Reduce number of iteration in test_physical_replication to reduce test time

Fix test_physical_replication test taken in acount autocommit behaviour of psycopg
refactor(pageserver): use tokio::signal instead of spawn_blocking (#7332 )
2026-08-13 17:51:33 +00:00 · 2024-05-22 11:52:31 +03:00 · 2024-04-08 17:37:48 +03:00 · 2024-04-08 09:35:32 +00:00 · 2024-04-08 09:01:38 +03:00 · 2024-04-07 21:21:18 +00:00
250 changed files with 12292 additions and 4593 deletions
@@ -22,6 +22,7 @@
 !s3_scrubber/
 !safekeeper/
 !storage_broker/
+!storage_controller/
 !trace/
 !vendor/postgres-*/
 !workspace_hack/
@@ -147,15 +147,16 @@ jobs:
            "neonvm-captest-new"
          ],
          "db_size": [ "10gb" ],
-          "include": [{ "platform": "neon-captest-freetier",   "db_size": "3gb"  },
-                      { "platform": "neon-captest-new",        "db_size": "50gb" },
-                      { "platform": "neonvm-captest-freetier", "db_size": "3gb"  },
-                      { "platform": "neonvm-captest-new",      "db_size": "50gb" }]
+          "include": [{ "platform": "neon-captest-freetier",         "db_size": "3gb"  },
+                      { "platform": "neon-captest-new",              "db_size": "50gb" },
+                      { "platform": "neonvm-captest-freetier",       "db_size": "3gb"  },
+                      { "platform": "neonvm-captest-new",            "db_size": "50gb" },
+                      { "platform": "neonvm-captest-sharding-reuse", "db_size": "50gb" }]
        }'

        if [ "$(date +%A)" = "Saturday" ]; then
          matrix=$(echo "$matrix" | jq '.include += [{ "platform": "rds-postgres", "db_size": "10gb"},
-                                                   { "platform": "rds-aurora",   "db_size": "50gb"}]')
+                                                     { "platform": "rds-aurora",   "db_size": "50gb"}]')
        fi

        echo "matrix=$(echo "$matrix" | jq --compact-output '.')" >> $GITHUB_OUTPUT
@@ -171,7 +172,7 @@ jobs:

        if [ "$(date +%A)" = "Saturday" ] || [ ${RUN_AWS_RDS_AND_AURORA} = "true" ]; then
          matrix=$(echo "$matrix" | jq '.include += [{ "platform": "rds-postgres" },
-                                                   { "platform": "rds-aurora"   }]')
+                                                     { "platform": "rds-aurora"   }]')
        fi

        echo "matrix=$(echo "$matrix" | jq --compact-output '.')" >> $GITHUB_OUTPUT
@@ -190,7 +191,7 @@ jobs:

        if [ "$(date +%A)" = "Saturday" ] || [ ${RUN_AWS_RDS_AND_AURORA} = "true" ]; then
          matrix=$(echo "$matrix" | jq '.include += [{ "platform": "rds-postgres", "scale": "10" },
-                                                    { "platform": "rds-aurora",   "scale": "10" }]')
+                                                     { "platform": "rds-aurora",   "scale": "10" }]')
        fi

        echo "matrix=$(echo "$matrix" | jq --compact-output '.')" >> $GITHUB_OUTPUT
@@ -253,6 +254,9 @@ jobs:
          neon-captest-reuse)
            CONNSTR=${{ secrets.BENCHMARK_CAPTEST_CONNSTR }}
            ;;
+          neonvm-captest-sharding-reuse)
+            CONNSTR=${{ secrets.BENCHMARK_CAPTEST_SHARDING_CONNSTR }}
+            ;;
          neon-captest-new | neon-captest-freetier | neonvm-captest-new | neonvm-captest-freetier)
            CONNSTR=${{ steps.create-neon-project.outputs.dsn }}
            ;;
@@ -270,11 +274,15 @@ jobs:

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

-        QUERY="SELECT version();"
+        QUERIES=("SELECT version()")
        if [[ "${PLATFORM}" = "neon"* ]]; then
-          QUERY="${QUERY} SHOW neon.tenant_id; SHOW neon.timeline_id;"
+          QUERIES+=("SHOW neon.tenant_id")
+          QUERIES+=("SHOW neon.timeline_id")
        fi
-        psql ${CONNSTR} -c "${QUERY}"
+
+        for q in "${QUERIES[@]}"; do
+          psql ${CONNSTR} -c "${q}"
+        done

    - name: Benchmark init
      uses: ./.github/actions/run-python-test-set
@@ -401,11 +409,15 @@ jobs:

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

-        QUERY="SELECT version();"
+        QUERIES=("SELECT version()")
        if [[ "${PLATFORM}" = "neon"* ]]; then
-          QUERY="${QUERY} SHOW neon.tenant_id; SHOW neon.timeline_id;"
+          QUERIES+=("SHOW neon.tenant_id")
+          QUERIES+=("SHOW neon.timeline_id")
        fi
-        psql ${CONNSTR} -c "${QUERY}"
+
+        for q in "${QUERIES[@]}"; do
+          psql ${CONNSTR} -c "${q}"
+        done

    - name: ClickBench benchmark
      uses: ./.github/actions/run-python-test-set
@@ -507,11 +519,15 @@ jobs:

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

-        QUERY="SELECT version();"
+        QUERIES=("SELECT version()")
        if [[ "${PLATFORM}" = "neon"* ]]; then
-          QUERY="${QUERY} SHOW neon.tenant_id; SHOW neon.timeline_id;"
+          QUERIES+=("SHOW neon.tenant_id")
+          QUERIES+=("SHOW neon.timeline_id")
        fi
-        psql ${CONNSTR} -c "${QUERY}"
+
+        for q in "${QUERIES[@]}"; do
+          psql ${CONNSTR} -c "${q}"
+        done

    - name: Run TPC-H benchmark
      uses: ./.github/actions/run-python-test-set
@@ -597,11 +613,15 @@ jobs:

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

-        QUERY="SELECT version();"
+        QUERIES=("SELECT version()")
        if [[ "${PLATFORM}" = "neon"* ]]; then
-          QUERY="${QUERY} SHOW neon.tenant_id; SHOW neon.timeline_id;"
+          QUERIES+=("SHOW neon.tenant_id")
+          QUERIES+=("SHOW neon.timeline_id")
        fi
-        psql ${CONNSTR} -c "${QUERY}"
+
+        for q in "${QUERIES[@]}"; do
+          psql ${CONNSTR} -c "${q}"
+        done

    - name: Run user examples
      uses: ./.github/actions/run-python-test-set
@@ -1121,18 +1121,36 @@ 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
-
-            # TODO: move deployPreprodRegion to release (`"$GITHUB_REF_NAME" == "release"` block), once Staging support different compute tag prefixes for different regions
-            gh workflow --repo neondatabase/aws run deploy-dev.yml --ref main -f branch=main -f dockerTag=${{needs.tag.outputs.build-tag}} -f deployPreprodRegion=true
          elif [[ "$GITHUB_REF_NAME" == "release" ]]; then
+            gh workflow --repo neondatabase/aws run deploy-dev.yml --ref main \
+              -f deployPgSniRouter=false \
+              -f deployProxy=false \
+              -f deployStorage=true \
+              -f deployStorageBroker=true \
+              -f deployStorageController=true \
+              -f branch=main \
+              -f dockerTag=${{needs.tag.outputs.build-tag}} \
+              -f deployPreprodRegion=true
+
            gh workflow --repo neondatabase/aws run deploy-prod.yml --ref main \
              -f deployPgSniRouter=false \
              -f deployProxy=false \
              -f deployStorage=true \
              -f deployStorageBroker=true \
+              -f deployStorageController=true \
              -f branch=main \
              -f dockerTag=${{needs.tag.outputs.build-tag}}
          elif [[ "$GITHUB_REF_NAME" == "release-proxy" ]]; then
+            gh workflow --repo neondatabase/aws run deploy-dev.yml --ref main \
+              -f deployPgSniRouter=true \
+              -f deployProxy=true \
+              -f deployStorage=false \
+              -f deployStorageBroker=false \
+              -f deployStorageController=false \
+              -f branch=main \
+              -f dockerTag=${{needs.tag.outputs.build-tag}} \
+              -f deployPreprodRegion=true
+
            gh workflow --repo neondatabase/aws run deploy-proxy-prod.yml --ref main \
              -f deployPgSniRouter=true \
              -f deployProxy=true \
@@ -62,14 +62,14 @@ jobs:

  trigger-e2e-tests:
    needs: [ tag ]
-    runs-on: [ self-hosted, gen3, small ]
+    runs-on: ubuntu-latest
    env:
      TAG: ${{ needs.tag.outputs.build-tag }}
-    container:
-      image: 369495373322.dkr.ecr.eu-central-1.amazonaws.com/base:pinned
-      options: --init
    steps:
      - name: check if ecr image are present
+        env:
+          AWS_ACCESS_KEY_ID: ${{ secrets.AWS_ACCESS_KEY_DEV }}
+          AWS_SECRET_ACCESS_KEY: ${{ secrets.AWS_SECRET_KEY_DEV }}
        run: |
          for REPO in neon compute-tools compute-node-v14 vm-compute-node-v14 compute-node-v15 vm-compute-node-v15 compute-node-v16 vm-compute-node-v16; do
            OUTPUT=$(aws ecr describe-images --repository-name ${REPO} --region eu-central-1 --query "imageDetails[?imageTags[?contains(@, '${TAG}')]]" --output text)
@@ -79,41 +79,55 @@ jobs:
            fi
          done

