Key, Lsn, Value)>> {
+        if self.key_values_batch.is_empty() {
+            if self.is_end {
+                return Ok(None);
+            }
+            self.next_batch().await?;
+        }
+        Ok(Some(
+            self.key_values_batch
+                .pop_front()
+                .expect("should not be empty"),
+        ))
+    }
+}
+
 #[cfg(test)]
 mod test {
    use std::collections::BTreeMap;
@@ -1561,6 +1647,9 @@ mod test {
    use rand::RngCore;

    use super::*;
+    use crate::tenant::harness::TIMELINE_ID;
+    use crate::tenant::vectored_blob_io::StreamingVectoredReadPlanner;
+    use crate::tenant::Tenant;
    use crate::{
        context::DownloadBehavior,
        task_mgr::TaskKind,
@@ -1857,7 +1946,7 @@ mod test {
            .finish(entries_meta.key_range.end, &timeline, &ctx)
            .await?;

-        let inner = resident.as_delta(&ctx).await?;
+        let inner = resident.get_as_delta(&ctx).await?;

        let file_size = inner.file.metadata().await?.len();
        tracing::info!(
@@ -2044,11 +2133,11 @@ mod test {

            let copied_layer = writer.finish(Key::MAX, &branch, ctx).await.unwrap();

-            copied_layer.as_delta(ctx).await.unwrap();
+            copied_layer.get_as_delta(ctx).await.unwrap();

            assert_keys_and_values_eq(
-                new_layer.as_delta(ctx).await.unwrap(),
-                copied_layer.as_delta(ctx).await.unwrap(),
+                new_layer.get_as_delta(ctx).await.unwrap(),
+                copied_layer.get_as_delta(ctx).await.unwrap(),
                truncate_at,
                ctx,
            )
@@ -2073,7 +2162,7 @@ mod test {
            source.index_root_blk,
            &source_reader,
        );
-        let source_stream = source.stream_index_forwards(&source_tree, &start_key, ctx);
+        let source_stream = source.stream_index_forwards(source_tree, &start_key, ctx);
        let source_stream = source_stream.filter(|res| match res {
            Ok((_, lsn, _)) => ready(lsn < &truncated_at),
            _ => ready(true),
@@ -2086,7 +2175,7 @@ mod test {
            truncated.index_root_blk,
            &truncated_reader,
        );
-        let truncated_stream = truncated.stream_index_forwards(&truncated_tree, &start_key, ctx);
+        let truncated_stream = truncated.stream_index_forwards(truncated_tree, &start_key, ctx);
        let mut truncated_stream = std::pin::pin!(truncated_stream);

        let mut scratch_left = Vec::new();
@@ -2127,4 +2216,116 @@ mod test {
            assert_eq!(utils::Hex(&scratch_left), utils::Hex(&scratch_right));
        }
    }
+
+    async fn produce_delta_layer(
+        tenant: &Tenant,
+        tline: &Arc<Timeline>,
+        mut deltas: Vec<(Key, Lsn, Value)>,
+        ctx: &RequestContext,
+    ) -> anyhow::Result<ResidentLayer> {
+        deltas.sort_by(|(k1, l1, _), (k2, l2, _)| (k1, l1).cmp(&(k2, l2)));
+        let (key_start, _, _) = deltas.first().unwrap();
+        let (key_max, _, _) = deltas.first().unwrap();
+        let lsn_min = deltas.iter().map(|(_, lsn, _)| lsn).min().unwrap();
+        let lsn_max = deltas.iter().map(|(_, lsn, _)| lsn).max().unwrap();
+        let lsn_end = Lsn(lsn_max.0 + 1);
+        let mut writer = DeltaLayerWriter::new(
+            tenant.conf,
+            tline.timeline_id,
+            tenant.tenant_shard_id,
+            *key_start,
+            (*lsn_min)..lsn_end,
+            ctx,
+        )
+        .await?;
+        let key_end = key_max.next();
+
+        for (key, lsn, value) in deltas {
+            writer.put_value(key, lsn, value, ctx).await?;
+        }
+        let delta_layer = writer.finish(key_end, tline, ctx).await?;
+
+        Ok::<_, anyhow::Error>(delta_layer)
+    }
+
+    async fn assert_delta_iter_equal(
+        delta_iter: &mut DeltaLayerIterator<'_>,
+        expect: &[(Key, Lsn, Value)],
+    ) {
+        let mut expect_iter = expect.iter();
+        loop {
+            let o1 = delta_iter.next().await.unwrap();
+            let o2 = expect_iter.next();
+            assert_eq!(o1.is_some(), o2.is_some());
+            if o1.is_none() && o2.is_none() {
+                break;
+            }
+            let (k1, l1, v1) = o1.unwrap();
+            let (k2, l2, v2) = o2.unwrap();
+            assert_eq!(&k1, k2);
+            assert_eq!(l1, *l2);
+            assert_eq!(&v1, v2);
+        }
+    }
+
+    #[tokio::test]
+    async fn delta_layer_iterator() {
+        use crate::repository::Value;
+        use bytes::Bytes;
+
+        let harness = TenantHarness::create("delta_layer_iterator").unwrap();
+        let (tenant, ctx) = harness.load().await;
+
+        let tline = tenant
+            .create_test_timeline(TIMELINE_ID, Lsn(0x10), DEFAULT_PG_VERSION, &ctx)
+            .await
+            .unwrap();
+
+        fn get_key(id: u32) -> Key {
+            let mut key = Key::from_hex("000000000033333333444444445500000000").unwrap();
+            key.field6 = id;
+            key
+        }
+        const N: usize = 1000;
+        let test_deltas = (0..N)
+            .map(|idx| {
+                (
+                    get_key(idx as u32 / 10),
+                    Lsn(0x10 * ((idx as u64) % 10 + 1)),
+                    Value::Image(Bytes::from(format!("img{idx:05}"))),
+                )
+            })
+            .collect_vec();
+        let resident_layer = produce_delta_layer(&tenant, &tline, test_deltas.clone(), &ctx)
+            .await
+            .unwrap();
+        let delta_layer = resident_layer.get_as_delta(&ctx).await.unwrap();
+        for max_read_size in [1, 1024] {
+            for batch_size in [1, 2, 4, 8, 3, 7, 13] {
+                println!("running with batch_size={batch_size} max_read_size={max_read_size}");
+                // Test if the batch size is correctly determined
+                let mut iter = delta_layer.iter(&ctx);
+                iter.planner = StreamingVectoredReadPlanner::new(max_read_size, batch_size);
+                let mut num_items = 0;
+                for _ in 0..3 {
+                    iter.next_batch().await.unwrap();
+                    num_items += iter.key_values_batch.len();
+                    if max_read_size == 1 {
+                        // every key should be a batch b/c the value is larger than max_read_size
+                        assert_eq!(iter.key_values_batch.len(), 1);
+                    } else {
+                        assert_eq!(iter.key_values_batch.len(), batch_size);
+                    }
+                    if num_items >= N {
+                        break;
+                    }
+                    iter.key_values_batch.clear();
+                }
+                // Test if the result is correct
+                let mut iter = delta_layer.iter(&ctx);
+                iter.planner = StreamingVectoredReadPlanner::new(max_read_size, batch_size);
+                assert_delta_iter_equal(&mut iter, &test_deltas).await;
+            }
+        }
+    }
 }
--- a/pageserver/src/tenant/storage_layer/image_layer.rs
+++ b/pageserver/src/tenant/storage_layer/image_layer.rs
@@ -165,6 +165,7 @@ pub struct ImageLayerInner {
    file_id: FileId,

    max_vectored_read_bytes: Option<MaxVectoredReadBytes>,
+    compressed_reads: bool,
 }

 impl std::fmt::Debug for ImageLayerInner {
@@ -178,7 +179,8 @@ impl std::fmt::Debug for ImageLayerInner {

 impl ImageLayerInner {
    pub(super) async fn dump(&self, ctx: &RequestContext) -> anyhow::Result<()> {
-        let block_reader = FileBlockReader::new(&self.file, self.file_id);
+        let block_reader =
+            FileBlockReader::new_with_compression(&self.file, self.file_id, self.compressed_reads);
        let tree_reader = DiskBtreeReader::<_, KEY_SIZE>::new(
            self.index_start_blk,
            self.index_root_blk,
@@ -266,9 +268,10 @@ impl ImageLayer {
    async fn load_inner(&self, ctx: &RequestContext) -> Result<ImageLayerInner> {
        let path = self.path();

-        let loaded = ImageLayerInner::load(&path, self.desc.image_layer_lsn(), None, None, ctx)
-            .await
-            .and_then(|res| res)?;
+        let loaded =
+            ImageLayerInner::load(&path, self.desc.image_layer_lsn(), None, None, false, ctx)
+                .await
+                .and_then(|res| res)?;

        // not production code
        let actual_layer_name = LayerName::from_str(path.file_name().unwrap()).unwrap();
@@ -377,6 +380,7 @@ impl ImageLayerInner {
        lsn: Lsn,
        summary: Option<Summary>,
        max_vectored_read_bytes: Option<MaxVectoredReadBytes>,
+        support_compressed_reads: bool,
        ctx: &RequestContext,
    ) -> Result<Result<Self, anyhow::Error>, anyhow::Error> {
        let file = match VirtualFile::open(path, ctx).await {
@@ -420,6 +424,7 @@ impl ImageLayerInner {
            file,
            file_id,
            max_vectored_read_bytes,
+            compressed_reads: support_compressed_reads,
            key_range: actual_summary.key_range,
        }))
    }
@@ -430,7 +435,8 @@ impl ImageLayerInner {
        reconstruct_state: &mut ValueReconstructState,
        ctx: &RequestContext,
    ) -> anyhow::Result<ValueReconstructResult> {
-        let block_reader = FileBlockReader::new(&self.file, self.file_id);
+        let block_reader =
+            FileBlockReader::new_with_compression(&self.file, self.file_id, self.compressed_reads);
        let tree_reader =
            DiskBtreeReader::new(self.index_start_blk, self.index_root_blk, &block_reader);

@@ -486,17 +492,18 @@ impl ImageLayerInner {
    }

    /// Load all key-values in the delta layer, should be replaced by an iterator-based interface in the future.
-    #[cfg(test)]
    pub(super) async fn load_key_values(
        &self,
        ctx: &RequestContext,
    ) -> anyhow::Result<Vec<(Key, Lsn, Value)>> {
-        let block_reader = FileBlockReader::new(&self.file, self.file_id);
+        let block_reader =
+            FileBlockReader::new_with_compression(&self.file, self.file_id, self.compressed_reads);
        let tree_reader =
            DiskBtreeReader::new(self.index_start_blk, self.index_root_blk, &block_reader);
        let mut result = Vec::new();
-        let mut stream = Box::pin(tree_reader.get_stream_from(&[0; KEY_SIZE], ctx));
-        let block_reader = FileBlockReader::new(&self.file, self.file_id);
+        let mut stream = Box::pin(tree_reader.into_stream(&[0; KEY_SIZE], ctx));
+        let block_reader =
+            FileBlockReader::new_with_compression(&self.file, self.file_id, self.compressed_reads);
        let cursor = block_reader.block_cursor();
        while let Some(item) = stream.next().await {
            // TODO: dedup code with get_reconstruct_value
@@ -531,7 +538,8 @@ impl ImageLayerInner {
                .into(),
        );

-        let block_reader = FileBlockReader::new(&self.file, self.file_id);
+        let block_reader =
+            FileBlockReader::new_with_compression(&self.file, self.file_id, self.compressed_reads);
        let tree_reader =
            DiskBtreeReader::new(self.index_start_blk, self.index_root_blk, block_reader);

@@ -544,7 +552,7 @@ impl ImageLayerInner {
            let mut search_key: [u8; KEY_SIZE] = [0u8; KEY_SIZE];
            range.start.write_to_byte_slice(&mut search_key);

-            let index_stream = tree_reader.get_stream_from(&search_key, &ctx);
+            let index_stream = tree_reader.clone().into_stream(&search_key, &ctx);
            let mut index_stream = std::pin::pin!(index_stream);

            while let Some(index_entry) = index_stream.next().await {
@@ -689,6 +697,25 @@ impl ImageLayerInner {
            };
        }
    }
+
+    #[cfg(test)]
+    pub(crate) fn iter<'a>(&'a self, ctx: &'a RequestContext) -> ImageLayerIterator<'a> {
+        let block_reader =
+            FileBlockReader::new_with_compression(&self.file, self.file_id, self.compressed_reads);
+        let tree_reader =
+            DiskBtreeReader::new(self.index_start_blk, self.index_root_blk, block_reader);
+        ImageLayerIterator {
+            image_layer: self,
+            ctx,
+            index_iter: tree_reader.iter(&[0; KEY_SIZE], ctx),
+            key_values_batch: std::collections::VecDeque::new(),
+            is_end: false,
+            planner: crate::tenant::vectored_blob_io::StreamingVectoredReadPlanner::new(
+                1024 * 8192, // The default value. Unit tests might use a different value. 1024 * 8K = 8MB buffer.
+                1024,        // The default value. Unit tests might use a different value
+            ),
+        }
+    }
 }

 /// A builder object for constructing a new image layer.
@@ -943,11 +970,77 @@ impl Drop for ImageLayerWriter {
    }
 }

+#[cfg(test)]
+pub struct ImageLayerIterator<'a> {
+    image_layer: &'a ImageLayerInner,
+    ctx: &'a RequestContext,
+    planner: crate::tenant::vectored_blob_io::StreamingVectoredReadPlanner,
+    index_iter: crate::tenant::disk_btree::DiskBtreeIterator<'a>,
+    key_values_batch: std::collections::VecDeque<(Key, Lsn, Value)>,
+    is_end: bool,
+}
+
+#[cfg(test)]
+impl<'a> ImageLayerIterator<'a> {
+    /// Retrieve a batch of key-value pairs into the iterator buffer.
+    async fn next_batch(&mut self) -> anyhow::Result<()> {
+        assert!(self.key_values_batch.is_empty());
+        assert!(!self.is_end);
+
+        let plan = loop {
+            if let Some(res) = self.index_iter.next().await {
+                let (raw_key, offset) = res?;
+                if let Some(batch_plan) = self.planner.handle(
+                    Key::from_slice(&raw_key[..KEY_SIZE]),
+                    self.image_layer.lsn,
+                    offset,
+                    BlobFlag::None,
+                ) {
+                    break batch_plan;
+                }
+            } else {
+                self.is_end = true;
+                let payload_end = self.image_layer.index_start_blk as u64 * PAGE_SZ as u64;
+                break self.planner.handle_range_end(payload_end);
+            }
+        };
+        let vectored_blob_reader = VectoredBlobReader::new(&self.image_layer.file);
+        let mut next_batch = std::collections::VecDeque::new();
+        let buf_size = plan.size();
+        let buf = BytesMut::with_capacity(buf_size);
+        let blobs_buf = vectored_blob_reader
+            .read_blobs(&plan, buf, self.ctx)
+            .await?;
+        let frozen_buf: Bytes = blobs_buf.buf.freeze();
+        for meta in blobs_buf.blobs.iter() {
+            let img_buf = frozen_buf.slice(meta.start..meta.end);
+            next_batch.push_back((meta.meta.key, self.image_layer.lsn, Value::Image(img_buf)));
+        }
+        self.key_values_batch = next_batch;
+        Ok(())
+    }
+
+    pub async fn next(&mut self) -> anyhow::Result<Option<(Key, Lsn, Value)>> {
+        if self.key_values_batch.is_empty() {
+            if self.is_end {
+                return Ok(None);
+            }
+            self.next_batch().await?;
+        }
+        Ok(Some(
+            self.key_values_batch
+                .pop_front()
+                .expect("should not be empty"),
+        ))
+    }
+}
+
 #[cfg(test)]
 mod test {
-    use std::time::Duration;
+    use std::{sync::Arc, time::Duration};

    use bytes::Bytes;
+    use itertools::Itertools;
    use pageserver_api::{
        key::Key,
        shard::{ShardCount, ShardIdentity, ShardNumber, ShardStripeSize},
@@ -959,11 +1052,19 @@ mod test {
    };

    use crate::{
-        tenant::{config::TenantConf, harness::TenantHarness},
+        context::RequestContext,
+        repository::Value,
+        tenant::{
+            config::TenantConf,
+            harness::{TenantHarness, TIMELINE_ID},
+            storage_layer::ResidentLayer,
+            vectored_blob_io::StreamingVectoredReadPlanner,
+            Tenant, Timeline,
+        },
        DEFAULT_PG_VERSION,
    };

-    use super::ImageLayerWriter;
+    use super::{ImageLayerIterator, ImageLayerWriter};

    #[tokio::test]
    async fn image_layer_rewrite() {
@@ -1134,4 +1235,111 @@ mod test {
            }
        }
    }
+
+    async fn produce_image_layer(
+        tenant: &Tenant,
+        tline: &Arc<Timeline>,
+        mut images: Vec<(Key, Bytes)>,
+        lsn: Lsn,
+        ctx: &RequestContext,
+    ) -> anyhow::Result<ResidentLayer> {
+        images.sort();
+        let (key_start, _) = images.first().unwrap();
+        let (key_last, _) = images.last().unwrap();
+        let key_end = key_last.next();
+        let key_range = *key_start..key_end;
+        let mut writer = ImageLayerWriter::new(
+            tenant.conf,
+            tline.timeline_id,
+            tenant.tenant_shard_id,
+            &key_range,
+            lsn,
+            ctx,
+        )
+        .await?;
+
+        for (key, img) in images {
+            writer.put_image(key, img, ctx).await?;
+        }
+        let img_layer = writer.finish(tline, ctx).await?;
+
+        Ok::<_, anyhow::Error>(img_layer)
+    }
+
+    async fn assert_img_iter_equal(
+        img_iter: &mut ImageLayerIterator<'_>,
+        expect: &[(Key, Bytes)],
+        expect_lsn: Lsn,
+    ) {
+        let mut expect_iter = expect.iter();
+        loop {
+            let o1 = img_iter.next().await.unwrap();
+            let o2 = expect_iter.next();
+            match (o1, o2) {
+                (None, None) => break,
+                (Some((k1, l1, v1)), Some((k2, i2))) => {
+                    let Value::Image(i1) = v1 else {
+                        panic!("expect Value::Image")
+                    };
+                    assert_eq!(&k1, k2);
+                    assert_eq!(l1, expect_lsn);
+                    assert_eq!(&i1, i2);
+                }
+                (o1, o2) => panic!("iterators length mismatch: {:?}, {:?}", o1, o2),
+            }
+        }
+    }
+
+    #[tokio::test]
+    async fn image_layer_iterator() {
+        let harness = TenantHarness::create("image_layer_iterator").unwrap();
+        let (tenant, ctx) = harness.load().await;
+
+        let tline = tenant
+            .create_test_timeline(TIMELINE_ID, Lsn(0x10), DEFAULT_PG_VERSION, &ctx)
+            .await
+            .unwrap();
+
+        fn get_key(id: u32) -> Key {
+            let mut key = Key::from_hex("000000000033333333444444445500000000").unwrap();
+            key.field6 = id;
+            key
+        }
+        const N: usize = 1000;
+        let test_imgs = (0..N)
+            .map(|idx| (get_key(idx as u32), Bytes::from(format!("img{idx:05}"))))
+            .collect_vec();
+        let resident_layer =
+            produce_image_layer(&tenant, &tline, test_imgs.clone(), Lsn(0x10), &ctx)
+                .await
+                .unwrap();
+        let img_layer = resident_layer.get_as_image(&ctx).await.unwrap();
+        for max_read_size in [1, 1024] {
+            for batch_size in [1, 2, 4, 8, 3, 7, 13] {
+                println!("running with batch_size={batch_size} max_read_size={max_read_size}");
+                // Test if the batch size is correctly determined
+                let mut iter = img_layer.iter(&ctx);
+                iter.planner = StreamingVectoredReadPlanner::new(max_read_size, batch_size);
+                let mut num_items = 0;
+                for _ in 0..3 {
+                    iter.next_batch().await.unwrap();
+                    num_items += iter.key_values_batch.len();
+                    if max_read_size == 1 {
+                        // every key should be a batch b/c the value is larger than max_read_size
+                        assert_eq!(iter.key_values_batch.len(), 1);
+                    } else {
+                        assert_eq!(iter.key_values_batch.len(), batch_size);
+                    }
+                    if num_items >= N {
+                        break;
+                    }
+                    iter.key_values_batch.clear();
+                }
+                // Test if the result is correct
+                let mut iter = img_layer.iter(&ctx);
+                iter.planner = StreamingVectoredReadPlanner::new(max_read_size, batch_size);
+                assert_img_iter_equal(&mut iter, &test_imgs, Lsn(0x10)).await;
+            }
+        }
+    }
 }
--- a/pageserver/src/tenant/storage_layer/inmemory_layer.rs
+++ b/pageserver/src/tenant/storage_layer/inmemory_layer.rs
@@ -6,13 +6,14 @@
 //!
 use crate::config::PageServerConf;
 use crate::context::{PageContentKind, RequestContext, RequestContextBuilder};
+use crate::page_cache::PAGE_SZ;
 use crate::repository::{Key, Value};
-use crate::tenant::block_io::BlockReader;
+use crate::tenant::block_io::{BlockCursor, BlockReader, BlockReaderRef};
 use crate::tenant::ephemeral_file::EphemeralFile;
 use crate::tenant::storage_layer::ValueReconstructResult;
 use crate::tenant::timeline::GetVectoredError;
 use crate::tenant::{PageReconstructError, Timeline};
-use crate::{page_cache, walrecord};
+use crate::{l0_flush, page_cache, walrecord};
 use anyhow::{anyhow, ensure, Result};
 use pageserver_api::keyspace::KeySpace;
 use pageserver_api::models::InMemoryLayerInfo;
@@ -410,6 +411,7 @@ impl InMemoryLayer {
                continue;
            }

+            // TODO: this uses the page cache => https://github.com/neondatabase/neon/issues/8183
            let buf = reader.read_blob(block_read.block_offset, &ctx).await;
            if let Err(e) = buf {
                reconstruct_state
@@ -620,20 +622,25 @@ impl InMemoryLayer {
        // rare though, so we just accept the potential latency hit for now.
        let inner = self.inner.read().await;

+        let l0_flush_global_state = timeline.l0_flush_global_state.inner().clone();
+        use l0_flush::Inner;
+        let _concurrency_permit = match &*l0_flush_global_state {
+            Inner::PageCached => None,
+            Inner::Direct { semaphore, .. } => Some(semaphore.acquire().await),
+        };
+
        let end_lsn = *self.end_lsn.get().unwrap();

-        let keys: Vec<_> = if let Some(key_range) = key_range {
+        let key_count = if let Some(key_range) = key_range {
            inner
                .index
                .iter()
                .filter(|(k, _)| key_range.contains(k))
-                .map(|(k, m)| (k.to_i128(), m))
-                .collect()
+                .count()
        } else {
-            inner.index.iter().map(|(k, m)| (k.to_i128(), m)).collect()
+            inner.index.len()
        };
-
-        if keys.is_empty() {
+        if key_count == 0 {
            return Ok(None);
        }

@@ -647,28 +654,77 @@ impl InMemoryLayer {
        )
        .await?;

-        let mut buf = Vec::new();
+        match &*l0_flush_global_state {
+            l0_flush::Inner::PageCached => {
+                let ctx = RequestContextBuilder::extend(ctx)
+                    .page_content_kind(PageContentKind::InMemoryLayer)
+                    .build();

-        let cursor = inner.file.block_cursor();
+                let mut buf = Vec::new();

-        let ctx = RequestContextBuilder::extend(ctx)
-            .page_content_kind(PageContentKind::InMemoryLayer)
-            .build();
-        for (key, vec_map) in inner.index.iter() {
-            // Write all page versions
-            for (lsn, pos) in vec_map.as_slice() {
-                cursor.read_blob_into_buf(*pos, &mut buf, &ctx).await?;
-                let will_init = Value::des(&buf)?.will_init();
-                let res;
-                (buf, res) = delta_layer_writer
-                    .put_value_bytes(*key, *lsn, buf, will_init, &ctx)
-                    .await;
-                res?;
+                let cursor = inner.file.block_cursor();
+
+                for (key, vec_map) in inner.index.iter() {
+                    // Write all page versions
+                    for (lsn, pos) in vec_map.as_slice() {
+                        cursor.read_blob_into_buf(*pos, &mut buf, &ctx).await?;
+                        let will_init = Value::des(&buf)?.will_init();
+                        let res;
+                        (buf, res) = delta_layer_writer
+                            .put_value_bytes(*key, *lsn, buf, will_init, &ctx)
+                            .await;
+                        res?;
+                    }
+                }
+            }
+            l0_flush::Inner::Direct { .. } => {
+                let file_contents: Vec<u8> = inner.file.load_to_vec(ctx).await?;
+                assert_eq!(
+                    file_contents.len() % PAGE_SZ,
+                    0,
+                    "needed by BlockReaderRef::Slice"
+                );
+                assert_eq!(file_contents.len(), {
+                    let written = usize::try_from(inner.file.len()).unwrap();
+                    if written % PAGE_SZ == 0 {
+                        written
+                    } else {
+                        written.checked_add(PAGE_SZ - (written % PAGE_SZ)).unwrap()
+                    }
+                });
+
+                let cursor = BlockCursor::new(BlockReaderRef::Slice(&file_contents));
+
+                let mut buf = Vec::new();
+
+                for (key, vec_map) in inner.index.iter() {
+                    // Write all page versions
+                    for (lsn, pos) in vec_map.as_slice() {
+                        // TODO: once we have blob lengths in the in-memory index, we can
+                        // 1. get rid of the blob_io / BlockReaderRef::Slice business and
+                        // 2. load the file contents into a Bytes and
+                        // 3. the use `Bytes::slice` to get the `buf` that is our blob
+                        // 4. pass that `buf` into `put_value_bytes`
+                        // => https://github.com/neondatabase/neon/issues/8183
+                        cursor.read_blob_into_buf(*pos, &mut buf, ctx).await?;
+                        let will_init = Value::des(&buf)?.will_init();
+                        let res;
+                        (buf, res) = delta_layer_writer
+                            .put_value_bytes(*key, *lsn, buf, will_init, ctx)
+                            .await;
+                        res?;
+                    }
+                }
+
+                // Hold the permit until the IO is done; if we didn't, one could drop this future,
+                // thereby releasing the permit, but the Vec<u8> remains allocated until the IO completes.
+                // => we'd have more concurrenct Vec<u8> than allowed as per the semaphore.
+                drop(_concurrency_permit);
            }
        }

        // MAX is used here because we identify L0 layers by full key range
-        let delta_layer = delta_layer_writer.finish(Key::MAX, timeline, &ctx).await?;
+        let delta_layer = delta_layer_writer.finish(Key::MAX, timeline, ctx).await?;
        Ok(Some(delta_layer))
    }
 }
--- a/pageserver/src/tenant/storage_layer/layer.rs
+++ b/pageserver/src/tenant/storage_layer/layer.rs
@@ -93,16 +93,12 @@ pub(crate) struct Layer(Arc<LayerInner>);

 impl std::fmt::Display for Layer {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-        if matches!(self.0.generation, Generation::Broken) {
-            write!(f, "{}-broken", self.layer_desc().short_id())
-        } else {
-            write!(
-                f,
-                "{}{}",
-                self.layer_desc().short_id(),
-                self.0.generation.get_suffix()
-            )
-        }
+        write!(
+            f,
+            "{}{}",
+            self.layer_desc().short_id(),
+            self.0.generation.get_suffix()
+        )
    }
 }

@@ -389,7 +385,6 @@ impl Layer {
    }

    /// Get all key/values in the layer. Should be replaced with an iterator-based API in the future.
-    #[cfg(test)]
    pub(crate) async fn load_key_values(
        &self,
        ctx: &RequestContext,
@@ -1101,19 +1096,10 @@ impl LayerInner {

        match rx.await {
            Ok(Ok(res)) => Ok(res),
-            Ok(Err(e)) => {
-                // sleep already happened in the spawned task, if it was not cancelled
-                match e.downcast_ref::<remote_storage::DownloadError>() {
-                    // If the download failed due to its cancellation token,
-                    // propagate the cancellation error upstream.
-                    Some(remote_storage::DownloadError::Cancelled) => {
-                        Err(DownloadError::DownloadCancelled)
-                    }
-                    // FIXME: this is not embedding the error because historically it would had
-                    // been output to compute, however that is no longer the case.
-                    _ => Err(DownloadError::DownloadFailed),
-                }
+            Ok(Err(remote_storage::DownloadError::Cancelled)) => {
+                Err(DownloadError::DownloadCancelled)
            }
+            Ok(Err(_)) => Err(DownloadError::DownloadFailed),
            Err(_gone) => Err(DownloadError::DownloadCancelled),
        }
    }
@@ -1123,7 +1109,7 @@ impl LayerInner {
        timeline: Arc<Timeline>,
        permit: heavier_once_cell::InitPermit,
        ctx: &RequestContext,
-    ) -> anyhow::Result<Arc<DownloadedLayer>> {
+    ) -> Result<Arc<DownloadedLayer>, remote_storage::DownloadError> {
        let result = timeline
            .remote_client
            .download_layer_file(
@@ -1699,6 +1685,7 @@ impl DownloadedLayer {
                    lsn,
                    summary,
                    Some(owner.conf.max_vectored_read_bytes),
+                    owner.conf.image_compression.allow_decompression(),
                    ctx,
                )
                .await
@@ -1774,7 +1761,6 @@ impl DownloadedLayer {
        }
    }

-    #[cfg(test)]
    async fn load_key_values(
        &self,
        owner: &Arc<LayerInner>,
@@ -1905,7 +1891,7 @@ impl ResidentLayer {
    }