-      - name: Set PR's status to pending and request a remote CI test
+      - name: Set e2e-platforms
+        id: e2e-platforms
+        env:
+          PR_NUMBER: ${{ github.event.pull_request.number }}
+          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
        run: |
-          # For pull requests, GH Actions set "github.sha" variable to point at a fake merge commit
-          # but we need to use a real sha of a latest commit in the PR's branch for the e2e job,
-          # to place a job run status update later.
-          COMMIT_SHA=${{ github.event.pull_request.head.sha }}
-          # For non-PR kinds of runs, the above will produce an empty variable, pick the original sha value for those
-          COMMIT_SHA=${COMMIT_SHA:-${{ github.sha }}}
+          # Default set of platforms to run e2e tests on
+          platforms='["docker", "k8s"]'

-          REMOTE_REPO="${{ github.repository_owner }}/cloud"
+          # If the PR changes vendor/, pgxn/ or libs/vm_monitor/ directories, or Dockerfile.compute-node, add k8s-neonvm to the list of platforms.
+          # If the workflow run is not a pull request, add k8s-neonvm to the list.
+          if [ "$GITHUB_EVENT_NAME" == "pull_request" ]; then
+            for f in $(gh api "/repos/${GITHUB_REPOSITORY}/pulls/${PR_NUMBER}/files" --paginate --jq '.[].filename'); do
+              case "$f" in
+                vendor/*|pgxn/*|libs/vm_monitor/*|Dockerfile.compute-node)
+                  platforms=$(echo "${platforms}" | jq --compact-output '. += ["k8s-neonvm"] | unique')
+                  ;;
+                *)
+                  # no-op
+                  ;;
+              esac
+            done
+          else
+            platforms=$(echo "${platforms}" | jq --compact-output '. += ["k8s-neonvm"] | unique')
+          fi

-          curl -f -X POST \
-          https://api.github.com/repos/${{ github.repository }}/statuses/$COMMIT_SHA \
-          -H "Accept: application/vnd.github.v3+json" \
-          --user "${{ secrets.CI_ACCESS_TOKEN }}" \
-          --data \
-            "{
-              \"state\": \"pending\",
-              \"context\": \"neon-cloud-e2e\",
-              \"description\": \"[$REMOTE_REPO] Remote CI job is about to start\"
-            }"
+          echo "e2e-platforms=${platforms}" | tee -a $GITHUB_OUTPUT

-          curl -f -X POST \
-          https://api.github.com/repos/$REMOTE_REPO/actions/workflows/testing.yml/dispatches \
-          -H "Accept: application/vnd.github.v3+json" \
-          --user "${{ secrets.CI_ACCESS_TOKEN }}" \
-          --data \
-            "{
-              \"ref\": \"main\",
-              \"inputs\": {
-                \"ci_job_name\": \"neon-cloud-e2e\",
-                \"commit_hash\": \"$COMMIT_SHA\",
-                \"remote_repo\": \"${{ github.repository }}\",
-                \"storage_image_tag\": \"${TAG}\",
-                \"compute_image_tag\": \"${TAG}\",
-                \"concurrency_group\": \"${{ env.E2E_CONCURRENCY_GROUP }}\"
-              }
-            }"
+      - name: Set PR's status to pending and request a remote CI test
+        env:
+          E2E_PLATFORMS: ${{ steps.e2e-platforms.outputs.e2e-platforms }}
+          COMMIT_SHA: ${{ github.event.pull_request.head.sha || github.sha }}
+          GH_TOKEN: ${{ secrets.CI_ACCESS_TOKEN }}
+        run: |
+          REMOTE_REPO="${GITHUB_REPOSITORY_OWNER}/cloud"
+
+          gh api "/repos/${GITHUB_REPOSITORY}/statuses/${COMMIT_SHA}" \
+            --method POST \
+            --raw-field "state=pending" \
+            --raw-field "description=[$REMOTE_REPO] Remote CI job is about to start" \
+            --raw-field "context=neon-cloud-e2e"
+
+          gh workflow --repo ${REMOTE_REPO} \
+            run testing.yml \
+              --ref "main" \
+              --raw-field "ci_job_name=neon-cloud-e2e" \
+              --raw-field "commit_hash=$COMMIT_SHA" \
+              --raw-field "remote_repo=${GITHUB_REPOSITORY}" \
+              --raw-field "storage_image_tag=${TAG}" \
+              --raw-field "compute_image_tag=${TAG}" \
+              --raw-field "concurrency_group=${E2E_CONCURRENCY_GROUP}" \
+              --raw-field "e2e-platforms=${E2E_PLATFORMS}"
@@ -1,12 +1,13 @@
 /compute_tools/ @neondatabase/control-plane @neondatabase/compute
-/control_plane/attachment_service @neondatabase/storage
+/storage_controller @neondatabase/storage
 /libs/pageserver_api/ @neondatabase/storage
-/libs/postgres_ffi/ @neondatabase/compute
+/libs/postgres_ffi/ @neondatabase/compute @neondatabase/safekeepers
 /libs/remote_storage/ @neondatabase/storage
 /libs/safekeeper_api/ @neondatabase/safekeepers
 /libs/vm_monitor/ @neondatabase/autoscaling
 /pageserver/ @neondatabase/storage
 /pgxn/ @neondatabase/compute
+/pgxn/neon/ @neondatabase/compute @neondatabase/safekeepers
 /proxy/ @neondatabase/proxy
 /safekeeper/ @neondatabase/safekeepers
 /vendor/ @neondatabase/compute
@@ -270,41 +270,6 @@ dependencies = [
 "critical-section",
 ]

-[[package]]
-name = "attachment_service"
-version = "0.1.0"
-dependencies = [
- "anyhow",
- "aws-config",
- "aws-sdk-secretsmanager",
- "camino",
- "clap",
- "control_plane",
- "diesel",
- "diesel_migrations",
- "fail",
- "futures",
- "git-version",
- "hex",
- "humantime",
- "hyper",
- "metrics",
- "once_cell",
- "pageserver_api",
- "pageserver_client",
- "postgres_connection",
- "r2d2",
- "reqwest",
- "serde",
- "serde_json",
- "thiserror",
- "tokio",
- "tokio-util",
- "tracing",
- "utils",
- "workspace_hack",
-]
-
 [[package]]
 name = "autocfg"
 version = "1.1.0"
@@ -343,9 +308,9 @@ dependencies = [

 [[package]]
 name = "aws-credential-types"
-version = "1.1.4"
+version = "1.1.8"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "33cc49dcdd31c8b6e79850a179af4c367669150c7ac0135f176c61bec81a70f7"
+checksum = "fa8587ae17c8e967e4b05a62d495be2fb7701bec52a97f7acfe8a29f938384c8"
 dependencies = [
 "aws-smithy-async",
 "aws-smithy-runtime-api",
@@ -355,9 +320,9 @@ dependencies = [

 [[package]]
 name = "aws-runtime"
-version = "1.1.4"
+version = "1.1.8"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "eb031bff99877c26c28895766f7bb8484a05e24547e370768d6cc9db514662aa"
+checksum = "b13dc54b4b49f8288532334bba8f87386a40571c47c37b1304979b556dc613c8"
 dependencies = [
 "aws-credential-types",
 "aws-sigv4",
@@ -377,6 +342,29 @@ dependencies = [
 "uuid",
 ]

+[[package]]
+name = "aws-sdk-iam"
+version = "1.17.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b8ae76026bfb1b80a6aed0bb400c1139cd9c0563e26bce1986cd021c6a968c7b"
+dependencies = [
+ "aws-credential-types",
+ "aws-runtime",
+ "aws-smithy-async",
+ "aws-smithy-http",
+ "aws-smithy-json",
+ "aws-smithy-query",
+ "aws-smithy-runtime",
+ "aws-smithy-runtime-api",
+ "aws-smithy-types",
+ "aws-smithy-xml",
+ "aws-types",
+ "http 0.2.9",
+ "once_cell",
+ "regex-lite",
+ "tracing",
+]
+
 [[package]]
 name = "aws-sdk-s3"
 version = "1.14.0"
@@ -406,29 +394,6 @@ dependencies = [
 "url",
 ]

-[[package]]
-name = "aws-sdk-secretsmanager"
-version = "1.14.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "0a0b64e61e7d632d9df90a2e0f32630c68c24960cab1d27d848718180af883d3"
-dependencies = [
- "aws-credential-types",
- "aws-runtime",
- "aws-smithy-async",
- "aws-smithy-http",
- "aws-smithy-json",
- "aws-smithy-runtime",
- "aws-smithy-runtime-api",
- "aws-smithy-types",
- "aws-types",
- "bytes",
- "fastrand 2.0.0",
- "http 0.2.9",
- "once_cell",
- "regex-lite",
- "tracing",
-]
-
 [[package]]
 name = "aws-sdk-sso"
 version = "1.12.0"
@@ -498,9 +463,9 @@ dependencies = [