    #[cfg(test)]
-    pub(crate) async fn as_delta(
+    pub(crate) async fn get_as_delta(
        &self,
        ctx: &RequestContext,
    ) -> anyhow::Result<&delta_layer::DeltaLayerInner> {
@@ -1915,6 +1901,18 @@ impl ResidentLayer {
            Image(_) => Err(anyhow::anyhow!("image layer")),
        }
    }
+
+    #[cfg(test)]
+    pub(crate) async fn get_as_image(
+        &self,
+        ctx: &RequestContext,
+    ) -> anyhow::Result<&image_layer::ImageLayerInner> {
+        use LayerKind::*;
+        match self.downloaded.get(&self.owner.0, ctx).await? {
+            Image(ref d) => Ok(d),
+            Delta(_) => Err(anyhow::anyhow!("delta layer")),
+        }
+    }
 }

 impl AsLayerDesc for ResidentLayer {
--- a/pageserver/src/tenant/timeline.rs
+++ b/pageserver/src/tenant/timeline.rs
@@ -14,6 +14,7 @@ use anyhow::{anyhow, bail, ensure, Context, Result};
 use arc_swap::ArcSwap;
 use bytes::Bytes;
 use camino::Utf8Path;
+use chrono::{DateTime, Utc};
 use enumset::EnumSet;
 use fail::fail_point;
 use once_cell::sync::Lazy;
@@ -65,7 +66,6 @@ use std::{
    ops::{Deref, Range},
 };

-use crate::metrics::GetKind;
 use crate::pgdatadir_mapping::MAX_AUX_FILE_V2_DELTAS;
 use crate::{
    aux_file::AuxFileSizeEstimator,
@@ -90,6 +90,10 @@ use crate::{
 use crate::{
    disk_usage_eviction_task::EvictionCandidate, tenant::storage_layer::delta_layer::DeltaEntry,
 };
+use crate::{
+    l0_flush::{self, L0FlushGlobalState},
+    metrics::GetKind,
+};
 use crate::{
    metrics::ScanLatencyOngoingRecording, tenant::timeline::logical_size::CurrentLogicalSize,
 };
@@ -208,6 +212,7 @@ pub struct TimelineResources {
    pub timeline_get_throttle: Arc<
        crate::tenant::throttle::Throttle<&'static crate::metrics::tenant_throttling::TimelineGet>,
    >,
+    pub l0_flush_global_state: l0_flush::L0FlushGlobalState,
 }

 pub(crate) struct AuxFilesState {
@@ -360,6 +365,7 @@ pub struct Timeline {
    repartition_threshold: u64,

    last_image_layer_creation_check_at: AtomicLsn,
+    last_image_layer_creation_check_instant: std::sync::Mutex<Option<Instant>>,

    /// Current logical size of the "datadir", at the last LSN.
    current_logical_size: LogicalSize,
@@ -433,6 +439,8 @@ pub struct Timeline {
    /// in the future, add `extra_test_sparse_keyspace` if necessary.
    #[cfg(test)]
    pub(crate) extra_test_dense_keyspace: ArcSwap<KeySpace>,
+
+    pub(crate) l0_flush_global_state: L0FlushGlobalState,
 }

 pub struct WalReceiverInfo {
@@ -457,6 +465,9 @@ pub(crate) struct GcInfo {

    /// Leases granted to particular LSNs.
    pub(crate) leases: BTreeMap<Lsn, LsnLease>,
+
+    /// Whether our branch point is within our ancestor's PITR interval (for cost estimation)
+    pub(crate) within_ancestor_pitr: bool,
 }

 impl GcInfo {
@@ -686,6 +697,7 @@ pub enum GetLogicalSizePriority {
 pub(crate) enum CompactFlags {
    ForceRepartition,
    ForceImageLayerCreation,
+    EnhancedGcBottomMostCompaction,
 }

 impl std::fmt::Debug for Timeline {
@@ -844,6 +856,18 @@ impl Timeline {
            .map(|ancestor| ancestor.timeline_id)
    }

+    /// Get the bytes written since the PITR cutoff on this branch, and
+    /// whether this branch's ancestor_lsn is within its parent's PITR.
+    pub(crate) fn get_pitr_history_stats(&self) -> (u64, bool) {
+        let gc_info = self.gc_info.read().unwrap();
+        let history = self
+            .get_last_record_lsn()
+            .checked_sub(gc_info.cutoffs.pitr)
+            .unwrap_or(Lsn(0))
+            .0;
+        (history, gc_info.within_ancestor_pitr)
+    }
+
    /// Lock and get timeline's GC cutoff
    pub(crate) fn get_latest_gc_cutoff_lsn(&self) -> RcuReadGuard<Lsn> {
        self.latest_gc_cutoff_lsn.read()
@@ -995,6 +1019,7 @@ impl Timeline {
    }

    pub(crate) const MAX_GET_VECTORED_KEYS: u64 = 32;
+    pub(crate) const VEC_GET_LAYERS_VISITED_WARN_THRESH: f64 = 512.0;

    /// Look up multiple page versions at a given LSN
    ///
@@ -1096,7 +1121,6 @@ impl Timeline {
    /// scan iterator interface. We could optimize this interface later to avoid some checks in the vectored
    /// get path to maintain and split the probing and to-be-probe keyspace. We also need to ensure that
    /// the scan operation will not cause OOM in the future.
-    #[allow(dead_code)]
    pub(crate) async fn scan(
        &self,
        keyspace: KeySpace,
@@ -1228,7 +1252,7 @@ impl Timeline {
        let get_data_timer = crate::metrics::GET_RECONSTRUCT_DATA_TIME
            .for_get_kind(get_kind)
            .start_timer();
-        self.get_vectored_reconstruct_data(keyspace, lsn, reconstruct_state, ctx)
+        self.get_vectored_reconstruct_data(keyspace.clone(), lsn, reconstruct_state, ctx)
            .await?;
        get_data_timer.stop_and_record();

@@ -1258,11 +1282,25 @@ impl Timeline {
        // (this is a requirement, not a bug). Skip updating the metric in these cases
        // to avoid infinite results.
        if !results.is_empty() {
+            let avg = layers_visited as f64 / results.len() as f64;
+            if avg >= Self::VEC_GET_LAYERS_VISITED_WARN_THRESH {
+                use utils::rate_limit::RateLimit;
+                static LOGGED: Lazy<Mutex<RateLimit>> =
+                    Lazy::new(|| Mutex::new(RateLimit::new(Duration::from_secs(60))));
+                let mut rate_limit = LOGGED.lock().unwrap();
+                rate_limit.call(|| {
+                    tracing::info!(
+                      shard_id = %self.tenant_shard_id.shard_slug(),
+                      lsn = %lsn,
+                      "Vectored read for {} visited {} layers on average per key and {} in total. {}/{} pages were returned",
+                      keyspace, avg, layers_visited, results.len(), keyspace.total_raw_size());
+                });
+            }
+
            // Note that this is an approximation. Tracking the exact number of layers visited
            // per key requires virtually unbounded memory usage and is inefficient
            // (i.e. segment tree tracking each range queried from a layer)
-            crate::metrics::VEC_READ_NUM_LAYERS_VISITED
-                .observe(layers_visited as f64 / results.len() as f64);
+            crate::metrics::VEC_READ_NUM_LAYERS_VISITED.observe(avg);
        }

        Ok(results)
@@ -1554,7 +1592,13 @@ impl Timeline {
                    let existing_lease = occupied.get_mut();
                    if valid_until > existing_lease.valid_until {
                        existing_lease.valid_until = valid_until;
+                        let dt: DateTime<Utc> = valid_until.into();
+                        info!("lease extended to {}", dt);
+                    } else {
+                        let dt: DateTime<Utc> = existing_lease.valid_until.into();
+                        info!("existing lease covers greater length, valid until {}", dt);
                    }
+
                    existing_lease.clone()
                } else {
                    // Reject already GC-ed LSN (lsn < latest_gc_cutoff)
@@ -1563,6 +1607,8 @@ impl Timeline {
                        bail!("tried to request a page version that was garbage collected. requested at {} gc cutoff {}", lsn, *latest_gc_cutoff_lsn);
                    }

+                    let dt: DateTime<Utc> = valid_until.into();
+                    info!("lease created, valid until {}", dt);
                    entry.or_insert(LsnLease { valid_until }).clone()
                }
            };
@@ -2339,6 +2385,7 @@ impl Timeline {
                )),
                repartition_threshold: 0,
                last_image_layer_creation_check_at: AtomicLsn::new(0),
+                last_image_layer_creation_check_instant: Mutex::new(None),

                last_received_wal: Mutex::new(None),
                rel_size_cache: RwLock::new(RelSizeCache {
@@ -2376,6 +2423,8 @@ impl Timeline {

                #[cfg(test)]
                extra_test_dense_keyspace: ArcSwap::new(Arc::new(KeySpace::default())),
+
+                l0_flush_global_state: resources.l0_flush_global_state,
            };
            result.repartition_threshold =
                result.get_checkpoint_distance() / REPARTITION_FREQ_IN_CHECKPOINT_DISTANCE;
@@ -4417,6 +4466,58 @@ impl Timeline {
        }
    }

+    /// Predicate function which indicates whether we should check if new image layers
+    /// are required. Since checking if new image layers are required is expensive in
+    /// terms of CPU, we only do it in the following cases:
+    /// 1. If the timeline has ingested sufficient WAL to justify the cost
+    /// 2. If enough time has passed since the last check
+    /// 2.1. For large tenants, we wish to perform the check more often since they
+    /// suffer from the lack of image layers
+    /// 2.2. For small tenants (that can mostly fit in RAM), we use a much longer interval
+    fn should_check_if_image_layers_required(self: &Arc<Timeline>, lsn: Lsn) -> bool {
+        const LARGE_TENANT_THRESHOLD: u64 = 2 * 1024 * 1024 * 1024;
+
+        let last_checks_at = self.last_image_layer_creation_check_at.load();
+        let distance = lsn
+            .checked_sub(last_checks_at)
+            .expect("Attempt to compact with LSN going backwards");
+        let min_distance =
+            self.get_image_layer_creation_check_threshold() as u64 * self.get_checkpoint_distance();
+
+        let distance_based_decision = distance.0 >= min_distance;
+
+        let mut time_based_decision = false;
+        let mut last_check_instant = self.last_image_layer_creation_check_instant.lock().unwrap();
+        if let CurrentLogicalSize::Exact(logical_size) = self.current_logical_size.current_size() {
+            let check_required_after = if Into::<u64>::into(&logical_size) >= LARGE_TENANT_THRESHOLD
+            {
+                self.get_checkpoint_timeout()
+            } else {
+                Duration::from_secs(3600 * 48)
+            };
+
+            time_based_decision = match *last_check_instant {
+                Some(last_check) => {
+                    let elapsed = last_check.elapsed();
+                    elapsed >= check_required_after
+                }
+                None => true,
+            };
+        }
+
+        // Do the expensive delta layer counting only if this timeline has ingested sufficient
+        // WAL since the last check or a checkpoint timeout interval has elapsed since the last
+        // check.
+        let decision = distance_based_decision || time_based_decision;
+
+        if decision {
+            self.last_image_layer_creation_check_at.store(lsn);
+            *last_check_instant = Some(Instant::now());
+        }
+
+        decision
+    }
+
    #[tracing::instrument(skip_all, fields(%lsn, %mode))]
    async fn create_image_layers(
        self: &Arc<Timeline>,
@@ -4439,22 +4540,7 @@ impl Timeline {
        // image layers  <100000000..100000099> and <200000000..200000199> are not completely covering it.
        let mut start = Key::MIN;

-        let check_for_image_layers = {
-            let last_checks_at = self.last_image_layer_creation_check_at.load();
-            let distance = lsn
-                .checked_sub(last_checks_at)
-                .expect("Attempt to compact with LSN going backwards");
-            let min_distance = self.get_image_layer_creation_check_threshold() as u64
-                * self.get_checkpoint_distance();
-
-            // Skip the expensive delta layer counting if this timeline has not ingested sufficient
-            // WAL since the last check.
-            distance.0 >= min_distance
-        };
-
-        if check_for_image_layers {
-            self.last_image_layer_creation_check_at.store(lsn);
-        }
+        let check_for_image_layers = self.should_check_if_image_layers_required(lsn);

        for partition in partitioning.parts.iter() {
            let img_range = start..partition.ranges.last().unwrap().end;
@@ -4711,6 +4797,42 @@ impl DurationRecorder {
    }
 }

+/// Descriptor for a delta layer used in testing infra. The start/end key/lsn range of the
+/// delta layer might be different from the min/max key/lsn in the delta layer. Therefore,
+/// the layer descriptor requires the user to provide the ranges, which should cover all
+/// keys specified in the `data` field.
+#[cfg(test)]
+pub struct DeltaLayerTestDesc {
+    pub lsn_range: Range<Lsn>,
+    pub key_range: Range<Key>,
+    pub data: Vec<(Key, Lsn, Value)>,
+}
+
+#[cfg(test)]
+impl DeltaLayerTestDesc {
+    #[allow(dead_code)]
+    pub fn new(lsn_range: Range<Lsn>, key_range: Range<Key>, data: Vec<(Key, Lsn, Value)>) -> Self {
+        Self {
+            lsn_range,
+            key_range,
+            data,
+        }
+    }
+
+    pub fn new_with_inferred_key_range(
+        lsn_range: Range<Lsn>,
+        data: Vec<(Key, Lsn, Value)>,
+    ) -> Self {
+        let key_min = data.iter().map(|(key, _, _)| key).min().unwrap();
+        let key_max = data.iter().map(|(key, _, _)| key).max().unwrap();
+        Self {
+            key_range: (*key_min)..(key_max.next()),
+            lsn_range,
+            data,
+        }
+    }
+}
+
 impl Timeline {
    async fn finish_compact_batch(
        self: &Arc<Self>,
@@ -5481,12 +5603,12 @@ impl Timeline {
        }
        images.sort_unstable_by(|(ka, _), (kb, _)| ka.cmp(kb));
        let min_key = *images.first().map(|(k, _)| k).unwrap();
-        let max_key = images.last().map(|(k, _)| k).unwrap().next();
+        let end_key = images.last().map(|(k, _)| k).unwrap().next();
        let mut image_layer_writer = ImageLayerWriter::new(
            self.conf,
            self.timeline_id,
            self.tenant_shard_id,
-            &(min_key..max_key),
+            &(min_key..end_key),
            lsn,
            ctx,
        )
@@ -5511,37 +5633,65 @@ impl Timeline {
    #[cfg(test)]
    pub(super) async fn force_create_delta_layer(
        self: &Arc<Timeline>,
-        mut deltas: Vec<(Key, Lsn, Value)>,
+        mut deltas: DeltaLayerTestDesc,
        check_start_lsn: Option<Lsn>,
        ctx: &RequestContext,
    ) -> anyhow::Result<()> {
        let last_record_lsn = self.get_last_record_lsn();
-        deltas.sort_unstable_by(|(ka, la, _), (kb, lb, _)| (ka, la).cmp(&(kb, lb)));
-        let min_key = *deltas.first().map(|(k, _, _)| k).unwrap();
-        let max_key = deltas.last().map(|(k, _, _)| k).unwrap().next();
-        let min_lsn = *deltas.iter().map(|(_, lsn, _)| lsn).min().unwrap();
-        let max_lsn = *deltas.iter().map(|(_, lsn, _)| lsn).max().unwrap();
+        deltas
+            .data
+            .sort_unstable_by(|(ka, la, _), (kb, lb, _)| (ka, la).cmp(&(kb, lb)));
+        assert!(deltas.data.first().unwrap().0 >= deltas.key_range.start);
+        assert!(deltas.data.last().unwrap().0 < deltas.key_range.end);
+        for (_, lsn, _) in &deltas.data {
+            assert!(deltas.lsn_range.start <= *lsn && *lsn < deltas.lsn_range.end);
+        }
        assert!(
-            max_lsn <= last_record_lsn,
-            "advance last record lsn before inserting a layer, max_lsn={max_lsn}, last_record_lsn={last_record_lsn}"
+            deltas.lsn_range.end <= last_record_lsn,
+            "advance last record lsn before inserting a layer, end_lsn={}, last_record_lsn={}",
+            deltas.lsn_range.end,
+            last_record_lsn
        );
-        let end_lsn = Lsn(max_lsn.0 + 1);
        if let Some(check_start_lsn) = check_start_lsn {
-            assert!(min_lsn >= check_start_lsn);
+            assert!(deltas.lsn_range.start >= check_start_lsn);
+        }
+        // check if the delta layer does not violate the LSN invariant, the legacy compaction should always produce a batch of
+        // layers of the same start/end LSN, and so should the force inserted layer
+        {
+            /// Checks if a overlaps with b, assume a/b = [start, end).
+            pub fn overlaps_with<T: Ord>(a: &Range<T>, b: &Range<T>) -> bool {
+                !(a.end <= b.start || b.end <= a.start)
+            }
+
+            let guard = self.layers.read().await;
+            for layer in guard.layer_map().iter_historic_layers() {
+                if layer.is_delta()
+                    && overlaps_with(&layer.lsn_range, &deltas.lsn_range)
+                    && layer.lsn_range != deltas.lsn_range
+                {
+                    // If a delta layer overlaps with another delta layer AND their LSN range is not the same, panic
+                    panic!(
+                        "inserted layer violates delta layer LSN invariant: current_lsn_range={}..{}, conflict_lsn_range={}..{}",
+                        deltas.lsn_range.start, deltas.lsn_range.end, layer.lsn_range.start, layer.lsn_range.end
+                    );
+                }
+            }
        }
        let mut delta_layer_writer = DeltaLayerWriter::new(
            self.conf,
            self.timeline_id,
            self.tenant_shard_id,
-            min_key,
-            min_lsn..end_lsn,
+            deltas.key_range.start,
+            deltas.lsn_range,
            ctx,
        )
        .await?;
-        for (key, lsn, val) in deltas {
+        for (key, lsn, val) in deltas.data {
            delta_layer_writer.put_value(key, lsn, val, ctx).await?;
        }
-        let delta_layer = delta_layer_writer.finish(max_key, self, ctx).await?;
+        let delta_layer = delta_layer_writer
+            .finish(deltas.key_range.end, self, ctx)
+            .await?;