 [[package]]
 name = "aws-sigv4"
-version = "1.1.4"
+version = "1.2.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "c371c6b0ac54d4605eb6f016624fb5c7c2925d315fdf600ac1bf21b19d5f1742"
+checksum = "11d6f29688a4be9895c0ba8bef861ad0c0dac5c15e9618b9b7a6c233990fc263"
 dependencies = [
 "aws-credential-types",
 "aws-smithy-eventstream",
@@ -513,7 +478,7 @@ dependencies = [
 "hex",
 "hmac",
 "http 0.2.9",
- "http 1.0.0",
+ "http 1.1.0",
 "once_cell",
 "p256",
 "percent-encoding",
@@ -527,9 +492,9 @@ dependencies = [

 [[package]]
 name = "aws-smithy-async"
-version = "1.1.4"
+version = "1.1.8"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "72ee2d09cce0ef3ae526679b522835d63e75fb427aca5413cd371e490d52dcc6"
+checksum = "d26ea8fa03025b2face2b3038a63525a10891e3d8829901d502e5384a0d8cd46"
 dependencies = [
 "futures-util",
 "pin-project-lite",
@@ -570,9 +535,9 @@ dependencies = [

 [[package]]
 name = "aws-smithy-http"
-version = "0.60.4"
+version = "0.60.7"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "dab56aea3cd9e1101a0a999447fb346afb680ab1406cebc44b32346e25b4117d"
+checksum = "3f10fa66956f01540051b0aa7ad54574640f748f9839e843442d99b970d3aff9"
 dependencies = [
 "aws-smithy-eventstream",
 "aws-smithy-runtime-api",
@@ -591,18 +556,18 @@ dependencies = [

 [[package]]
 name = "aws-smithy-json"
-version = "0.60.4"
+version = "0.60.7"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "fd3898ca6518f9215f62678870064398f00031912390efd03f1f6ef56d83aa8e"
+checksum = "4683df9469ef09468dad3473d129960119a0d3593617542b7d52086c8486f2d6"
 dependencies = [
 "aws-smithy-types",
 ]

 [[package]]
 name = "aws-smithy-query"
-version = "0.60.4"
+version = "0.60.7"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "bda4b1dfc9810e35fba8a620e900522cd1bd4f9578c446e82f49d1ce41d2e9f9"
+checksum = "f2fbd61ceb3fe8a1cb7352e42689cec5335833cd9f94103a61e98f9bb61c64bb"
 dependencies = [
 "aws-smithy-types",
 "urlencoding",
@@ -610,9 +575,9 @@ dependencies = [

 [[package]]
 name = "aws-smithy-runtime"
-version = "1.1.4"
+version = "1.1.8"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "fafdab38f40ad7816e7da5dec279400dd505160780083759f01441af1bbb10ea"
+checksum = "ec81002d883e5a7fd2bb063d6fb51c4999eb55d404f4fff3dd878bf4733b9f01"
 dependencies = [
 "aws-smithy-async",
 "aws-smithy-http",
@@ -635,14 +600,15 @@ dependencies = [

 [[package]]
 name = "aws-smithy-runtime-api"
-version = "1.1.4"
+version = "1.2.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "c18276dd28852f34b3bf501f4f3719781f4999a51c7bff1a5c6dc8c4529adc29"
+checksum = "9acb931e0adaf5132de878f1398d83f8677f90ba70f01f65ff87f6d7244be1c5"
 dependencies = [
 "aws-smithy-async",
 "aws-smithy-types",
 "bytes",
 "http 0.2.9",
+ "http 1.1.0",
 "pin-project-lite",
 "tokio",
 "tracing",
@@ -651,9 +617,9 @@ dependencies = [

 [[package]]
 name = "aws-smithy-types"
-version = "1.1.4"
+version = "1.1.8"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "bb3e134004170d3303718baa2a4eb4ca64ee0a1c0a7041dca31b38be0fb414f3"
+checksum = "abe14dceea1e70101d38fbf2a99e6a34159477c0fb95e68e05c66bd7ae4c3729"
 dependencies = [
 "base64-simd",
 "bytes",
@@ -674,18 +640,18 @@ dependencies = [

 [[package]]
 name = "aws-smithy-xml"
-version = "0.60.4"
+version = "0.60.7"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "8604a11b25e9ecaf32f9aa56b9fe253c5e2f606a3477f0071e96d3155a5ed218"
+checksum = "872c68cf019c0e4afc5de7753c4f7288ce4b71663212771bf5e4542eb9346ca9"
 dependencies = [
 "xmlparser",
 ]

 [[package]]
 name = "aws-types"
-version = "1.1.4"
+version = "1.1.8"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "789bbe008e65636fe1b6dbbb374c40c8960d1232b96af5ff4aec349f9c4accf4"
+checksum = "0dbf2f3da841a8930f159163175cf6a3d16ddde517c1b0fba7aa776822800f40"
 dependencies = [
 "aws-credential-types",
 "aws-smithy-async",
@@ -2230,9 +2196,9 @@ dependencies = [

 [[package]]
 name = "h2"
-version = "0.3.24"
+version = "0.3.26"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "bb2c4422095b67ee78da96fbb51a4cc413b3b25883c7717ff7ca1ab31022c9c9"
+checksum = "81fe527a889e1532da5c525686d96d4c2e74cdd345badf8dfef9f6b39dd5f5e8"
 dependencies = [
 "bytes",
 "fnv",
@@ -2392,9 +2358,9 @@ dependencies = [

 [[package]]
 name = "http"
-version = "1.0.0"
+version = "1.1.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "b32afd38673a8016f7c9ae69e5af41a58f81b1d31689040f2f1959594ce194ea"
+checksum = "21b9ddb458710bc376481b842f5da65cdf31522de232c1ca8146abce2a358258"
 dependencies = [
 "bytes",
 "fnv",
@@ -2494,7 +2460,7 @@ dependencies = [
 "hyper",
 "log",
 "rustls 0.21.9",
- "rustls-native-certs",
+ "rustls-native-certs 0.6.2",
 "tokio",
 "tokio-rustls 0.24.0",
 ]
@@ -2880,6 +2846,35 @@ version = "0.7.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "490cc448043f947bae3cbee9c203358d62dbee0db12107a74be5c30ccfd09771"

+[[package]]
+name = "measured"
+version = "0.0.13"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f246648d027839a34b420e27c7de1165ace96e19ef894985d0a6ff89a7840a9f"
+dependencies = [
+ "bytes",
+ "hashbrown 0.14.0",
+ "itoa",
+ "lasso",
+ "measured-derive",
+ "memchr",
+ "parking_lot 0.12.1",
+ "rustc-hash",
+ "ryu",
+]
+
+[[package]]
+name = "measured-derive"
+version = "0.0.13"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "edaa5cc22d99d5d6d7d99c3b5b5f7e7f8034c22f1b5d62a1adecd2ed005d9b80"
+dependencies = [
+ "heck",
+ "proc-macro2",
+ "quote",
+ "syn 2.0.52",
+]
+
 [[package]]
 name = "memchr"
 version = "2.6.4"
@@ -3402,9 +3397,9 @@ dependencies = [

 [[package]]
 name = "ordered-multimap"
-version = "0.7.1"
+version = "0.7.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "a4d6a8c22fc714f0c2373e6091bf6f5e9b37b1bc0b1184874b7e0a4e303d318f"
+checksum = "49203cdcae0030493bad186b28da2fa25645fa276a51b6fec8010d281e02ef79"
 dependencies = [
 "dlv-list",
 "hashbrown 0.14.0",
@@ -3548,6 +3543,7 @@ dependencies = [
 "strum_macros",
 "svg_fmt",
 "sync_wrapper",
+ "sysinfo",
 "tenant_size_model",
 "thiserror",
 "tokio",
@@ -3901,7 +3897,7 @@ dependencies = [
 [[package]]
 name = "postgres"
 version = "0.19.4"
-source = "git+https://github.com/neondatabase/rust-postgres.git?branch=neon#988d0ddb4184c408fa7fc1bd0ecca7993c02978f"
+source = "git+https://github.com/neondatabase/rust-postgres.git?branch=neon#20031d7a9ee1addeae6e0968e3899ae6bf01cee2"
 dependencies = [
 "bytes",
 "fallible-iterator",
@@ -3914,7 +3910,7 @@ dependencies = [
 [[package]]
 name = "postgres-native-tls"
 version = "0.5.0"
-source = "git+https://github.com/neondatabase/rust-postgres.git?branch=neon#988d0ddb4184c408fa7fc1bd0ecca7993c02978f"
+source = "git+https://github.com/neondatabase/rust-postgres.git?branch=neon#20031d7a9ee1addeae6e0968e3899ae6bf01cee2"
 dependencies = [
 "native-tls",
 "tokio",
@@ -3925,7 +3921,7 @@ dependencies = [
 [[package]]
 name = "postgres-protocol"
 version = "0.6.4"
-source = "git+https://github.com/neondatabase/rust-postgres.git?branch=neon#988d0ddb4184c408fa7fc1bd0ecca7993c02978f"
+source = "git+https://github.com/neondatabase/rust-postgres.git?branch=neon#20031d7a9ee1addeae6e0968e3899ae6bf01cee2"
 dependencies = [
 "base64 0.20.0",
 "byteorder",
@@ -3938,12 +3934,13 @@ dependencies = [
 "rand 0.8.5",
 "sha2",
 "stringprep",
+ "tokio",
 ]

 [[package]]
 name = "postgres-types"
 version = "0.2.4"
-source = "git+https://github.com/neondatabase/rust-postgres.git?branch=neon#988d0ddb4184c408fa7fc1bd0ecca7993c02978f"
+source = "git+https://github.com/neondatabase/rust-postgres.git?branch=neon#20031d7a9ee1addeae6e0968e3899ae6bf01cee2"
 dependencies = [
 "bytes",
 "fallible-iterator",
@@ -4164,7 +4161,12 @@ name = "proxy"
 version = "0.1.0"
 dependencies = [
 "anyhow",
+ "async-compression",
 "async-trait",
+ "aws-config",
+ "aws-sdk-iam",
+ "aws-sigv4",
+ "aws-types",
 "base64 0.13.1",
 "bstr",
 "bytes",
@@ -4175,6 +4177,7 @@ dependencies = [
 "consumption_metrics",
 "dashmap",
 "env_logger",
+ "fallible-iterator",
 "futures",
 "git-version",
 "hashbrown 0.13.2",
@@ -4182,6 +4185,7 @@ dependencies = [
 "hex",
 "hmac",
 "hostname",
+ "http 1.1.0",
 "humantime",
 "hyper",
 "hyper-tungstenite",
@@ -4225,6 +4229,7 @@ dependencies = [
 "smallvec",
 "smol_str",
 "socket2 0.5.5",
+ "subtle",
 "sync_wrapper",
 "task-local-extensions",
 "thiserror",
@@ -4396,9 +4401,9 @@ dependencies = [

 [[package]]
 name = "redis"
-version = "0.24.0"
+version = "0.25.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "c580d9cbbe1d1b479e8d67cf9daf6a62c957e6846048408b80b43ac3f6af84cd"
+checksum = "71d64e978fd98a0e6b105d066ba4889a7301fca65aeac850a877d8797343feeb"
 dependencies = [
 "async-trait",
 "bytes",
@@ -4407,15 +4412,15 @@ dependencies = [
 "itoa",
 "percent-encoding",
 "pin-project-lite",
- "rustls 0.21.9",
- "rustls-native-certs",
- "rustls-pemfile 1.0.2",
- "rustls-webpki 0.101.7",
+ "rustls 0.22.2",
+ "rustls-native-certs 0.7.0",
+ "rustls-pemfile 2.1.1",
+ "rustls-pki-types",
 "ryu",
 "sha1_smol",
- "socket2 0.4.9",
+ "socket2 0.5.5",
 "tokio",
- "tokio-rustls 0.24.0",
+ "tokio-rustls 0.25.0",
 "tokio-util",
 "url",
 ]
@@ -4844,6 +4849,19 @@ dependencies = [
 "security-framework",
 ]

+[[package]]
+name = "rustls-native-certs"
+version = "0.7.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8f1fb85efa936c42c6d5fc28d2629bb51e4b2f4b8a5211e297d599cc5a093792"
+dependencies = [
+ "openssl-probe",
+ "rustls-pemfile 2.1.1",
+ "rustls-pki-types",
+ "schannel",
+ "security-framework",
+]
+
 [[package]]
 name = "rustls-pemfile"
 version = "1.0.2"
@@ -5346,13 +5364,23 @@ checksum = "ae1a47186c03a32177042e55dbc5fd5aee900b8e0069a8d70fba96a9375cd012"

 [[package]]
 name = "sha2"
-version = "0.10.6"
+version = "0.10.8"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "82e6b795fe2e3b1e845bafcb27aa35405c4d47cdfc92af5fc8d3002f76cebdc0"
+checksum = "793db75ad2bcafc3ffa7c68b215fee268f537982cd901d132f89c6343f3a3dc8"
 dependencies = [
 "cfg-if",
 "cpufeatures",
 "digest",
+ "sha2-asm",
+]
+
+[[package]]
+name = "sha2-asm"
+version = "0.6.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f27ba7066011e3fb30d808b51affff34f0a66d3a03a58edd787c6e420e40e44e"
+dependencies = [
+ "cc",
 ]

 [[package]]
@@ -5556,6 +5584,65 @@ dependencies = [
 "workspace_hack",
 ]

+[[package]]
+name = "storage_controller"
+version = "0.1.0"
+dependencies = [
+ "anyhow",
+ "aws-config",
+ "bytes",
+ "camino",
+ "clap",
+ "control_plane",
+ "diesel",
+ "diesel_migrations",
+ "fail",
+ "futures",
+ "git-version",
+ "hex",
+ "humantime",
+ "hyper",
+ "itertools",
+ "lasso",
+ "measured",
+ "metrics",
+ "once_cell",
+ "pageserver_api",
+ "pageserver_client",
+ "postgres_connection",
+ "r2d2",
+ "reqwest",
+ "routerify",
+ "serde",
+ "serde_json",
+ "thiserror",
+ "tokio",
+ "tokio-util",
+ "tracing",
+ "utils",
+ "workspace_hack",
+]
+
+[[package]]
+name = "storcon_cli"
+version = "0.1.0"
+dependencies = [
+ "anyhow",
+ "clap",
+ "comfy-table",
+ "hyper",
+ "pageserver_api",
+ "pageserver_client",
+ "reqwest",
+ "serde",
+ "serde_json",
+ "thiserror",
+ "tokio",
+ "tracing",
+ "utils",
+ "workspace_hack",
+]
+
 [[package]]
 name = "stringprep"
 version = "0.1.2"
@@ -5712,23 +5799,23 @@ dependencies = [

 [[package]]
 name = "test-context"
-version = "0.1.4"
+version = "0.3.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "055831a02a4f5aa28fede67f2902014273eb8c21b958ac5ebbd59b71ef30dbc3"
+checksum = "6676ab8513edfd2601a108621103fdb45cac9098305ca25ec93f7023b06b05d9"
 dependencies = [
- "async-trait",
 "futures",
 "test-context-macros",
 ]

 [[package]]
 name = "test-context-macros"
-version = "0.1.4"
+version = "0.3.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "8901a55b0a7a06ebc4a674dcca925170da8e613fa3b163a1df804ed10afb154d"
+checksum = "78ea17a2dc368aeca6f554343ced1b1e31f76d63683fa8016e5844bd7a5144a1"
 dependencies = [
+ "proc-macro2",
 "quote",
- "syn 1.0.109",
+ "syn 2.0.52",
 ]

 [[package]]
@@ -5869,9 +5956,9 @@ checksum = "1f3ccbac311fea05f86f61904b462b55fb3df8837a366dfc601a0161d0532f20"

 [[package]]
 name = "tokio"
-version = "1.36.0"
+version = "1.37.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "61285f6515fa018fb2d1e46eb21223fff441ee8db5d0f1435e8ab4f5cdb80931"
+checksum = "1adbebffeca75fcfd058afa480fb6c0b81e165a0323f9c9d39c9697e37c46787"
 dependencies = [
 "backtrace",
 "bytes",
@@ -5935,7 +6022,7 @@ dependencies = [
 [[package]]
 name = "tokio-postgres"
 version = "0.7.7"
-source = "git+https://github.com/neondatabase/rust-postgres.git?branch=neon#988d0ddb4184c408fa7fc1bd0ecca7993c02978f"
+source = "git+https://github.com/neondatabase/rust-postgres.git?branch=neon#20031d7a9ee1addeae6e0968e3899ae6bf01cee2"
 dependencies = [
 "async-trait",
 "byteorder",
@@ -6101,7 +6188,7 @@ dependencies = [
 "percent-encoding",
 "pin-project",
 "prost",
- "rustls-native-certs",
+ "rustls-native-certs 0.6.2",
 "rustls-pemfile 1.0.2",
 "tokio",
 "tokio-rustls 0.24.0",
@@ -6468,6 +6555,7 @@ version = "0.1.0"
 dependencies = [
 "anyhow",
 "arc-swap",
+ "async-compression",
 "async-trait",
 "bincode",
 "byteorder",
@@ -6506,12 +6594,14 @@ dependencies = [
 "thiserror",
 "tokio",
 "tokio-stream",
+ "tokio-tar",
 "tokio-util",
 "tracing",
 "tracing-error",
 "tracing-subscriber",
 "url",
 "uuid",
+ "walkdir",
 "workspace_hack",
 ]