        {
            let mut guard = self.layers.write().await;
--- a/pageserver/src/tenant/timeline/compaction.rs
+++ b/pageserver/src/tenant/timeline/compaction.rs
@@ -47,10 +47,14 @@ impl Timeline {
    /// TODO: cancellation
    pub(crate) async fn compact_legacy(
        self: &Arc<Self>,
-        _cancel: &CancellationToken,
+        cancel: &CancellationToken,
        flags: EnumSet<CompactFlags>,
        ctx: &RequestContext,
    ) -> Result<(), CompactionError> {
+        if flags.contains(CompactFlags::EnhancedGcBottomMostCompaction) {
+            return self.compact_with_gc(cancel, ctx).await;
+        }
+
        // High level strategy for compaction / image creation:
        //
        // 1. First, calculate the desired "partitioning" of the
@@ -959,13 +963,20 @@ impl Timeline {
    /// the GC horizon without considering retain_lsns. Then, it does a full compaction over all these delta
    /// layers and image layers, which generates image layers on the gc horizon, drop deltas below gc horizon,
    /// and create delta layers with all deltas >= gc horizon.
-    #[cfg(test)]
    pub(crate) async fn compact_with_gc(
        self: &Arc<Self>,
        _cancel: &CancellationToken,
        ctx: &RequestContext,
    ) -> Result<(), CompactionError> {
        use crate::tenant::storage_layer::ValueReconstructState;
+        use std::collections::BTreeSet;
+
+        info!("running enhanced gc bottom-most compaction");
+
+        scopeguard::defer! {
+            info!("done enhanced gc bottom-most compaction");
+        };
+
        // Step 0: pick all delta layers + image layers below/intersect with the GC horizon.
        // The layer selection has the following properties:
        // 1. If a layer is in the selection, all layers below it are in the selection.
@@ -974,6 +985,11 @@ impl Timeline {
            let guard = self.layers.read().await;
            let layers = guard.layer_map();
            let gc_info = self.gc_info.read().unwrap();
+            if !gc_info.retain_lsns.is_empty() || !gc_info.leases.is_empty() {
+                return Err(CompactionError::Other(anyhow!(
+                    "enhanced legacy compaction currently does not support retain_lsns (branches)"
+                )));
+            }
            let gc_cutoff = Lsn::min(gc_info.cutoffs.horizon, gc_info.cutoffs.pitr);
            let mut selected_layers = Vec::new();
            // TODO: consider retain_lsns
@@ -985,21 +1001,36 @@ impl Timeline {
            }
            (selected_layers, gc_cutoff)
        };
+        info!(
+            "picked {} layers for compaction with gc_cutoff={}",
+            layer_selection.len(),
+            gc_cutoff
+        );
        // Step 1: (In the future) construct a k-merge iterator over all layers. For now, simply collect all keys + LSNs.
+        // Also, collect the layer information to decide when to split the new delta layers.
        let mut all_key_values = Vec::new();
+        let mut delta_split_points = BTreeSet::new();
        for layer in &layer_selection {
            all_key_values.extend(layer.load_key_values(ctx).await?);
+            let desc = layer.layer_desc();
+            if desc.is_delta() {
+                // TODO: is it correct to only record split points for deltas intersecting with the GC horizon? (exclude those below/above the horizon)
+                // so that we can avoid having too many small delta layers.
+                let key_range = desc.get_key_range();
+                delta_split_points.insert(key_range.start);
+                delta_split_points.insert(key_range.end);
+            }
        }
        // Key small to large, LSN low to high, if the same LSN has both image and delta due to the merge of delta layers and
-        // image layers, make image appear later than delta.
+        // image layers, make image appear before than delta.
        struct ValueWrapper<'a>(&'a crate::repository::Value);
        impl Ord for ValueWrapper<'_> {
            fn cmp(&self, other: &Self) -> std::cmp::Ordering {
                use crate::repository::Value;
                use std::cmp::Ordering;
                match (self.0, other.0) {
-                    (Value::Image(_), Value::WalRecord(_)) => Ordering::Greater,
-                    (Value::WalRecord(_), Value::Image(_)) => Ordering::Less,
+                    (Value::Image(_), Value::WalRecord(_)) => Ordering::Less,
+                    (Value::WalRecord(_), Value::Image(_)) => Ordering::Greater,
                    _ => Ordering::Equal,
                }
            }
@@ -1018,13 +1049,6 @@ impl Timeline {
        all_key_values.sort_by(|(k1, l1, v1), (k2, l2, v2)| {
            (k1, l1, ValueWrapper(v1)).cmp(&(k2, l2, ValueWrapper(v2)))
        });
-        let max_lsn = all_key_values
-            .iter()
-            .map(|(_, lsn, _)| lsn)
-            .max()
-            .copied()
-            .unwrap()
-            + 1;
        // Step 2: Produce images+deltas. TODO: ensure newly-produced delta does not overlap with other deltas.
        // Data of the same key.
        let mut accumulated_values = Vec::new();
@@ -1043,14 +1067,24 @@ impl Timeline {
            // We have a list of deltas/images. We want to create image layers while collect garbages.
            for (key, lsn, val) in accumulated_values.iter().rev() {
                if *lsn > horizon {
-                    keys_above_horizon.push((*key, *lsn, val.clone())); // TODO: ensure one LSN corresponds to either delta or image instead of both
+                    if let Some((_, prev_lsn, _)) = keys_above_horizon.last_mut() {
+                        if *prev_lsn == *lsn {
+                            // The case that we have an LSN with both data from the delta layer and the image layer. As
+                            // `ValueWrapper` ensures that an image is ordered before a delta at the same LSN, we simply
+                            // drop this delta and keep the image.
+                            //
+                            // For example, we have delta layer key1@0x10, key1@0x20, and image layer key1@0x10, we will
+                            // keep the image for key1@0x10 and the delta for key1@0x20. key1@0x10 delta will be simply
+                            // dropped.
+                            continue;
+                        }
+                    }
+                    keys_above_horizon.push((*key, *lsn, val.clone()));
                } else if *lsn <= horizon {
                    match val {
                        crate::repository::Value::Image(image) => {
-                            if lsn <= &horizon {
-                                base_image = Some((*lsn, image.clone()));
-                                break;
-                            }
+                            base_image = Some((*lsn, image.clone()));
+                            break;
                        }
                        crate::repository::Value::WalRecord(wal) => {
                            delta_above_base_image.push((*lsn, wal.clone()));
@@ -1058,7 +1092,7 @@ impl Timeline {
                    }
                }
            }
-            delta_above_base_image.reverse();
+            // do not reverse delta_above_base_image, reconstruct state expects reversely-ordered records
            keys_above_horizon.reverse();
            let state = ValueReconstructState {
                img: base_image,
@@ -1068,15 +1102,59 @@ impl Timeline {
            Ok((keys_above_horizon, img))
        }

-        let mut delta_layer_writer = DeltaLayerWriter::new(
-            self.conf,
-            self.timeline_id,
-            self.tenant_shard_id,
-            all_key_values.first().unwrap().0,
-            gc_cutoff..max_lsn, // TODO: off by one?
-            ctx,
-        )
-        .await?;
+        async fn flush_deltas(
+            deltas: &mut Vec<(Key, Lsn, crate::repository::Value)>,
+            last_key: Key,
+            delta_split_points: &[Key],
+            current_delta_split_point: &mut usize,
+            tline: &Arc<Timeline>,
+            gc_cutoff: Lsn,
+            ctx: &RequestContext,
+        ) -> anyhow::Result<Option<ResidentLayer>> {
+            // Check if we need to split the delta layer. We split at the original delta layer boundary to avoid
+            // overlapping layers.
+            //
+            // If we have a structure like this:
+            //
+            // | Delta 1 |         | Delta 4 |
+            // |---------| Delta 2 |---------|
+            // | Delta 3 |         | Delta 5 |
+            //
+            // And we choose to compact delta 2+3+5. We will get an overlapping delta layer with delta 1+4.
+            // A simple solution here is to split the delta layers using the original boundary, while this
+            // might produce a lot of small layers. This should be improved and fixed in the future.
+            let mut need_split = false;
+            while *current_delta_split_point < delta_split_points.len()
+                && last_key >= delta_split_points[*current_delta_split_point]
+            {
+                *current_delta_split_point += 1;
+                need_split = true;
+            }
+            if !need_split {
+                return Ok(None);
+            }
+            let deltas = std::mem::take(deltas);
+            if deltas.is_empty() {
+                return Ok(None);
+            }
+            let end_lsn = deltas.iter().map(|(_, lsn, _)| lsn).max().copied().unwrap() + 1;
+            let mut delta_layer_writer = DeltaLayerWriter::new(
+                tline.conf,
+                tline.timeline_id,
+                tline.tenant_shard_id,
+                deltas.first().unwrap().0,
+                gc_cutoff..end_lsn,
+                ctx,
+            )
+            .await?;
+            let key_end = deltas.last().unwrap().0.next();
+            for (key, lsn, val) in deltas {
+                delta_layer_writer.put_value(key, lsn, val, ctx).await?;
+            }
+            let delta_layer = delta_layer_writer.finish(key_end, tline, ctx).await?;
+            Ok(Some(delta_layer))
+        }
+
        let mut image_layer_writer = ImageLayerWriter::new(
            self.conf,
            self.timeline_id,
@@ -1087,6 +1165,10 @@ impl Timeline {
        )
        .await?;

+        let mut delta_values = Vec::new();
+        let delta_split_points = delta_split_points.into_iter().collect_vec();
+        let mut current_delta_split_point = 0;
+        let mut delta_layers = Vec::new();
        for item @ (key, _, _) in &all_key_values {
            if &last_key == key {
                accumulated_values.push(item);
@@ -1094,34 +1176,63 @@ impl Timeline {
                let (deltas, image) =
                    flush_accumulated_states(self, last_key, &accumulated_values, gc_cutoff)
                        .await?;
+                // Put the image into the image layer. Currently we have a single big layer for the compaction.
                image_layer_writer.put_image(last_key, image, ctx).await?;
-                for (key, lsn, val) in deltas {
-                    delta_layer_writer.put_value(key, lsn, val, ctx).await?;
-                }
+                delta_values.extend(deltas);
+                delta_layers.extend(
+                    flush_deltas(
+                        &mut delta_values,
+                        last_key,
+                        &delta_split_points,
+                        &mut current_delta_split_point,
+                        self,
+                        gc_cutoff,
+                        ctx,
+                    )
+                    .await?,
+                );
                accumulated_values.clear();
                accumulated_values.push(item);
                last_key = *key;
            }
        }
+
+        // TODO: move this part to the loop body
        let (deltas, image) =
            flush_accumulated_states(self, last_key, &accumulated_values, gc_cutoff).await?;
+        // Put the image into the image layer. Currently we have a single big layer for the compaction.
        image_layer_writer.put_image(last_key, image, ctx).await?;
-        for (key, lsn, val) in deltas {
-            delta_layer_writer.put_value(key, lsn, val, ctx).await?;
-        }
-        accumulated_values.clear();
-        // TODO: split layers
-        let delta_layer = delta_layer_writer.finish(last_key, self, ctx).await?;
+        delta_values.extend(deltas);
+        delta_layers.extend(
+            flush_deltas(
+                &mut delta_values,
+                last_key,
+                &delta_split_points,
+                &mut current_delta_split_point,
+                self,
+                gc_cutoff,
+                ctx,
+            )
+            .await?,
+        );
+
        let image_layer = image_layer_writer.finish(self, ctx).await?;
+        info!(
+            "produced {} delta layers and {} image layers",
+            delta_layers.len(),
+            1
+        );
+        let mut compact_to = Vec::new();
+        compact_to.extend(delta_layers);
+        compact_to.push(image_layer);
        // Step 3: Place back to the layer map.
        {
            let mut guard = self.layers.write().await;
-            guard.finish_gc_compaction(
-                &layer_selection,
-                &[delta_layer.clone(), image_layer.clone()],
-                &self.metrics,
-            )
+            guard.finish_gc_compaction(&layer_selection, &compact_to, &self.metrics)
        };
+
+        self.remote_client
+            .schedule_compaction_update(&layer_selection, &compact_to)?;
        Ok(())
    }
 }
--- a/pageserver/src/tenant/timeline/delete.rs
+++ b/pageserver/src/tenant/timeline/delete.rs
@@ -255,7 +255,6 @@ impl DeleteTimelineFlow {
    }