@@ -6983,7 +7073,6 @@ dependencies = [
 "aws-sigv4",
 "aws-smithy-async",
 "aws-smithy-http",
- "aws-smithy-runtime-api",
 "aws-smithy-types",
 "axum",
 "base64 0.21.1",
@@ -7029,6 +7118,7 @@ dependencies = [
 "scopeguard",
 "serde",
 "serde_json",
+ "sha2",
 "smallvec",
 "subtle",
 "syn 1.0.109",
@@ -3,7 +3,7 @@ resolver = "2"
 members = [
    "compute_tools",
    "control_plane",
-    "control_plane/attachment_service",
+    "control_plane/storcon_cli",
    "pageserver",
    "pageserver/compaction",
    "pageserver/ctl",
@@ -12,6 +12,7 @@ members = [
    "proxy",
    "safekeeper",
    "storage_broker",
+    "storage_controller",
    "s3_scrubber",
    "workspace_hack",
    "trace",
@@ -52,10 +53,12 @@ async-stream = "0.3"
 async-trait = "0.1"
 aws-config = { version = "1.1.4", default-features = false, features=["rustls"] }
 aws-sdk-s3 = "1.14"
-aws-sdk-secretsmanager = { version = "1.14.0" }
+aws-sdk-iam = "1.15.0"
 aws-smithy-async = { version = "1.1.4", default-features = false, features=["rt-tokio"] }
 aws-smithy-types = "1.1.4"
 aws-credential-types = "1.1.4"
+aws-sigv4 = { version = "1.2.0", features = ["sign-http"] }
+aws-types = "1.1.7"
 axum = { version = "0.6.20", features = ["ws"] }
 base64 = "0.13.0"
 bincode = "1.3"
@@ -76,6 +79,7 @@ either = "1.8"
 enum-map = "2.4.2"
 enumset = "1.0.12"
 fail = "0.5.0"
+fallible-iterator = "0.2"
 fs2 = "0.4.3"
 futures = "0.3"
 futures-core = "0.3"
@@ -88,6 +92,7 @@ hex = "0.4"
 hex-literal = "0.4"
 hmac = "0.12.1"
 hostname = "0.3.1"
+http = {version = "1.1.0", features = ["std"]}
 http-types = { version = "2", default-features = false }
 humantime = "2.1"
 humantime-serde = "1.1.1"
@@ -101,6 +106,7 @@ lasso = "0.7"
 leaky-bucket = "1.0.1"
 libc = "0.2"
 md5 = "0.7.0"
+measured = { version = "0.0.13", features=["default", "lasso"] }
 memoffset = "0.8"
 native-tls = "0.2"
 nix = { version = "0.27", features = ["fs", "process", "socket", "signal", "poll"] }
@@ -120,7 +126,7 @@ procfs = "0.14"
 prometheus = {version = "0.13", default_features=false, features = ["process"]} # removes protobuf dependency
 prost = "0.11"
 rand = "0.8"
-redis = { version = "0.24.0", features = ["tokio-rustls-comp", "keep-alive"] }
+redis = { version = "0.25.2", features = ["tokio-rustls-comp", "keep-alive"] }
 regex = "1.10.2"
 reqwest = { version = "0.11", default-features = false, features = ["rustls-tls"] }
 reqwest-tracing = { version = "0.4.7", features = ["opentelemetry_0_20"] }
@@ -148,11 +154,12 @@ smol_str = { version = "0.2.0", features = ["serde"] }
 socket2 = "0.5"
 strum = "0.24"
 strum_macros = "0.24"
+"subtle"  = "2.5.0"
 svg_fmt = "0.4.1"
 sync_wrapper = "0.1.2"
 tar = "0.4"
 task-local-extensions = "0.1.4"
-test-context = "0.1"
+test-context = "0.3"
 thiserror = "1.0"
 tikv-jemallocator = "0.5"
 tikv-jemalloc-ctl = "0.5"
@@ -135,7 +135,7 @@ WORKDIR /home/nonroot

 # Rust
 # Please keep the version of llvm (installed above) in sync with rust llvm (`rustc --version --verbose | grep LLVM`)
-ENV RUSTC_VERSION=1.76.0
+ENV RUSTC_VERSION=1.77.0
 ENV RUSTUP_HOME="/home/nonroot/.rustup"
 ENV PATH="/home/nonroot/.cargo/bin:${PATH}"
 RUN curl -sSO https://static.rust-lang.org/rustup/dist/$(uname -m)-unknown-linux-gnu/rustup-init && whoami && \
@@ -149,7 +149,7 @@ RUN curl -sSO https://static.rust-lang.org/rustup/dist/$(uname -m)-unknown-linux
    cargo install --git https://github.com/paritytech/cachepot && \
    cargo install rustfilt && \
    cargo install cargo-hakari && \
-    cargo install cargo-deny && \
+    cargo install cargo-deny --locked && \
    cargo install cargo-hack && \
    cargo install cargo-nextest && \
    rm -rf /home/nonroot/.cargo/registry && \
@@ -944,6 +944,9 @@ RUN mkdir /var/db && useradd -m -d /var/db/postgres postgres && \
 COPY --from=postgres-cleanup-layer --chown=postgres /usr/local/pgsql /usr/local
 COPY --from=compute-tools --chown=postgres /home/nonroot/target/release-line-debug-size-lto/compute_ctl /usr/local/bin/compute_ctl

+# Create remote extension download directory
+RUN mkdir /usr/local/download_extensions && chown -R postgres:postgres /usr/local/download_extensions
+
 # Install:
 # libreadline8 for psql
 # libicu67, locales for collations (including ICU and plpgsql_check)
@@ -32,6 +32,29 @@ compute_ctl -D /var/db/postgres/compute \
            -b /usr/local/bin/postgres
 ```

+## State Diagram
+
+Computes can be in various states. Below is a diagram that details how a
+compute moves between states.
+
+```mermaid
+%% https://mermaid.js.org/syntax/stateDiagram.html
+stateDiagram-v2
+  [*] --> Empty : Compute spawned
+  Empty --> ConfigurationPending : Waiting for compute spec
+  ConfigurationPending --> Configuration : Received compute spec
+  Configuration --> Failed : Failed to configure the compute
+  Configuration --> Running : Compute has been configured
+  Empty --> Init : Compute spec is immediately available
+  Empty --> TerminationPending : Requested termination
+  Init --> Failed : Failed to start Postgres
+  Init --> Running : Started Postgres
+  Running --> TerminationPending : Requested termination
+  TerminationPending --> Terminated : Terminated compute
+  Failed --> [*] : Compute exited
+  Terminated --> [*] : Compute exited
+```
+
 ## Tests

 Cargo formatter:
@@ -1262,10 +1262,12 @@ LIMIT 100",
        .await
        .map_err(DownloadError::Other);

-        self.ext_download_progress
-            .write()
-            .expect("bad lock")
-            .insert(ext_archive_name.to_string(), (download_start, true));
+        if download_size.is_ok() {
+            self.ext_download_progress
+                .write()
+                .expect("bad lock")
+                .insert(ext_archive_name.to_string(), (download_start, true));
+        }

        download_size
    }
@@ -17,6 +17,7 @@ pub fn line_in_file(path: &Path, line: &str) -> Result<bool> {
        .write(true)
        .create(true)
        .append(false)
+        .truncate(false)
        .open(path)?;
    let buf = io::BufReader::new(&file);
    let mut count: usize = 0;
@@ -302,9 +302,9 @@ pub fn handle_roles(spec: &ComputeSpec, client: &mut Client) -> Result<()> {
            RoleAction::Create => {
                // This branch only runs when roles are created through the console, so it is
                // safe to add more permissions here. BYPASSRLS and REPLICATION are inherited
-                // from neon_superuser. (NOTE: REPLICATION has been removed from here for now).
+                // from neon_superuser.
                let mut query: String = format!(
-                    "CREATE ROLE {} INHERIT CREATEROLE CREATEDB BYPASSRLS IN ROLE neon_superuser",
+                    "CREATE ROLE {} INHERIT CREATEROLE CREATEDB BYPASSRLS REPLICATION IN ROLE neon_superuser",
                    name.pg_quote()
                );
                info!("running role create query: '{}'", &query);
@@ -743,21 +743,24 @@ pub fn handle_extension_neon(client: &mut Client) -> Result<()> {
    // which may happen in two cases:
    // - extension was just installed
    // - extension was already installed and is up to date
-    // DISABLED due to compute node unpinning epic
-    // let query = "ALTER EXTENSION neon UPDATE";
-    // info!("update neon extension version with query: {}", query);
-    // client.simple_query(query)?;
+    let query = "ALTER EXTENSION neon UPDATE";
+    info!("update neon extension version with query: {}", query);
+    if let Err(e) = client.simple_query(query) {
+        error!(
+            "failed to upgrade neon extension during `handle_extension_neon`: {}",
+            e
+        );
+    }

    Ok(())
 }

 #[instrument(skip_all)]
-pub fn handle_neon_extension_upgrade(_client: &mut Client) -> Result<()> {
-    info!("handle neon extension upgrade (not really)");
-    // DISABLED due to compute node unpinning epic
-    // let query = "ALTER EXTENSION neon UPDATE";
-    // info!("update neon extension version with query: {}", query);
-    // client.simple_query(query)?;
+pub fn handle_neon_extension_upgrade(client: &mut Client) -> Result<()> {
+    info!("handle neon extension upgrade");
+    let query = "ALTER EXTENSION neon UPDATE";
+    info!("update neon extension version with query: {}", query);
+    client.simple_query(query)?;

    Ok(())
 }
@@ -806,19 +809,8 @@ $$;"#,
        "",
        "",
        "",
+        "",
        // Add new migrations below.
-        r#"
-DO $$
-DECLARE
-    role_name TEXT;
-BEGIN
-    FOR role_name IN SELECT rolname FROM pg_roles WHERE rolreplication IS TRUE
-    LOOP
-        RAISE NOTICE 'EXECUTING ALTER ROLE % NOREPLICATION', quote_ident(role_name);
-        EXECUTE 'ALTER ROLE ' || quote_ident(role_name) || ' NOREPLICATION';
-    END LOOP;
-END
-$$;"#,
    ];

    let mut query = "CREATE SCHEMA IF NOT EXISTS neon_migration";
@@ -1,32 +0,0 @@
-use metrics::{register_int_counter, register_int_counter_vec, IntCounter, IntCounterVec};
-use once_cell::sync::Lazy;
-
-pub(crate) struct ReconcilerMetrics {
-    pub(crate) spawned: IntCounter,
-    pub(crate) complete: IntCounterVec,
-}
-
-impl ReconcilerMetrics {
-    // Labels used on [`Self::complete`]
-    pub(crate) const SUCCESS: &'static str = "ok";
-    pub(crate) const ERROR: &'static str = "success";
-    pub(crate) const CANCEL: &'static str = "cancel";
-}
-
-pub(crate) static RECONCILER: Lazy<ReconcilerMetrics> = Lazy::new(|| ReconcilerMetrics {
-    spawned: register_int_counter!(
-        "storage_controller_reconcile_spawn",
-        "Count of how many times we spawn a reconcile task",
-    )
-    .expect("failed to define a metric"),
-    complete: register_int_counter_vec!(
-        "storage_controller_reconcile_complete",
-        "Reconciler tasks completed, broken down by success/failure/cancelled",
-        &["status"],
-    )
-    .expect("failed to define a metric"),
-});
-
-pub fn preinitialize_metrics() {
-    Lazy::force(&RECONCILER);
-}
@@ -294,7 +294,7 @@ where
    //      is in state 'taken' but the thread that would unlock it is
    //      not there.
    //   2. A rust object that represented some external resource in the
-    //      parent now got implicitly copied by the the fork, even though
+    //      parent now got implicitly copied by the fork, even though
    //      the object's type is not `Copy`. The parent program may use
    //      non-copyability as way to enforce unique ownership of an
    //      external resource in the typesystem. The fork breaks that
@@ -14,9 +14,7 @@ use control_plane::pageserver::{PageServerNode, PAGESERVER_REMOTE_STORAGE_DIR};
 use control_plane::safekeeper::SafekeeperNode;
 use control_plane::storage_controller::StorageController;
 use control_plane::{broker, local_env};
-use pageserver_api::controller_api::{
-    NodeAvailability, NodeConfigureRequest, NodeSchedulingPolicy, PlacementPolicy,
-};
+use pageserver_api::controller_api::PlacementPolicy;
 use pageserver_api::models::{
    ShardParameters, TenantCreateRequest, TimelineCreateRequest, TimelineInfo,
 };
@@ -437,7 +435,7 @@ async fn handle_tenant(

            let placement_policy = match create_match.get_one::<String>("placement-policy") {
                Some(s) if !s.is_empty() => serde_json::from_str::<PlacementPolicy>(s)?,
-                _ => PlacementPolicy::Single,
+                _ => PlacementPolicy::Attached(0),
            };

            let tenant_conf = PageServerNode::parse_config(tenant_conf)?;
@@ -523,88 +521,6 @@ async fn handle_tenant(
                .with_context(|| format!("Tenant config failed for tenant with id {tenant_id}"))?;
            println!("tenant {tenant_id} successfully configured on the pageserver");
        }
-        Some(("migrate", matches)) => {
-            let tenant_shard_id = get_tenant_shard_id(matches, env)?;
-            let new_pageserver = get_pageserver(env, matches)?;
-            let new_pageserver_id = new_pageserver.conf.id;
-
-            let storage_controller = StorageController::from_env(env);
-            storage_controller
-                .tenant_migrate(tenant_shard_id, new_pageserver_id)
-                .await?;
-
-            println!("tenant {tenant_shard_id} migrated to {}", new_pageserver_id);
-        }
-        Some(("status", matches)) => {
-            let tenant_id = get_tenant_id(matches, env)?;
-
-            let mut shard_table = comfy_table::Table::new();
-            shard_table.set_header(["Shard", "Pageserver", "Physical Size"]);
-
-            let mut tenant_synthetic_size = None;
-
-            let storage_controller = StorageController::from_env(env);
-            for shard in storage_controller.tenant_locate(tenant_id).await?.shards {
-                let pageserver =
-                    PageServerNode::from_env(env, env.get_pageserver_conf(shard.node_id)?);
-
-                let size = pageserver
-                    .http_client
-                    .tenant_details(shard.shard_id)
-                    .await?
-                    .tenant_info
-                    .current_physical_size
-                    .unwrap();
-
-                shard_table.add_row([
-                    format!("{}", shard.shard_id.shard_slug()),
-                    format!("{}", shard.node_id.0),
-                    format!("{} MiB", size / (1024 * 1024)),
-                ]);
-
-                if shard.shard_id.is_zero() {
-                    tenant_synthetic_size =
-                        Some(pageserver.tenant_synthetic_size(shard.shard_id).await?);
-                }
-            }
-
-            let Some(synthetic_size) = tenant_synthetic_size else {
-                bail!("Shard 0 not found")
-            };
-
-            let mut tenant_table = comfy_table::Table::new();
-            tenant_table.add_row(["Tenant ID".to_string(), tenant_id.to_string()]);
-            tenant_table.add_row([
-                "Synthetic size".to_string(),
-                format!("{} MiB", synthetic_size.size.unwrap_or(0) / (1024 * 1024)),
-            ]);
-
-            println!("{tenant_table}");
-            println!("{shard_table}");
-        }
-        Some(("shard-split", matches)) => {
-            let tenant_id = get_tenant_id(matches, env)?;
-            let shard_count: u8 = matches.get_one::<u8>("shard-count").cloned().unwrap_or(0);
-            let shard_stripe_size: Option<ShardStripeSize> = matches
-                .get_one::<Option<ShardStripeSize>>("shard-stripe-size")
-                .cloned()
-                .unwrap();
-
-            let storage_controller = StorageController::from_env(env);
-            let result = storage_controller
-                .tenant_split(tenant_id, shard_count, shard_stripe_size)
-                .await?;
-            println!(
-                "Split tenant {} into shards {}",
-                tenant_id,
-                result
-                    .new_shards
-                    .iter()
-                    .map(|s| format!("{:?}", s))
-                    .collect::<Vec<_>>()