    /// Shortcut to create Timeline in stopping state and spawn deletion task.
-    /// See corresponding parts of [`crate::tenant::delete::DeleteTenantFlow`]
    #[instrument(skip_all, fields(%timeline_id))]
    pub async fn resume_deletion(
        tenant: Arc<Tenant>,
@@ -273,6 +272,7 @@ impl DeleteTimelineFlow {
                TimelineResources {
                    remote_client,
                    timeline_get_throttle: tenant.timeline_get_throttle.clone(),
+                    l0_flush_global_state: tenant.l0_flush_global_state.clone(),
                },
                // Important. We dont pass ancestor above because it can be missing.
                // Thus we need to skip the validation here.
@@ -420,10 +420,6 @@ impl DeleteTimelineFlow {
        Ok(())
    }

-    pub(crate) fn is_finished(&self) -> bool {
-        matches!(self, Self::Finished)
-    }
-
    pub(crate) fn is_not_started(&self) -> bool {
        matches!(self, Self::NotStarted)
    }
--- a/pageserver/src/tenant/timeline/layer_manager.rs
+++ b/pageserver/src/tenant/timeline/layer_manager.rs
@@ -227,7 +227,6 @@ impl LayerManager {
    }

    /// Called when a GC-compaction is completed.
-    #[cfg(test)]
    pub(crate) fn finish_gc_compaction(
        &mut self,
        compact_from: &[Layer],
--- a/pageserver/src/tenant/timeline/walreceiver/walreceiver_connection.rs
+++ b/pageserver/src/tenant/timeline/walreceiver/walreceiver_connection.rs
@@ -26,7 +26,7 @@ use tracing::{debug, error, info, trace, warn, Instrument};
 use super::TaskStateUpdate;
 use crate::{
    context::RequestContext,
-    metrics::{LIVE_CONNECTIONS_COUNT, WALRECEIVER_STARTED_CONNECTIONS, WAL_INGEST},
+    metrics::{LIVE_CONNECTIONS, WALRECEIVER_STARTED_CONNECTIONS, WAL_INGEST},
    task_mgr::TaskKind,
    task_mgr::WALRECEIVER_RUNTIME,
    tenant::{debug_assert_current_span_has_tenant_and_timeline_id, Timeline, WalReceiverInfo},
@@ -208,14 +208,9 @@ pub(super) async fn handle_walreceiver_connection(
        .instrument(tracing::info_span!("poller")),
    );

-    // Immediately increment the gauge, then create a job to decrement it on task exit.
-    // One of the pros of `defer!` is that this will *most probably*
-    // get called, even in presence of panics.
-    let gauge = LIVE_CONNECTIONS_COUNT.with_label_values(&["wal_receiver"]);
-    gauge.inc();
-    scopeguard::defer! {
-        gauge.dec();
-    }
+    let _guard = LIVE_CONNECTIONS
+        .with_label_values(&["wal_receiver"])
+        .guard();

    let identify = identify_system(&replication_client).await?;
    info!("{identify:?}");
--- a/pageserver/src/tenant/vectored_blob_io.rs
+++ b/pageserver/src/tenant/vectored_blob_io.rs
@@ -20,6 +20,7 @@ use std::num::NonZeroUsize;

 use bytes::BytesMut;
 use pageserver_api::key::Key;
+use tokio_epoll_uring::BoundedBuf;
 use utils::lsn::Lsn;
 use utils::vec_map::VecMap;

@@ -77,7 +78,7 @@ pub(crate) struct VectoredReadBuilder {
    start: u64,
    end: u64,
    blobs_at: VecMap<u64, BlobMeta>,
-    max_read_size: usize,
+    max_read_size: Option<usize>,
 }

 impl VectoredReadBuilder {
@@ -90,7 +91,7 @@ impl VectoredReadBuilder {
        start_offset: u64,
        end_offset: u64,
        meta: BlobMeta,
-        max_read_size: usize,
+        max_read_size: Option<usize>,
    ) -> Self {
        let mut blobs_at = VecMap::default();
        blobs_at
@@ -111,7 +112,13 @@ impl VectoredReadBuilder {
    pub(crate) fn extend(&mut self, start: u64, end: u64, meta: BlobMeta) -> VectoredReadExtended {
        tracing::trace!(start, end, "trying to extend");
        let size = (end - start) as usize;
-        if self.end == start && self.size() + size <= self.max_read_size {
+        if self.end == start && {
+            if let Some(max_read_size) = self.max_read_size {
+                self.size() + size <= max_read_size
+            } else {
+                true
+            }
+        } {
            self.end = end;
            self.blobs_at
                .append(start, meta)
@@ -157,7 +164,7 @@ pub struct VectoredReadPlanner {
    // Arguments for previous blob passed into [`VectoredReadPlanner::handle`]
    prev: Option<(Key, Lsn, u64, BlobFlag)>,

-    max_read_size: usize,
+    max_read_size: Option<usize>,
 }

 impl VectoredReadPlanner {
@@ -165,7 +172,20 @@ impl VectoredReadPlanner {
        Self {
            blobs: BTreeMap::new(),
            prev: None,
-            max_read_size,
+            max_read_size: Some(max_read_size),
+        }
+    }
+
+    /// This function should *only* be used if the caller has a way to control the limit. e.g., in [`StreamingVectoredReadPlanner`],
+    /// it uses the vectored read planner to avoid duplicated logic on handling blob start/end, while expecting the vectored
+    /// read planner to give a single read to a continuous range of bytes in the image layer. Therefore, it does not need the
+    /// code path to split reads into chunks of `max_read_size`, and controls the read size itself.
+    #[cfg(test)]
+    pub(crate) fn new_caller_controlled_max_limit() -> Self {
+        Self {
+            blobs: BTreeMap::new(),
+            prev: None,
+            max_read_size: None,
        }
    }

@@ -297,8 +317,9 @@ impl<'a> VectoredBlobReader<'a> {
        );
        let buf = self
            .file
-            .read_exact_at_n(buf, read.start, read.size(), ctx)
-            .await?;
+            .read_exact_at(buf.slice(0..read.size()), read.start, ctx)
+            .await?
+            .into_inner();

        let blobs_at = read.blobs_at.as_slice();
        let start_offset = blobs_at.first().expect("VectoredRead is never empty").0;
@@ -354,6 +375,87 @@ impl<'a> VectoredBlobReader<'a> {
    }
 }

+/// Read planner used in [`crate::tenant::storage_layer::image_layer::ImageLayerIterator`]. It provides a streaming API for
+/// getting read blobs. It returns a batch when `handle` gets called and when the current key would exceed the read_size and
+/// max_cnt constraints. Underlying it uses [`VectoredReadPlanner`].
+#[cfg(test)]
+pub struct StreamingVectoredReadPlanner {
+    planner: VectoredReadPlanner,
+    /// Max read size per batch
+    max_read_size: u64,
+    /// Max item count per batch
+    max_cnt: usize,
+    /// The first offset of this batch
+    this_batch_first_offset: Option<u64>,
+    /// Size of the current batch
+    cnt: usize,
+}
+
+#[cfg(test)]
+impl StreamingVectoredReadPlanner {
+    pub fn new(max_read_size: u64, max_cnt: usize) -> Self {
+        assert!(max_cnt > 0);
+        assert!(max_read_size > 0);
+        Self {
+            // We want to have exactly one read syscall (plus several others for index lookup) for each `next_batch` call.
+            // Therefore, we enforce `self.max_read_size` by ourselves instead of using the VectoredReadPlanner's capability,
+            // to avoid splitting into two I/Os.
+            planner: VectoredReadPlanner::new_caller_controlled_max_limit(),
+            max_cnt,
+            max_read_size,
+            this_batch_first_offset: None,
+            cnt: 0,
+        }
+    }
+
+    fn emit(&mut self, this_batch_first_offset: u64) -> VectoredRead {
+        let planner = std::mem::replace(
+            &mut self.planner,
+            VectoredReadPlanner::new_caller_controlled_max_limit(),
+        );
+        self.this_batch_first_offset = Some(this_batch_first_offset);
+        self.cnt = 1;
+        let mut batch = planner.finish();
+        assert_eq!(batch.len(), 1, "should have exactly one read batch");
+        batch.pop().unwrap()
+    }
+
+    pub fn handle(
+        &mut self,
+        key: Key,
+        lsn: Lsn,
+        offset: u64,
+        flag: BlobFlag,
+    ) -> Option<VectoredRead> {
+        if let Some(begin_offset) = self.this_batch_first_offset {
+            // Each batch will have at least one item b/c `self.this_batch_first_offset` is set
+            // after one item gets processed
+            if offset - begin_offset > self.max_read_size {
+                self.planner.handle_range_end(offset); // End the current batch with the offset
+                let batch = self.emit(offset); // Produce a batch
+                self.planner.handle(key, lsn, offset, flag); // Add this key to the next batch
+                return Some(batch);
+            }
+        } else {
+            self.this_batch_first_offset = Some(offset)
+        }
+        if self.cnt >= self.max_cnt {
+            self.planner.handle_range_end(offset); // End the current batch with the offset
+            let batch = self.emit(offset); // Produce a batch
+            self.planner.handle(key, lsn, offset, flag); // Add this key to the next batch
+            return Some(batch);
+        }
+        self.planner.handle(key, lsn, offset, flag); // Add this key to the current batch
+        self.cnt += 1;
+        None
+    }
+
+    pub fn handle_range_end(&mut self, offset: u64) -> VectoredRead {
+        self.planner.handle_range_end(offset);
+        self.emit(offset)
+    }
+}
+
 #[cfg(test)]
 mod tests {
    use super::*;
--- a/pageserver/src/virtual_file.rs
+++ b/pageserver/src/virtual_file.rs
@@ -13,7 +13,7 @@
 use crate::context::RequestContext;
 use crate::metrics::{StorageIoOperation, STORAGE_IO_SIZE, STORAGE_IO_TIME_METRIC};

-use crate::page_cache::PageWriteGuard;
+use crate::page_cache::{PageWriteGuard, PAGE_SZ};
 use crate::tenant::TENANTS_SEGMENT_NAME;
 use camino::{Utf8Path, Utf8PathBuf};
 use once_cell::sync::OnceCell;
@@ -48,6 +48,7 @@ pub(crate) mod owned_buffers_io {
    //! but for the time being we're proving out the primitives in the neon.git repo
    //! for faster iteration.

+    pub(crate) mod slice;
    pub(crate) mod write;
    pub(crate) mod util {
        pub(crate) mod size_tracking_writer;
@@ -143,16 +144,17 @@ struct SlotInner {
 /// Impl of [`tokio_epoll_uring::IoBuf`] and [`tokio_epoll_uring::IoBufMut`] for [`PageWriteGuard`].
 struct PageWriteGuardBuf {
    page: PageWriteGuard<'static>,
-    init_up_to: usize,
 }
 // Safety: the [`PageWriteGuard`] gives us exclusive ownership of the page cache slot,
 // and the location remains stable even if [`Self`] or the [`PageWriteGuard`] is moved.
+// Page cache pages are zero-initialized, so, wrt uninitialized memory we're good.
+// (Page cache tracks separately whether the contents are valid, see `PageWriteGuard::mark_valid`.)
 unsafe impl tokio_epoll_uring::IoBuf for PageWriteGuardBuf {
    fn stable_ptr(&self) -> *const u8 {
        self.page.as_ptr()
    }
    fn bytes_init(&self) -> usize {
-        self.init_up_to
+        self.page.len()
    }
    fn bytes_total(&self) -> usize {
        self.page.len()
@@ -166,8 +168,8 @@ unsafe impl tokio_epoll_uring::IoBufMut for PageWriteGuardBuf {
    }

    unsafe fn set_init(&mut self, pos: usize) {
+        // There shouldn't really be any reason to call this API since bytes_init() == bytes_total().
        assert!(pos <= self.page.len());
-        self.init_up_to = pos;
    }
 }

@@ -585,37 +587,37 @@ impl VirtualFile {
        Ok(self.pos)
    }

-    pub async fn read_exact_at<B>(
+    /// Read the file contents in range `offset..(offset + slice.bytes_total())` into `slice[0..slice.bytes_total()]`.
+    ///
+    /// The returned `Slice<Buf>` is equivalent to the input `slice`, i.e., it's the same view into the same buffer.
+    pub async fn read_exact_at<Buf>(
        &self,
-        buf: B,
+        slice: Slice<Buf>,
        offset: u64,
        ctx: &RequestContext,
-    ) -> Result<B, Error>
+    ) -> Result<Slice<Buf>, Error>
    where
-        B: IoBufMut + Send,
+        Buf: IoBufMut + Send,
    {
-        let (buf, res) = read_exact_at_impl(buf, offset, None, |buf, offset| {
-            self.read_at(buf, offset, ctx)
-        })
-        .await;
-        res.map(|()| buf)
-    }
+        let assert_we_return_original_bounds = if cfg!(debug_assertions) {
+            Some((slice.stable_ptr() as usize, slice.bytes_total()))
+        } else {
+            None
+        };

-    pub async fn read_exact_at_n<B>(
-        &self,
-        buf: B,
-        offset: u64,
-        count: usize,
-        ctx: &RequestContext,
-    ) -> Result<B, Error>
-    where
-        B: IoBufMut + Send,
-    {
-        let (buf, res) = read_exact_at_impl(buf, offset, Some(count), |buf, offset| {
-            self.read_at(buf, offset, ctx)
-        })
-        .await;
-        res.map(|()| buf)
+        let original_bounds = slice.bounds();
+        let (buf, res) =
+            read_exact_at_impl(slice, offset, |buf, offset| self.read_at(buf, offset, ctx)).await;
+        let res = res.map(|_| buf.slice(original_bounds));
+
+        if let Some(original_bounds) = assert_we_return_original_bounds {
+            if let Ok(slice) = &res {
+                let returned_bounds = (slice.stable_ptr() as usize, slice.bytes_total());
+                assert_eq!(original_bounds, returned_bounds);
+            }
+        }
+
+        res
    }

    /// Like [`Self::read_exact_at`] but for [`PageWriteGuard`].
@@ -625,13 +627,11 @@ impl VirtualFile {
        offset: u64,
        ctx: &RequestContext,
    ) -> Result<PageWriteGuard<'static>, Error> {
-        let buf = PageWriteGuardBuf {
-            page,
-            init_up_to: 0,
-        };
-        let res = self.read_exact_at(buf, offset, ctx).await;
-        res.map(|PageWriteGuardBuf { page, .. }| page)
-            .map_err(|e| Error::new(ErrorKind::Other, e))
+        let buf = PageWriteGuardBuf { page }.slice_full();
+        debug_assert_eq!(buf.bytes_total(), PAGE_SZ);
+        self.read_exact_at(buf, offset, ctx)
+            .await
+            .map(|slice| slice.into_inner().page)
    }

    // Copied from https://doc.rust-lang.org/1.72.0/src/std/os/unix/fs.rs.html#219-235
@@ -722,14 +722,14 @@ impl VirtualFile {
        (buf, Ok(n))
    }

-    pub(crate) async fn read_at<B>(
+    pub(crate) async fn read_at<Buf>(
        &self,
-        buf: B,
+        buf: tokio_epoll_uring::Slice<Buf>,
        offset: u64,
        _ctx: &RequestContext, /* TODO: use for metrics: https://github.com/neondatabase/neon/issues/6107 */
-    ) -> (B, Result<usize, Error>)
+    ) -> (tokio_epoll_uring::Slice<Buf>, Result<usize, Error>)
    where
-        B: tokio_epoll_uring::BoundedBufMut + Send,
+        Buf: tokio_epoll_uring::IoBufMut + Send,
    {
        let file_guard = match self.lock_file().await {
            Ok(file_guard) => file_guard,
@@ -781,26 +781,16 @@ impl VirtualFile {
 }