-                    .join(",")
-            );
-        }

        Some((sub_name, _)) => bail!("Unexpected tenant subcommand '{}'", sub_name),
        None => bail!("no tenant subcommand provided"),
@@ -1142,21 +1058,6 @@ async fn handle_pageserver(sub_match: &ArgMatches, env: &local_env::LocalEnv) ->
            }
        }

-        Some(("set-state", subcommand_args)) => {
-            let pageserver = get_pageserver(env, subcommand_args)?;
-            let scheduling = subcommand_args.get_one("scheduling");
-            let availability = subcommand_args.get_one("availability");
-
-            let storage_controller = StorageController::from_env(env);
-            storage_controller
-                .node_configure(NodeConfigureRequest {
-                    node_id: pageserver.conf.id,
-                    scheduling: scheduling.cloned(),
-                    availability: availability.cloned(),
-                })
-                .await?;
-        }
-
        Some(("status", subcommand_args)) => {
            match get_pageserver(env, subcommand_args)?.check_status().await {
                Ok(_) => println!("Page server is up and running"),
@@ -1578,19 +1479,6 @@ fn cli() -> Command {
            .subcommand(Command::new("config")
                .arg(tenant_id_arg.clone())
                .arg(Arg::new("config").short('c').num_args(1).action(ArgAction::Append).required(false)))
-            .subcommand(Command::new("migrate")
-                .about("Migrate a tenant from one pageserver to another")
-                .arg(tenant_id_arg.clone())
-                .arg(pageserver_id_arg.clone()))
-            .subcommand(Command::new("status")
-                .about("Human readable summary of the tenant's shards and attachment locations")
-                .arg(tenant_id_arg.clone()))
-            .subcommand(Command::new("shard-split")
-                .about("Increase the number of shards in the tenant")
-                .arg(tenant_id_arg.clone())
-                .arg(Arg::new("shard-count").value_parser(value_parser!(u8)).long("shard-count").action(ArgAction::Set).help("Number of shards in the new tenant (default 1)"))
-                .arg(Arg::new("shard-stripe-size").value_parser(value_parser!(u32)).long("shard-stripe-size").action(ArgAction::Set).help("Sharding stripe size in pages"))
-                )
        )
        .subcommand(
            Command::new("pageserver")
@@ -1610,12 +1498,6 @@ fn cli() -> Command {
                    .about("Restart local pageserver")
                    .arg(pageserver_config_args.clone())
                )
-                .subcommand(Command::new("set-state")
-                    .arg(Arg::new("availability").value_parser(value_parser!(NodeAvailability)).long("availability").action(ArgAction::Set).help("Availability state: offline,active"))
-                    .arg(Arg::new("scheduling").value_parser(value_parser!(NodeSchedulingPolicy)).long("scheduling").action(ArgAction::Set).help("Scheduling state: draining,pause,filling,active"))
-                    .about("Set scheduling or availability state of pageserver node")
-                    .arg(pageserver_config_args.clone())
-                )
        )
        .subcommand(
            Command::new("storage_controller")
@@ -12,7 +12,7 @@
 //!
 //! The endpoint is managed by the `compute_ctl` binary. When an endpoint is
 //! started, we launch `compute_ctl` It synchronizes the safekeepers, downloads
-//! the basebackup from the pageserver to initialize the the data directory, and
+//! the basebackup from the pageserver to initialize the data directory, and
 //! finally launches the PostgreSQL process. It watches the PostgreSQL process
 //! until it exits.
 //!
@@ -127,8 +127,8 @@ pub struct PageServerConf {
    pub pg_auth_type: AuthType,
    pub http_auth_type: AuthType,

-    pub(crate) virtual_file_io_engine: String,
-    pub(crate) get_vectored_impl: String,
+    pub(crate) virtual_file_io_engine: Option<String>,
+    pub(crate) get_vectored_impl: Option<String>,
 }

 impl Default for PageServerConf {
@@ -139,9 +139,8 @@ impl Default for PageServerConf {
            listen_http_addr: String::new(),
            pg_auth_type: AuthType::Trust,
            http_auth_type: AuthType::Trust,
-            // FIXME: use the ones exposed by pageserver crate
-            virtual_file_io_engine: "tokio-epoll-uring".to_owned(),
-            get_vectored_impl: "sequential".to_owned(),
+            virtual_file_io_engine: None,
+            get_vectored_impl: None,
        }
    }
 }
@@ -101,8 +101,16 @@ impl PageServerNode {

        let pg_auth_type_param = format!("pg_auth_type='{}'", pg_auth_type);
        let listen_pg_addr_param = format!("listen_pg_addr='{}'", listen_pg_addr);
-        let virtual_file_io_engine = format!("virtual_file_io_engine='{virtual_file_io_engine}'");
-        let get_vectored_impl = format!("get_vectored_impl='{get_vectored_impl}'");
+        let virtual_file_io_engine = if let Some(virtual_file_io_engine) = virtual_file_io_engine {
+            format!("virtual_file_io_engine='{virtual_file_io_engine}'")
+        } else {
+            String::new()
+        };
+        let get_vectored_impl = if let Some(get_vectored_impl) = get_vectored_impl {
+            format!("get_vectored_impl='{get_vectored_impl}'")
+        } else {
+            String::new()
+        };

        let broker_endpoint_param = format!("broker_endpoint='{}'", self.env.broker.client_url());

@@ -381,6 +389,10 @@ impl PageServerNode {
                .remove("image_creation_threshold")
                .map(|x| x.parse::<usize>())
                .transpose()?,
+            image_layer_creation_check_threshold: settings
+                .remove("image_layer_creation_check_threshold")
+                .map(|x| x.parse::<u8>())
+                .transpose()?,
            pitr_interval: settings.remove("pitr_interval").map(|x| x.to_string()),
            walreceiver_connect_timeout: settings
                .remove("walreceiver_connect_timeout")
@@ -493,6 +505,12 @@ impl PageServerNode {
                    .map(|x| x.parse::<usize>())
                    .transpose()
                    .context("Failed to parse 'image_creation_threshold' as non zero integer")?,
+                image_layer_creation_check_threshold: settings
+                    .remove("image_layer_creation_check_threshold")
+                    .map(|x| x.parse::<u8>())
+                    .transpose()
+                    .context("Failed to parse 'image_creation_check_threshold' as integer")?,
+
                pitr_interval: settings.remove("pitr_interval").map(|x| x.to_string()),
                walreceiver_connect_timeout: settings
                    .remove("walreceiver_connect_timeout")
@@ -279,6 +279,7 @@ impl StorageController {
            &self.listen,
            "-p",
            self.path.as_ref(),
+            "--dev",
            "--database-url",
            &database_url,
            "--max-unavailable-interval",
@@ -475,7 +476,7 @@ impl StorageController {
    pub async fn tenant_locate(&self, tenant_id: TenantId) -> anyhow::Result<TenantLocateResponse> {
        self.dispatch::<(), _>(
            Method::GET,
-            format!("control/v1/tenant/{tenant_id}/locate"),
+            format!("debug/v1/tenant/{tenant_id}/locate"),
            None,
        )
        .await
@@ -0,0 +1,23 @@
+[package]
+name = "storcon_cli"
+version = "0.1.0"
+edition.workspace = true
+license.workspace = true
+
+
+[dependencies]
+anyhow.workspace = true
+clap.workspace = true
+comfy-table.workspace = true
+hyper.workspace = true
+pageserver_api.workspace = true
+pageserver_client.workspace = true
+reqwest.workspace = true
+serde.workspace = true
+serde_json = { workspace = true, features = ["raw_value"] }
+thiserror.workspace = true
+tokio.workspace = true
+tracing.workspace = true
+utils.workspace = true
+workspace_hack.workspace = true
+
@@ -0,0 +1,587 @@
+use std::{collections::HashMap, str::FromStr};
+
+use clap::{Parser, Subcommand};
+use hyper::Method;
+use pageserver_api::{
+    controller_api::{
+        NodeAvailabilityWrapper, NodeDescribeResponse, ShardSchedulingPolicy,
+        TenantDescribeResponse, TenantPolicyRequest,
+    },
+    models::{
+        ShardParameters, TenantConfig, TenantConfigRequest, TenantCreateRequest,
+        TenantShardSplitRequest, TenantShardSplitResponse,
+    },
+    shard::{ShardStripeSize, TenantShardId},
+};
+use pageserver_client::mgmt_api::{self, ResponseErrorMessageExt};
+use reqwest::Url;
+use serde::{de::DeserializeOwned, Serialize};
+use utils::id::{NodeId, TenantId};
+
+use pageserver_api::controller_api::{
+    NodeConfigureRequest, NodeRegisterRequest, NodeSchedulingPolicy, PlacementPolicy,
+    TenantLocateResponse, TenantShardMigrateRequest, TenantShardMigrateResponse,
+};
+
+#[derive(Subcommand, Debug)]
+enum Command {
+    /// Register a pageserver with the storage controller.  This shouldn't usually be necessary,
+    /// since pageservers auto-register when they start up
+    NodeRegister {
+        #[arg(long)]
+        node_id: NodeId,
+
+        #[arg(long)]
+        listen_pg_addr: String,
+        #[arg(long)]
+        listen_pg_port: u16,
+
+        #[arg(long)]
+        listen_http_addr: String,
+        #[arg(long)]
+        listen_http_port: u16,
+    },
+
+    /// Modify a node's configuration in the storage controller
+    NodeConfigure {
+        #[arg(long)]
+        node_id: NodeId,
+
+        /// Availability is usually auto-detected based on heartbeats.  Set 'offline' here to
+        /// manually mark a node offline
+        #[arg(long)]
+        availability: Option<NodeAvailabilityArg>,
+        /// Scheduling policy controls whether tenant shards may be scheduled onto this node.
+        #[arg(long)]
+        scheduling: Option<NodeSchedulingPolicy>,
+    },
+    /// Modify a tenant's policies in the storage controller
+    TenantPolicy {
+        #[arg(long)]
+        tenant_id: TenantId,
+        /// Placement policy controls whether a tenant is `detached`, has only a secondary location (`secondary`),
+        /// or is in the normal attached state with N secondary locations (`attached:N`)
+        #[arg(long)]
+        placement: Option<PlacementPolicyArg>,
+        /// Scheduling policy enables pausing the controller's scheduling activity involving this tenant.  `active` is normal,
+        /// `essential` disables optimization scheduling changes, `pause` disables all scheduling changes, and `stop` prevents
+        /// all reconciliation activity including for scheduling changes already made.  `pause` and `stop` can make a tenant
+        /// unavailable, and are only for use in emergencies.
+        #[arg(long)]
+        scheduling: Option<ShardSchedulingPolicyArg>,
+    },
+    /// List nodes known to the storage controller
+    Nodes {},
+    /// List tenants known to the storage controller