 // Adapted from https://doc.rust-lang.org/1.72.0/src/std/os/unix/fs.rs.html#117-135
-pub async fn read_exact_at_impl<B, F, Fut>(
-    buf: B,
+pub async fn read_exact_at_impl<Buf, F, Fut>(
+    mut buf: tokio_epoll_uring::Slice<Buf>,
    mut offset: u64,
-    count: Option<usize>,
    mut read_at: F,
-) -> (B, std::io::Result<()>)
+) -> (Buf, std::io::Result<()>)
 where
-    B: IoBufMut + Send,
-    F: FnMut(tokio_epoll_uring::Slice<B>, u64) -> Fut,
-    Fut: std::future::Future<Output = (tokio_epoll_uring::Slice<B>, std::io::Result<usize>)>,
+    Buf: IoBufMut + Send,
+    F: FnMut(tokio_epoll_uring::Slice<Buf>, u64) -> Fut,
+    Fut: std::future::Future<Output = (tokio_epoll_uring::Slice<Buf>, std::io::Result<usize>)>,
 {
-    let mut buf: tokio_epoll_uring::Slice<B> = match count {
-        Some(count) => {
-            assert!(count <= buf.bytes_total());
-            assert!(count > 0);
-            buf.slice(..count) // may include uninitialized memory
-        }
-        None => buf.slice_full(), // includes all the uninitialized memory
-    };
-
    while buf.bytes_total() != 0 {
        let res;
        (buf, res) = read_at(buf, offset).await;
@@ -882,7 +872,7 @@ mod test_read_exact_at_impl {

    #[tokio::test]
    async fn test_basic() {
-        let buf = Vec::with_capacity(5);
+        let buf = Vec::with_capacity(5).slice_full();
        let mock_read_at = Arc::new(tokio::sync::Mutex::new(MockReadAt {
            expectations: VecDeque::from(vec![Expectation {
                offset: 0,
@@ -890,7 +880,7 @@ mod test_read_exact_at_impl {
                result: Ok(vec![b'a', b'b', b'c', b'd', b'e']),
            }]),
        }));
-        let (buf, res) = read_exact_at_impl(buf, 0, None, |buf, offset| {
+        let (buf, res) = read_exact_at_impl(buf, 0, |buf, offset| {
            let mock_read_at = Arc::clone(&mock_read_at);
            async move { mock_read_at.lock().await.read_at(buf, offset).await }
        })
@@ -899,33 +889,13 @@ mod test_read_exact_at_impl {
        assert_eq!(buf, vec![b'a', b'b', b'c', b'd', b'e']);
    }

-    #[tokio::test]
-    async fn test_with_count() {
-        let buf = Vec::with_capacity(5);
-        let mock_read_at = Arc::new(tokio::sync::Mutex::new(MockReadAt {
-            expectations: VecDeque::from(vec![Expectation {
-                offset: 0,
-                bytes_total: 3,
-                result: Ok(vec![b'a', b'b', b'c']),
-            }]),
-        }));
-
-        let (buf, res) = read_exact_at_impl(buf, 0, Some(3), |buf, offset| {
-            let mock_read_at = Arc::clone(&mock_read_at);
-            async move { mock_read_at.lock().await.read_at(buf, offset).await }
-        })
-        .await;
-        assert!(res.is_ok());
-        assert_eq!(buf, vec![b'a', b'b', b'c']);
-    }
-
    #[tokio::test]
    async fn test_empty_buf_issues_no_syscall() {
-        let buf = Vec::new();
+        let buf = Vec::new().slice_full();
        let mock_read_at = Arc::new(tokio::sync::Mutex::new(MockReadAt {
            expectations: VecDeque::new(),
        }));
-        let (_buf, res) = read_exact_at_impl(buf, 0, None, |buf, offset| {
+        let (_buf, res) = read_exact_at_impl(buf, 0, |buf, offset| {
            let mock_read_at = Arc::clone(&mock_read_at);
            async move { mock_read_at.lock().await.read_at(buf, offset).await }
        })
@@ -935,7 +905,7 @@ mod test_read_exact_at_impl {

    #[tokio::test]
    async fn test_two_read_at_calls_needed_until_buf_filled() {
-        let buf = Vec::with_capacity(4);
+        let buf = Vec::with_capacity(4).slice_full();
        let mock_read_at = Arc::new(tokio::sync::Mutex::new(MockReadAt {
            expectations: VecDeque::from(vec![
                Expectation {
@@ -950,7 +920,7 @@ mod test_read_exact_at_impl {
                },
            ]),
        }));
-        let (buf, res) = read_exact_at_impl(buf, 0, None, |buf, offset| {
+        let (buf, res) = read_exact_at_impl(buf, 0, |buf, offset| {
            let mock_read_at = Arc::clone(&mock_read_at);
            async move { mock_read_at.lock().await.read_at(buf, offset).await }
        })
@@ -961,7 +931,7 @@ mod test_read_exact_at_impl {

    #[tokio::test]
    async fn test_eof_before_buffer_full() {
-        let buf = Vec::with_capacity(3);
+        let buf = Vec::with_capacity(3).slice_full();
        let mock_read_at = Arc::new(tokio::sync::Mutex::new(MockReadAt {
            expectations: VecDeque::from(vec![
                Expectation {
@@ -981,7 +951,7 @@ mod test_read_exact_at_impl {
                },
            ]),
        }));
-        let (_buf, res) = read_exact_at_impl(buf, 0, None, |buf, offset| {
+        let (_buf, res) = read_exact_at_impl(buf, 0, |buf, offset| {
            let mock_read_at = Arc::clone(&mock_read_at);
            async move { mock_read_at.lock().await.read_at(buf, offset).await }
        })
@@ -1051,27 +1021,29 @@ impl VirtualFile {
        ctx: &RequestContext,
    ) -> Result<crate::tenant::block_io::BlockLease<'_>, std::io::Error> {
        use crate::page_cache::PAGE_SZ;
-        let buf = vec![0; PAGE_SZ];
-        let buf = self
-            .read_exact_at(buf, blknum as u64 * (PAGE_SZ as u64), ctx)
+        let slice = Vec::with_capacity(PAGE_SZ).slice_full();
+        assert_eq!(slice.bytes_total(), PAGE_SZ);
+        let slice = self
+            .read_exact_at(slice, blknum as u64 * (PAGE_SZ as u64), ctx)
            .await?;
-        Ok(crate::tenant::block_io::BlockLease::Vec(buf))
+        Ok(crate::tenant::block_io::BlockLease::Vec(slice.into_inner()))
    }

    async fn read_to_end(&mut self, buf: &mut Vec<u8>, ctx: &RequestContext) -> Result<(), Error> {
        let mut tmp = vec![0; 128];
        loop {
-            let res;
-            (tmp, res) = self.read_at(tmp, self.pos, ctx).await;
+            let slice = tmp.slice(..128);
+            let (slice, res) = self.read_at(slice, self.pos, ctx).await;
            match res {
                Ok(0) => return Ok(()),
                Ok(n) => {
                    self.pos += n as u64;
-                    buf.extend_from_slice(&tmp[..n]);
+                    buf.extend_from_slice(&slice[..n]);
                }
                Err(ref e) if e.kind() == std::io::ErrorKind::Interrupted => {}
                Err(e) => return Err(e),
            }
+            tmp = slice.into_inner();
        }
    }
 }
@@ -1185,6 +1157,7 @@ mod tests {
    use crate::task_mgr::TaskKind;

    use super::*;
+    use owned_buffers_io::slice::SliceExt;
    use rand::seq::SliceRandom;
    use rand::thread_rng;
    use rand::Rng;
@@ -1206,13 +1179,16 @@ mod tests {
    impl MaybeVirtualFile {
        async fn read_exact_at(
            &self,
-            mut buf: Vec<u8>,
+            mut slice: tokio_epoll_uring::Slice<Vec<u8>>,
            offset: u64,
            ctx: &RequestContext,
-        ) -> Result<Vec<u8>, Error> {
+        ) -> Result<tokio_epoll_uring::Slice<Vec<u8>>, Error> {
            match self {
-                MaybeVirtualFile::VirtualFile(file) => file.read_exact_at(buf, offset, ctx).await,
-                MaybeVirtualFile::File(file) => file.read_exact_at(&mut buf, offset).map(|()| buf),
+                MaybeVirtualFile::VirtualFile(file) => file.read_exact_at(slice, offset, ctx).await,
+                MaybeVirtualFile::File(file) => {
+                    let rust_slice: &mut [u8] = slice.as_mut_rust_slice_full_zeroed();
+                    file.read_exact_at(rust_slice, offset).map(|()| slice)
+                }
            }
        }
        async fn write_all_at<B: BoundedBuf<Buf = Buf>, Buf: IoBuf + Send>(
@@ -1286,9 +1262,12 @@ mod tests {
            len: usize,
            ctx: &RequestContext,
        ) -> Result<String, Error> {
-            let buf = vec![0; len];
-            let buf = self.read_exact_at(buf, pos, ctx).await?;
-            Ok(String::from_utf8(buf).unwrap())
+            let slice = Vec::with_capacity(len).slice_full();
+            assert_eq!(slice.bytes_total(), len);
+            let slice = self.read_exact_at(slice, pos, ctx).await?;
+            let vec = slice.into_inner();
+            assert_eq!(vec.len(), len);
+            Ok(String::from_utf8(vec).unwrap())
        }
    }

@@ -1507,7 +1486,11 @@ mod tests {
                let mut rng = rand::rngs::OsRng;
                for _ in 1..1000 {
                    let f = &files[rng.gen_range(0..files.len())];
-                    buf = f.read_exact_at(buf, 0, &ctx).await.unwrap();
+                    buf = f
+                        .read_exact_at(buf.slice_full(), 0, &ctx)
+                        .await
+                        .unwrap()
+                        .into_inner();
                    assert!(buf == SAMPLE);
                }
            });
--- a/pageserver/src/virtual_file/io_engine.rs
+++ b/pageserver/src/virtual_file/io_engine.rs
@@ -107,7 +107,7 @@ use std::{
    sync::atomic::{AtomicU8, Ordering},
 };

-use super::{FileGuard, Metadata};
+use super::{owned_buffers_io::slice::SliceExt, FileGuard, Metadata};

 #[cfg(target_os = "linux")]
 fn epoll_uring_error_to_std(e: tokio_epoll_uring::Error<std::io::Error>) -> std::io::Error {
@@ -120,38 +120,29 @@ fn epoll_uring_error_to_std(e: tokio_epoll_uring::Error<std::io::Error>) -> std:
 }

 impl IoEngine {
-    pub(super) async fn read_at<B>(
+    pub(super) async fn read_at<Buf>(
        &self,
        file_guard: FileGuard,
        offset: u64,
-        mut buf: B,
-    ) -> ((FileGuard, B), std::io::Result<usize>)
+        mut slice: tokio_epoll_uring::Slice<Buf>,
+    ) -> (
+        (FileGuard, tokio_epoll_uring::Slice<Buf>),
+        std::io::Result<usize>,
+    )
    where
-        B: tokio_epoll_uring::BoundedBufMut + Send,
+        Buf: tokio_epoll_uring::IoBufMut + Send,
    {
        match self {
            IoEngine::NotSet => panic!("not initialized"),
            IoEngine::StdFs => {
-                // SAFETY: `dst` only lives at most as long as this match arm, during which buf remains valid memory.
-                let dst = unsafe {
-                    std::slice::from_raw_parts_mut(buf.stable_mut_ptr(), buf.bytes_total())
-                };
-                let res = file_guard.with_std_file(|std_file| std_file.read_at(dst, offset));
-                if let Ok(nbytes) = &res {
-                    assert!(*nbytes <= buf.bytes_total());
-                    // SAFETY: see above assertion
-                    unsafe {
-                        buf.set_init(*nbytes);
-                    }
-                }
-                #[allow(dropping_references)]
-                drop(dst);
-                ((file_guard, buf), res)
+                let rust_slice = slice.as_mut_rust_slice_full_zeroed();
+                let res = file_guard.with_std_file(|std_file| std_file.read_at(rust_slice, offset));
+                ((file_guard, slice), res)
            }
            #[cfg(target_os = "linux")]
            IoEngine::TokioEpollUring => {
                let system = tokio_epoll_uring_ext::thread_local_system().await;
-                let (resources, res) = system.read(file_guard, offset, buf).await;
+                let (resources, res) = system.read(file_guard, offset, slice).await;
                (resources, res.map_err(epoll_uring_error_to_std))
            }
        }
--- a/pageserver/src/virtual_file/owned_buffers_io/slice.rs
+++ b/pageserver/src/virtual_file/owned_buffers_io/slice.rs
@@ -0,0 +1,121 @@
+use tokio_epoll_uring::BoundedBuf;
+use tokio_epoll_uring::BoundedBufMut;
+use tokio_epoll_uring::IoBufMut;
+use tokio_epoll_uring::Slice;
+
+pub(crate) trait SliceExt {
+    /// Get a `&mut[0..self.bytes_total()`] slice, for when you need to do borrow-based IO.
+    ///
+    /// See the test case `test_slice_full_zeroed` for the difference to just doing `&slice[..]`
+    fn as_mut_rust_slice_full_zeroed(&mut self) -> &mut [u8];
+}
+
+impl<B> SliceExt for Slice<B>
+where
+    B: IoBufMut,
+{
+    #[inline(always)]
+    fn as_mut_rust_slice_full_zeroed(&mut self) -> &mut [u8] {
+        // zero-initialize the uninitialized parts of the buffer so we can create a Rust slice
+        //
+        // SAFETY: we own `slice`, don't write outside the bounds
+        unsafe {
+            let to_init = self.bytes_total() - self.bytes_init();
+            self.stable_mut_ptr()
+                .add(self.bytes_init())
+                .write_bytes(0, to_init);
+            self.set_init(self.bytes_total());
+        };
+        let bytes_total = self.bytes_total();
+        &mut self[0..bytes_total]
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use std::io::Read;
+
+    use super::*;
+    use bytes::Buf;
+    use tokio_epoll_uring::Slice;
+
+    #[test]
+    fn test_slice_full_zeroed() {
+        let make_fake_file = || bytes::BytesMut::from(&b"12345"[..]).reader();
+
+        // before we start the test, let's make sure we have a shared understanding of what slice_full does
+        {
+            let buf = Vec::with_capacity(3);
+            let slice: Slice<_> = buf.slice_full();
+            assert_eq!(slice.bytes_init(), 0);
+            assert_eq!(slice.bytes_total(), 3);
+            let rust_slice = &slice[..];
+            assert_eq!(
+                rust_slice.len(),
+                0,
+                "Slice only derefs to a &[u8] of the initialized part"
+            );
+        }
+
+        // and also let's establish a shared understanding of .slice()
+        {
+            let buf = Vec::with_capacity(3);
+            let slice: Slice<_> = buf.slice(0..2);
+            assert_eq!(slice.bytes_init(), 0);
+            assert_eq!(slice.bytes_total(), 2);
+            let rust_slice = &slice[..];
+            assert_eq!(
+                rust_slice.len(),
+                0,
+                "Slice only derefs to a &[u8] of the initialized part"
+            );
+        }
+
+        // the above leads to the easy mistake of using slice[..] for borrow-based IO like so:
+        {
+            let buf = Vec::with_capacity(3);
+            let mut slice: Slice<_> = buf.slice_full();
+            assert_eq!(slice[..].len(), 0);
+            let mut file = make_fake_file();
+            file.read_exact(&mut slice[..]).unwrap(); // one might think this reads 3 bytes but it reads 0
+            assert_eq!(&slice[..] as &[u8], &[][..] as &[u8]);
+        }
+
+        // With owned buffers IO like with VirtualFilem, you could totally
+        // pass in a `Slice` with bytes_init()=0 but bytes_total()=5
+        // and it will read 5 bytes into the slice, and return a slice that has bytes_init()=5.
+        {
+            // TODO: demo
+        }
+
+        //
+        // Ok, now that we have a shared understanding let's demo how to use the extension trait.
+        //
+
+        // slice_full()
+        {
+            let buf = Vec::with_capacity(3);
+            let mut slice: Slice<_> = buf.slice_full();
+            let rust_slice = slice.as_mut_rust_slice_full_zeroed();
+            assert_eq!(rust_slice.len(), 3);
+            assert_eq!(rust_slice, &[0, 0, 0]);
+            let mut file = make_fake_file();
+            file.read_exact(rust_slice).unwrap();
+            assert_eq!(rust_slice, b"123");
+            assert_eq!(&slice[..], b"123");
+        }
+
+        // .slice(..)
+        {
+            let buf = Vec::with_capacity(3);
+            let mut slice: Slice<_> = buf.slice(0..2);
+            let rust_slice = slice.as_mut_rust_slice_full_zeroed();
+            assert_eq!(rust_slice.len(), 2);
+            assert_eq!(rust_slice, &[0, 0]);
+            let mut file = make_fake_file();
+            file.read_exact(rust_slice).unwrap();
+            assert_eq!(rust_slice, b"12");
+            assert_eq!(&slice[..], b"12");
+        }
+    }
+}
--- a/pageserver/src/walingest.rs
+++ b/pageserver/src/walingest.rs
@@ -1384,14 +1384,31 @@ impl WalIngest {
            // Note: The multixact members can wrap around, even within one WAL record.
            offset = offset.wrapping_add(n_this_page as u32);
        }
-        if xlrec.mid >= self.checkpoint.nextMulti {
-            self.checkpoint.nextMulti = xlrec.mid + 1;
-            self.checkpoint_modified = true;
-        }
-        if xlrec.moff + xlrec.nmembers > self.checkpoint.nextMultiOffset {
-            self.checkpoint.nextMultiOffset = xlrec.moff + xlrec.nmembers;
+        let next_offset = offset;
+        assert!(xlrec.moff.wrapping_add(xlrec.nmembers) == next_offset);
+
+        // Update next-multi-xid and next-offset
+        //
+        // NB: In PostgreSQL, the next-multi-xid stored in the control file is allowed to
+        // go to 0, and it's fixed up by skipping to FirstMultiXactId in functions that
+        // read it, like GetNewMultiXactId(). This is different from how nextXid is
+        // incremented! nextXid skips over < FirstNormalTransactionId when the the value
+        // is stored, so it's never 0 in a checkpoint.
+        //
+        // I don't know why it's done that way, it seems less error-prone to skip over 0
+        // when the value is stored rather than when it's read. But let's do it the same
+        // way here.
+        let next_multi_xid = xlrec.mid.wrapping_add(1);
+
+        if self
+            .checkpoint
+            .update_next_multixid(next_multi_xid, next_offset)
+        {
            self.checkpoint_modified = true;
        }
+
+        // Also update the next-xid with the highest member. According to the comments in
+        // multixact_redo(), this shouldn't be necessary, but let's do the same here.
        let max_mbr_xid = xlrec.members.iter().fold(None, |acc, mbr| {
            if let Some(max_xid) = acc {
                if mbr.xid.wrapping_sub(max_xid) as i32 > 0 {
--- a/pageserver/src/walredo.rs
+++ b/pageserver/src/walredo.rs
@@ -40,6 +40,7 @@ use std::time::Duration;
 use std::time::Instant;
 use tracing::*;
 use utils::lsn::Lsn;
+use utils::sync::gate::GateError;
 use utils::sync::heavier_once_cell;

 ///
@@ -53,10 +54,18 @@ pub struct PostgresRedoManager {
    tenant_shard_id: TenantShardId,
    conf: &'static PageServerConf,
    last_redo_at: std::sync::Mutex<Option<Instant>>,
-    /// The current [`process::WalRedoProcess`] that is used by new redo requests.
-    /// We use [`heavier_once_cell`] for coalescing the spawning, but the redo
-    /// requests don't use the [`heavier_once_cell::Guard`] to keep ahold of the
+    /// We use [`heavier_once_cell`] for
+    ///
+    /// 1. coalescing the lazy spawning of walredo processes ([`ProcessOnceCell::Spawned`])
+    /// 2. prevent new processes from being spawned on [`Self::shutdown`] (=> [`ProcessOnceCell::ManagerShutDown`]).
+    ///
+    /// # Spawning
+    ///
+    /// Redo requests use the once cell to coalesce onto one call to [`process::WalRedoProcess::launch`].
+    ///
+    /// Notably, requests don't use the [`heavier_once_cell::Guard`] to keep ahold of the
    /// their process object; we use [`Arc::clone`] for that.
+    ///
    /// This is primarily because earlier implementations that didn't  use [`heavier_once_cell`]
    /// had that behavior; it's probably unnecessary.
    /// The only merit of it is that if one walredo process encounters an error,
@@ -65,7 +74,63 @@ pub struct PostgresRedoManager {
    /// still be using the old redo process. But, those other tasks will most likely
    /// encounter an error as well, and errors are an unexpected condition anyway.
    /// So, probably we could get rid of the `Arc` in the future.
-    redo_process: heavier_once_cell::OnceCell<Arc<process::WalRedoProcess>>,
+    ///
+    /// # Shutdown
+    ///
+    /// See [`Self::launched_processes`].
+    redo_process: heavier_once_cell::OnceCell<ProcessOnceCell>,
+
+    /// Gate that is entered when launching a walredo process and held open
+    /// until the process has been `kill()`ed and `wait()`ed upon.
+    ///
+    /// Manager shutdown waits for this gate to close after setting the
+    /// [`ProcessOnceCell::ManagerShutDown`] state in [`Self::redo_process`].
+    ///
+    /// This type of usage is a bit unusual because gates usually keep track of
+    /// concurrent operations, e.g., every [`Self::request_redo`] that is inflight.
+    /// But we use it here to keep track of the _processes_ that we have launched,
+    /// which may outlive any individual redo request because
+    /// - we keep walredo process around until its quiesced to amortize spawn cost and
+    /// - the Arc may be held by multiple concurrent redo requests, so, just because
+    ///   you replace the [`Self::redo_process`] cell's content doesn't mean the
+    ///   process gets killed immediately.
+    ///
+    /// We could simplify this by getting rid of the [`Arc`].
+    /// See the comment on [`Self::redo_process`] for more details.
+    launched_processes: utils::sync::gate::Gate,
+}
+
+/// See [`PostgresRedoManager::redo_process`].
+enum ProcessOnceCell {
+    Spawned(Arc<Process>),
+    ManagerShutDown,
+}
+
+struct Process {
+    _launched_processes_guard: utils::sync::gate::GateGuard,
+    process: process::WalRedoProcess,
+}
+
+impl std::ops::Deref for Process {
+    type Target = process::WalRedoProcess;
+
+    fn deref(&self) -> &Self::Target {
+        &self.process
+    }
+}
+
+#[derive(Debug, thiserror::Error)]
+pub enum Error {
+    #[error("cancelled")]
+    Cancelled,
+    #[error(transparent)]
+    Other(#[from] anyhow::Error),
+}
+
+macro_rules! bail {
+    ($($arg:tt)*) => {
+        return Err($crate::walredo::Error::Other(::anyhow::anyhow!($($arg)*)));
+    }
 }

 ///
@@ -88,9 +153,9 @@ impl PostgresRedoManager {
        base_img: Option<(Lsn, Bytes)>,
        records: Vec<(Lsn, NeonWalRecord)>,
        pg_version: u32,
-    ) -> anyhow::Result<Bytes> {
+    ) -> Result<Bytes, Error> {
        if records.is_empty() {
-            anyhow::bail!("invalid WAL redo request with no records");
+            bail!("invalid WAL redo request with no records");
        }

        let base_img_lsn = base_img.as_ref().map(|p| p.0).unwrap_or(Lsn::INVALID);
@@ -148,10 +213,10 @@ impl PostgresRedoManager {
                    chrono::Utc::now().checked_sub_signed(chrono::Duration::from_std(age).ok()?)
                })
            },
-            process: self
-                .redo_process
-                .get()
-                .map(|p| WalRedoManagerProcessStatus { pid: p.id() }),
+            process: self.redo_process.get().and_then(|p| match &*p {
+                ProcessOnceCell::Spawned(p) => Some(WalRedoManagerProcessStatus { pid: p.id() }),
+                ProcessOnceCell::ManagerShutDown => None,
+            }),
        }
    }
 }
@@ -170,9 +235,39 @@ impl PostgresRedoManager {
            conf,
            last_redo_at: std::sync::Mutex::default(),
            redo_process: heavier_once_cell::OnceCell::default(),
+            launched_processes: utils::sync::gate::Gate::default(),
        }
    }

+    /// Shut down the WAL redo manager.
+    ///
+    /// After this future completes
+    /// - no redo process is running
+    /// - no new redo process will be spawned
+    /// - redo requests that need walredo process will fail with [`Error::Cancelled`]
+    /// - [`apply_neon`]-only redo requests may still work, but this may change in the future
+    ///
+    /// # Cancel-Safety
+    ///
+    /// This method is cancellation-safe.
+    pub async fn shutdown(&self) {
+        // prevent new processes from being spawned
+        let permit = match self.redo_process.get_or_init_detached().await {
+            Ok(guard) => {
+                let (proc, permit) = guard.take_and_deinit();
+                drop(proc); // this just drops the Arc, its refcount may not be zero yet
+                permit
+            }
+            Err(permit) => permit,
+        };
+        self.redo_process
+            .set(ProcessOnceCell::ManagerShutDown, permit);
+        // wait for ongoing requests to drain and the refcounts of all Arc<WalRedoProcess> that
+        // we ever launched to drop to zero, which when it happens synchronously kill()s & wait()s
+        // for the underlying process.
+        self.launched_processes.close().await;
+    }
+
    /// This type doesn't have its own background task to check for idleness: we
    /// rely on our owner calling this function periodically in its own housekeeping
    /// loops.
@@ -203,38 +298,48 @@ impl PostgresRedoManager {
        records: &[(Lsn, NeonWalRecord)],
        wal_redo_timeout: Duration,
        pg_version: u32,
-    ) -> anyhow::Result<Bytes> {
+    ) -> Result<Bytes, Error> {
        *(self.last_redo_at.lock().unwrap()) = Some(Instant::now());

        let (rel, blknum) = key.to_rel_block().context("invalid record")?;
        const MAX_RETRY_ATTEMPTS: u32 = 1;
        let mut n_attempts = 0u32;
        loop {
-            let proc: Arc<process::WalRedoProcess> =
-                match self.redo_process.get_or_init_detached().await {
-                    Ok(guard) => Arc::clone(&guard),
-                    Err(permit) => {
-                        // don't hold poison_guard, the launch code can bail
-                        let start = Instant::now();
-                        let proc = Arc::new(
-                            process::WalRedoProcess::launch(
+            let proc: Arc<Process> = match self.redo_process.get_or_init_detached().await {
+                Ok(guard) => match &*guard {
+                    ProcessOnceCell::Spawned(proc) => Arc::clone(proc),
+                    ProcessOnceCell::ManagerShutDown => {
+                        return Err(Error::Cancelled);
+                    }
+                },
+                Err(permit) => {
+                    let start = Instant::now();
+                    let proc = Arc::new(Process {
+                            _launched_processes_guard: match self.launched_processes.enter() {
+                                Ok(guard) => guard,
+                                Err(GateError::GateClosed) => unreachable!(
+                                    "shutdown sets the once cell to `ManagerShutDown` state before closing the gate"
+                                ),
+                            },
+                            process: process::WalRedoProcess::launch(
                                self.conf,
                                self.tenant_shard_id,
                                pg_version,
                            )
                            .context("launch walredo process")?,
-                        );
-                        let duration = start.elapsed();
-                        WAL_REDO_PROCESS_LAUNCH_DURATION_HISTOGRAM.observe(duration.as_secs_f64());
-                        info!(
-                            duration_ms = duration.as_millis(),
-                            pid = proc.id(),
-                            "launched walredo process"
-                        );
-                        self.redo_process.set(Arc::clone(&proc), permit);
-                        proc
-                    }
-                };
+                        });
+                    let duration = start.elapsed();
+                    WAL_REDO_PROCESS_LAUNCH_DURATION_HISTOGRAM.observe(duration.as_secs_f64());
+                    info!(
+                        duration_ms = duration.as_millis(),
+                        pid = proc.id(),
+                        "launched walredo process"
+                    );
+                    self.redo_process
+                        .set(ProcessOnceCell::Spawned(Arc::clone(&proc)), permit);
+                    proc
+                }
+            };

            let started_at = std::time::Instant::now();

@@ -299,12 +404,17 @@ impl PostgresRedoManager {
                match self.redo_process.get() {
                    None => (),
                    Some(guard) => {
-                        if Arc::ptr_eq(&proc, &*guard) {
-                            // We're the first to observe an error from `proc`, it's our job to take it out of rotation.
-                            guard.take_and_deinit();
-                        } else {
-                            // Another task already spawned another redo process (further up in this method)
-                            // and put it into `redo_process`. Do nothing, our view of the world is behind.
+                        match &*guard {
+                            ProcessOnceCell::ManagerShutDown => {}
+                            ProcessOnceCell::Spawned(guard_proc) => {
+                                if Arc::ptr_eq(&proc, guard_proc) {
+                                    // We're the first to observe an error from `proc`, it's our job to take it out of rotation.
+                                    guard.take_and_deinit();
+                                } else {
+                                    // Another task already spawned another redo process (further up in this method)
+                                    // and put it into `redo_process`. Do nothing, our view of the world is behind.
+                                }
+                            }
                        }
                    }
                }
@@ -315,7 +425,7 @@ impl PostgresRedoManager {
            }
            n_attempts += 1;
            if n_attempts > MAX_RETRY_ATTEMPTS || result.is_ok() {
-                return result;
+                return result.map_err(Error::Other);
            }
        }
    }
@@ -329,7 +439,7 @@ impl PostgresRedoManager {
        lsn: Lsn,
        base_img: Option<Bytes>,
        records: &[(Lsn, NeonWalRecord)],
-    ) -> anyhow::Result<Bytes> {
+    ) -> Result<Bytes, Error> {
        let start_time = Instant::now();

        let mut page = BytesMut::new();
@@ -338,7 +448,7 @@ impl PostgresRedoManager {
            page.extend_from_slice(&fpi[..]);
        } else {
            // All the current WAL record types that we can handle require a base image.
-            anyhow::bail!("invalid neon WAL redo request with no base image");
+            bail!("invalid neon WAL redo request with no base image");
        }

        // Apply all the WAL records in the batch
--- a/pgxn/neon/Makefile
+++ b/pgxn/neon/Makefile
@@ -6,6 +6,7 @@ OBJS = \
 	$(WIN32RES) \
 	extension_server.o \
 	file_cache.o \
+	hll.o \
 	libpagestore.o \
 	neon.o \
 	neon_utils.o \
@@ -22,7 +23,7 @@ SHLIB_LINK_INTERNAL = $(libpq)
 SHLIB_LINK = -lcurl

 EXTENSION = neon
-DATA = neon--1.0.sql neon--1.0--1.1.sql neon--1.1--1.2.sql neon--1.2--1.3.sql neon--1.3--1.2.sql neon--1.2--1.1.sql neon--1.1--1.0.sql
+DATA = neon--1.0.sql neon--1.0--1.1.sql neon--1.1--1.2.sql neon--1.2--1.3.sql neon--1.3--1.2.sql neon--1.2--1.1.sql neon--1.1--1.0.sql  neon--1.3--1.4.sql neon--1.4--1.3.sql
 PGFILEDESC = "neon - cloud storage for PostgreSQL"

 EXTRA_CLEAN = \
--- a/pgxn/neon/file_cache.c
+++ b/pgxn/neon/file_cache.c
@@ -26,7 +26,6 @@
 #include "miscadmin.h"
 #include "pagestore_client.h"
 #include "common/hashfn.h"
-#include "lib/hyperloglog.h"
 #include "pgstat.h"
 #include "postmaster/bgworker.h"
 #include RELFILEINFO_HDR
@@ -40,6 +39,8 @@
 #include "utils/dynahash.h"
 #include "utils/guc.h"

+#include "hll.h"
+
 /*
 * Local file cache is used to temporary store relations pages in local file system.
 * All blocks of all relations are stored inside one file and addressed using shared hash map.
@@ -62,7 +63,6 @@
 #define BLOCKS_PER_CHUNK	128 /* 1Mb chunk */
 #define MB					((uint64)1024*1024)

-#define HYPER_LOG_LOG_BIT_WIDTH   10
 #define SIZE_MB_TO_CHUNKS(size) ((uint32)((size) * MB / BLCKSZ / BLOCKS_PER_CHUNK))

 typedef struct FileCacheEntry
@@ -87,8 +87,7 @@ typedef struct FileCacheControl
 	uint64		writes;
 	dlist_head	lru;			/* double linked list for LRU replacement
 								 * algorithm */
-	hyperLogLogState wss_estimation; /* estimation of wroking set size */
-	uint8_t		hyperloglog_hashes[(1 << HYPER_LOG_LOG_BIT_WIDTH) + 1];
+	HyperLogLogState wss_estimation; /* estimation of working set size */
 } FileCacheControl;

 static HTAB *lfc_hash;
@@ -238,12 +237,7 @@ lfc_shmem_startup(void)
 		dlist_init(&lfc_ctl->lru);

 		/* Initialize hyper-log-log structure for estimating working set size */
-		initHyperLogLog(&lfc_ctl->wss_estimation, HYPER_LOG_LOG_BIT_WIDTH);
-
-		/* We need hashes in shared memory */
-		pfree(lfc_ctl->wss_estimation.hashesArr);
-		memset(lfc_ctl->hyperloglog_hashes, 0, sizeof lfc_ctl->hyperloglog_hashes);
-		lfc_ctl->wss_estimation.hashesArr = lfc_ctl->hyperloglog_hashes;
+		initSHLL(&lfc_ctl->wss_estimation);

 		/* Recreate file cache on restart */
 		fd = BasicOpenFile(lfc_path, O_RDWR | O_CREAT | O_TRUNC);
@@ -545,7 +539,7 @@ lfc_read(NRelFileInfo rinfo, ForkNumber forkNum, BlockNumber blkno,

 	/* Approximate working set */
 	tag.blockNum = blkno;
-	addHyperLogLog(&lfc_ctl->wss_estimation, hash_bytes((uint8_t const*)&tag, sizeof(tag)));
+	addSHLL(&lfc_ctl->wss_estimation, hash_bytes((uint8_t const*)&tag, sizeof(tag)));

 	if (entry == NULL || (entry->bitmap[chunk_offs >> 5] & (1 << (chunk_offs & 31))) == 0)
 	{
@@ -986,20 +980,38 @@ local_cache_pages(PG_FUNCTION_ARGS)
 		SRF_RETURN_DONE(funcctx);
 }

+PG_FUNCTION_INFO_V1(approximate_working_set_size_seconds);
+
+Datum
+approximate_working_set_size_seconds(PG_FUNCTION_ARGS)
+{
+	if (lfc_size_limit != 0)
+	{
+		int32 dc;
+		time_t duration = PG_ARGISNULL(0) ? (time_t)-1 : PG_GETARG_INT32(0);
+		LWLockAcquire(lfc_lock, LW_SHARED);
+		dc = (int32) estimateSHLL(&lfc_ctl->wss_estimation, duration);
+		LWLockRelease(lfc_lock);
+		PG_RETURN_INT32(dc);
+	}
+	PG_RETURN_NULL();
+}
+
 PG_FUNCTION_INFO_V1(approximate_working_set_size);

 Datum
 approximate_working_set_size(PG_FUNCTION_ARGS)
 {
-	int32 dc = -1;
 	if (lfc_size_limit != 0)
 	{
+		int32 dc;
 		bool reset = PG_GETARG_BOOL(0);
 		LWLockAcquire(lfc_lock, reset ? LW_EXCLUSIVE : LW_SHARED);
-		dc = (int32) estimateHyperLogLog(&lfc_ctl->wss_estimation);
+		dc = (int32) estimateSHLL(&lfc_ctl->wss_estimation, (time_t)-1);
 		if (reset)
-			memset(lfc_ctl->hyperloglog_hashes, 0, sizeof lfc_ctl->hyperloglog_hashes);
+			memset(lfc_ctl->wss_estimation.regs, 0, sizeof lfc_ctl->wss_estimation.regs);
 		LWLockRelease(lfc_lock);
+		PG_RETURN_INT32(dc);
 	}
-	PG_RETURN_INT32(dc);
+	PG_RETURN_NULL();
 }
--- a/pgxn/neon/hll.c
+++ b/pgxn/neon/hll.c
@@ -0,0 +1,193 @@
+/*-------------------------------------------------------------------------
+ *
+ * hll.c
+ *	  Sliding HyperLogLog cardinality estimator
+ *
+ * Portions Copyright (c) 2014-2023, PostgreSQL Global Development Group
+ *
+ * Implements https://hal.science/hal-00465313/document
+ * 
+ * Based on Hideaki Ohno's C++ implementation.  This is probably not ideally
+ * suited to estimating the cardinality of very large sets;  in particular, we
+ * have not attempted to further optimize the implementation as described in
+ * the Heule, Nunkesser and Hall paper "HyperLogLog in Practice: Algorithmic
+ * Engineering of a State of The Art Cardinality Estimation Algorithm".
+ *
+ * A sparse representation of HyperLogLog state is used, with fixed space
+ * overhead.
+ *
+ * The copyright terms of Ohno's original version (the MIT license) follow.
+ *
+ * IDENTIFICATION
+ *	  src/backend/lib/hyperloglog.c
+ *
+ *-------------------------------------------------------------------------
+ */
+
+/*
+ * Copyright (c) 2013 Hideaki Ohno <hide.o.j55{at}gmail.com>
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the 'Software'), to
+ * deal in the Software without restriction, including without limitation the
+ * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
+ * sell copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED 'AS IS', WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ */
+
+#include <math.h>
+
+#include "postgres.h"
+#include "funcapi.h"
+#include "port/pg_bitutils.h"
+#include "utils/timestamp.h"
+#include "hll.h"
+
+
+#define POW_2_32			(4294967296.0)
+#define NEG_POW_2_32		(-4294967296.0)
+
+#define ALPHA_MM ((0.7213 / (1.0 + 1.079 / HLL_N_REGISTERS)) * HLL_N_REGISTERS * HLL_N_REGISTERS)
+
+/*
+ * Worker for addHyperLogLog().
+ *
+ * Calculates the position of the first set bit in first b bits of x argument
+ * starting from the first, reading from most significant to least significant
+ * bits.
+ *
+ * Example (when considering fist 10 bits of x):
+ *
+ * rho(x = 0b1000000000)   returns 1
+ * rho(x = 0b0010000000)   returns 3
+ * rho(x = 0b0000000000)   returns b + 1
+ *
+ * "The binary address determined by the first b bits of x"
+ *
+ * Return value "j" used to index bit pattern to watch.
+ */
+static inline uint8
+rho(uint32 x, uint8 b)
+{
+	uint8		j = 1;
+
+	if (x == 0)
+		return b + 1;
+
+	j = 32 - pg_leftmost_one_pos32(x);
+
+	if (j > b)
+		return b + 1;
+
+	return j;
+}
+
+/*
+ * Initialize HyperLogLog track state
+ */
+void
+initSHLL(HyperLogLogState *cState)
+{
+	memset(cState->regs, 0, sizeof(cState->regs));
+}
+
+/*
+ * Adds element to the estimator, from caller-supplied hash.
+ *
+ * It is critical that the hash value passed be an actual hash value, typically
+ * generated using hash_any().  The algorithm relies on a specific bit-pattern
+ * observable in conjunction with stochastic averaging.  There must be a
+ * uniform distribution of bits in hash values for each distinct original value
+ * observed.
+ */
+void
+addSHLL(HyperLogLogState *cState, uint32 hash)
+{
+	uint8		count;
+	uint32		index;
+	size_t		i;
+	size_t		j;
+
+	TimestampTz	now = GetCurrentTimestamp();
+	/* Use the first "k" (registerWidth) bits as a zero based index */
+	index = hash >> HLL_C_BITS;
+
+	/* Compute the rank of the remaining 32 - "k" (registerWidth) bits */
+	count = rho(hash << HLL_BIT_WIDTH, HLL_C_BITS);
+
+	cState->regs[index][count] = now;
+}
+
+static uint8
+getMaximum(const TimestampTz* reg, TimestampTz since)
+{
+	uint8 max = 0;
+
+	for (size_t i = 0; i < HLL_C_BITS + 1; i++)
+	{
+		if (reg[i] >= since)
+		{
+			max = i;
+		}
+	}
+
+	return max;
+}
+
+
+/*
+ * Estimates cardinality, based on elements added so far
+ */
+double
+estimateSHLL(HyperLogLogState *cState, time_t duration)
+{
+	double		result;
+	double		sum = 0.0;
+	size_t		i;
+	uint8       R[HLL_N_REGISTERS];
+	/* 0 indicates uninitialized timestamp, so if we need to cover the whole range than starts with 1 */
+	TimestampTz since = duration == (time_t)-1 ? 1 : GetCurrentTimestamp() - duration * USECS_PER_SEC;
+
+	for (i = 0; i < HLL_N_REGISTERS; i++)
+	{
+		R[i] = getMaximum(cState->regs[i], since);
+		sum += 1.0 / pow(2.0, R[i]);
+	}
+
+	/* result set to "raw" HyperLogLog estimate (E in the HyperLogLog paper) */
+	result = ALPHA_MM / sum;
+
+	if (result <= (5.0 / 2.0) * HLL_N_REGISTERS)
+	{
+		/* Small range correction */
+		int			zero_count = 0;
+
+		for (i = 0; i < HLL_N_REGISTERS; i++)
+		{
+			zero_count += R[i] == 0;
+		}
+
+		if (zero_count != 0)
+			result = HLL_N_REGISTERS * log((double) HLL_N_REGISTERS /
+										   zero_count);
+	}
+	else if (result > (1.0 / 30.0) * POW_2_32)
+	{
+		/* Large range correction */
+		result = NEG_POW_2_32 * log(1.0 - (result / POW_2_32));
+	}
+
+	return result;
+}
+
--- a/pgxn/neon/hll.h
+++ b/pgxn/neon/hll.h
@@ -0,0 +1,86 @@
+/*-------------------------------------------------------------------------
+ *
+ * hll.h
+ *	  Sliding HyperLogLog cardinality estimator
+ *
+ * Portions Copyright (c) 2014-2023, PostgreSQL Global Development Group
+ *
+ * Implements https://hal.science/hal-00465313/document
+ * 
+ * Based on Hideaki Ohno's C++ implementation.  This is probably not ideally
+ * suited to estimating the cardinality of very large sets;  in particular, we
+ * have not attempted to further optimize the implementation as described in
+ * the Heule, Nunkesser and Hall paper "HyperLogLog in Practice: Algorithmic
+ * Engineering of a State of The Art Cardinality Estimation Algorithm".
+ *
+ * A sparse representation of HyperLogLog state is used, with fixed space
+ * overhead.
+ *
+ * The copyright terms of Ohno's original version (the MIT license) follow.
+ *
+ * IDENTIFICATION
+ *	  src/backend/lib/hyperloglog.c
+ *
+ *-------------------------------------------------------------------------
+ */
+
+/*
+ * Copyright (c) 2013 Hideaki Ohno <hide.o.j55{at}gmail.com>
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the 'Software'), to
+ * deal in the Software without restriction, including without limitation the
+ * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
+ * sell copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED 'AS IS', WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ */
+
+#ifndef HLL_H
+#define HLL_H
+
+#define HLL_BIT_WIDTH   10
+#define HLL_C_BITS      (32 - HLL_BIT_WIDTH)
+#define HLL_N_REGISTERS (1 << HLL_BIT_WIDTH)
+
+/*
+ * HyperLogLog is an approximate technique for computing the number of distinct
+ * entries in a set.  Importantly, it does this by using a fixed amount of
+ * memory.  See the 2007 paper "HyperLogLog: the analysis of a near-optimal
+ * cardinality estimation algorithm" for more.
+ *
+ * Instead of a single counter for every bits register, we have a timestamp
+ * for every valid number of bits we can encounter. Every time we encounter
+ * a certain number of bits, we update the timestamp in those registers to
+ * the current timestamp.
+ *
+ * We can query the sketch's stored cardinality for the range of some timestamp
+ * up to now: For each register, we return the highest bits bucket that has a
+ * modified timestamp >= the query timestamp. This value is the number of bits
+ * for this register in the normal HLL calculation.
+ *
+ * The memory usage is 2^B * (C + 1) * sizeof(TimetampTz), or 184kiB.
+ * Usage could be halved if we decide to reduce the required time dimension
+ * precision; as 32 bits in second precision should be enough for statistics.
+ * However, that is not yet implemented.
+ */
+typedef struct HyperLogLogState
+{
+	TimestampTz regs[HLL_N_REGISTERS][HLL_C_BITS + 1];
+} HyperLogLogState;
+
+extern void   initSHLL(HyperLogLogState *cState);
+extern void   addSHLL(HyperLogLogState *cState, uint32 hash);
+extern double estimateSHLL(HyperLogLogState *cState, time_t dutration);
+
+#endif
--- a/Show More
+++ b/Show More