+    Tenants {},
+    /// Create a new tenant in the storage controller, and by extension on pageservers.
+    TenantCreate {
+        #[arg(long)]
+        tenant_id: TenantId,
+    },
+    /// Delete a tenant in the storage controller, and by extension on pageservers.
+    TenantDelete {
+        #[arg(long)]
+        tenant_id: TenantId,
+    },
+    /// Split an existing tenant into a higher number of shards than its current shard count.
+    TenantShardSplit {
+        #[arg(long)]
+        tenant_id: TenantId,
+        #[arg(long)]
+        shard_count: u8,
+        /// Optional, in 8kiB pages.  e.g. set 2048 for 16MB stripes.
+        #[arg(long)]
+        stripe_size: Option<u32>,
+    },
+    /// Migrate the attached location for a tenant shard to a specific pageserver.
+    TenantShardMigrate {
+        #[arg(long)]
+        tenant_shard_id: TenantShardId,
+        #[arg(long)]
+        node: NodeId,
+    },
+    /// Modify the pageserver tenant configuration of a tenant: this is the configuration structure
+    /// that is passed through to pageservers, and does not affect storage controller behavior.
+    TenantConfig {
+        #[arg(long)]
+        tenant_id: TenantId,
+        #[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)]
+        tenant_id: TenantId,
+    },
+}
+
+#[derive(Parser)]
+#[command(
+    author,
+    version,
+    about,
+    long_about = "CLI for Storage Controller Support/Debug"
+)]
+#[command(arg_required_else_help(true))]
+struct Cli {
+    #[arg(long)]
+    /// URL to storage controller.  e.g. http://127.0.0.1:1234 when using `neon_local`
+    api: Url,
+
+    #[arg(long)]
+    /// JWT token for authenticating with storage controller.  Depending on the API used, this
+    /// should have either `pageserverapi` or `admin` scopes: for convenience, you should mint
+    /// a token with both scopes to use with this tool.
+    jwt: Option<String>,
+
+    #[command(subcommand)]
+    command: Command,
+}
+
+#[derive(Debug, Clone)]
+struct PlacementPolicyArg(PlacementPolicy);
+
+impl FromStr for PlacementPolicyArg {
+    type Err = anyhow::Error;
+
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        match s {
+            "detached" => Ok(Self(PlacementPolicy::Detached)),
+            "secondary" => Ok(Self(PlacementPolicy::Secondary)),
+            _ if s.starts_with("attached:") => {
+                let mut splitter = s.split(':');
+                let _prefix = splitter.next().unwrap();
+                match splitter.next().and_then(|s| s.parse::<usize>().ok()) {
+                    Some(n) => Ok(Self(PlacementPolicy::Attached(n))),
+                    None => Err(anyhow::anyhow!(
+                        "Invalid format '{s}', a valid example is 'attached:1'"
+                    )),
+                }
+            }
+            _ => Err(anyhow::anyhow!(
+                "Unknown placement policy '{s}', try detached,secondary,attached:<n>"
+            )),
+        }
+    }
+}
+
+#[derive(Debug, Clone)]
+struct ShardSchedulingPolicyArg(ShardSchedulingPolicy);
+
+impl FromStr for ShardSchedulingPolicyArg {
+    type Err = anyhow::Error;
+
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        match s {
+            "active" => Ok(Self(ShardSchedulingPolicy::Active)),
+            "essential" => Ok(Self(ShardSchedulingPolicy::Essential)),
+            "pause" => Ok(Self(ShardSchedulingPolicy::Pause)),
+            "stop" => Ok(Self(ShardSchedulingPolicy::Stop)),
+            _ => Err(anyhow::anyhow!(
+                "Unknown scheduling policy '{s}', try active,essential,pause,stop"
+            )),
+        }
+    }
+}
+
+#[derive(Debug, Clone)]
+struct NodeAvailabilityArg(NodeAvailabilityWrapper);
+
+impl FromStr for NodeAvailabilityArg {
+    type Err = anyhow::Error;
+
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        match s {
+            "active" => Ok(Self(NodeAvailabilityWrapper::Active)),
+            "offline" => Ok(Self(NodeAvailabilityWrapper::Offline)),
+            _ => Err(anyhow::anyhow!("Unknown availability state '{s}'")),
+        }
+    }
+}
+
+struct Client {
+    base_url: Url,
+    jwt_token: Option<String>,
+    client: reqwest::Client,
+}
+
+impl Client {
+    fn new(base_url: Url, jwt_token: Option<String>) -> Self {
+        Self {
+            base_url,
+            jwt_token,
+            client: reqwest::ClientBuilder::new()
+                .build()
+                .expect("Failed to construct http client"),
+        }
+    }
+
+    /// Simple HTTP request wrapper for calling into storage controller
+    async fn dispatch<RQ, RS>(
+        &self,
+        method: hyper::Method,
+        path: String,
+        body: Option<RQ>,
+    ) -> mgmt_api::Result<RS>
+    where
+        RQ: Serialize + Sized,
+        RS: DeserializeOwned + Sized,
+    {
+        // The configured URL has the /upcall path prefix for pageservers to use: we will strip that out
+        // for general purpose API access.
+        let url = Url::from_str(&format!(
+            "http://{}:{}/{path}",
+            self.base_url.host_str().unwrap(),
+            self.base_url.port().unwrap()
+        ))
+        .unwrap();
+
+        let mut builder = self.client.request(method, url);
+        if let Some(body) = body {
+            builder = builder.json(&body)
+        }
+        if let Some(jwt_token) = &self.jwt_token {
+            builder = builder.header(
+                reqwest::header::AUTHORIZATION,
+                format!("Bearer {jwt_token}"),
+            );
+        }
+
+        let response = builder.send().await.map_err(mgmt_api::Error::ReceiveBody)?;
+        let response = response.error_from_body().await?;
+
+        response
+            .json()
+            .await
+            .map_err(pageserver_client::mgmt_api::Error::ReceiveBody)
+    }
+}
+
+#[tokio::main]
+async fn main() -> anyhow::Result<()> {
+    let cli = Cli::parse();
+
+    let storcon_client = Client::new(cli.api.clone(), cli.jwt.clone());
+
+    let mut trimmed = cli.api.to_string();
+    trimmed.pop();
+    let vps_client = mgmt_api::Client::new(trimmed, cli.jwt.as_deref());
+
+    match cli.command {
+        Command::NodeRegister {
+            node_id,
+            listen_pg_addr,
+            listen_pg_port,
+            listen_http_addr,
+            listen_http_port,
+        } => {
+            storcon_client
+                .dispatch::<_, ()>(
+                    Method::POST,
+                    "control/v1/node".to_string(),
+                    Some(NodeRegisterRequest {
+                        node_id,
+                        listen_pg_addr,
+                        listen_pg_port,
+                        listen_http_addr,
+                        listen_http_port,
+                    }),
+                )
+                .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(),
+                })
+                .await?;
+        }
+        Command::TenantDelete { tenant_id } => {
+            let status = vps_client
+                .tenant_delete(TenantShardId::unsharded(tenant_id))
+                .await?;
+            tracing::info!("Delete status: {}", status);
+        }
+        Command::Nodes {} => {
+            let resp = storcon_client
+                .dispatch::<(), Vec<NodeDescribeResponse>>(
+                    Method::GET,
+                    "control/v1/node".to_string(),
+                    None,
+                )
+                .await?;
+            let mut table = comfy_table::Table::new();
+            table.set_header(["Id", "Hostname", "Scheduling", "Availability"]);
+            for node in resp {
+                table.add_row([
+                    format!("{}", node.id),
+                    node.listen_http_addr,
+                    format!("{:?}", node.scheduling),
+                    format!("{:?}", node.availability),
+                ]);
+            }
+            println!("{table}");
+        }
+        Command::NodeConfigure {
+            node_id,
+            availability,
+            scheduling,
+        } => {
+            let req = NodeConfigureRequest {
+                node_id,
+                availability: availability.map(|a| a.0),
+                scheduling,
+            };
+            storcon_client
+                .dispatch::<_, ()>(
+                    Method::PUT,
+                    format!("control/v1/node/{node_id}/config"),
+                    Some(req),
+                )
+                .await?;
+        }
+        Command::Tenants {} => {
+            let resp = storcon_client
+                .dispatch::<(), Vec<TenantDescribeResponse>>(
+                    Method::GET,
+                    "control/v1/tenant".to_string(),
+                    None,
+                )
+                .await?;
+            let mut table = comfy_table::Table::new();
+            table.set_header([
+                "TenantId",
+                "ShardCount",
+                "StripeSize",
+                "Placement",
+                "Scheduling",
+            ]);
+            for tenant in resp {
+                let shard_zero = tenant.shards.into_iter().next().unwrap();
+                table.add_row([
+                    format!("{}", tenant.tenant_id),
+                    format!("{}", shard_zero.tenant_shard_id.shard_count.literal()),
+                    format!("{:?}", tenant.stripe_size),
+                    format!("{:?}", tenant.policy),
+                    format!("{:?}", shard_zero.scheduling_policy),
+                ]);
+            }
+
+            println!("{table}");
+        }
+        Command::TenantPolicy {
+            tenant_id,
+            placement,
+            scheduling,
+        } => {
+            let req = TenantPolicyRequest {
+                scheduling: scheduling.map(|s| s.0),
+                placement: placement.map(|p| p.0),
+            };
+            storcon_client
+                .dispatch::<_, ()>(
+                    Method::PUT,
+                    format!("control/v1/tenant/{tenant_id}/policy"),
+                    Some(req),
+                )
+                .await?;
+        }
+        Command::TenantShardSplit {
+            tenant_id,
+            shard_count,
+            stripe_size,
+        } => {
+            let req = TenantShardSplitRequest {
+                new_shard_count: shard_count,
+                new_stripe_size: stripe_size.map(ShardStripeSize),
+            };
+
+            let response = storcon_client
+                .dispatch::<TenantShardSplitRequest, TenantShardSplitResponse>(
+                    Method::PUT,
+                    format!("control/v1/tenant/{tenant_id}/shard_split"),
+                    Some(req),
+                )
+                .await?;
+            println!(
+                "Split tenant {} into {} shards: {}",
+                tenant_id,
+                shard_count,
+                response
+                    .new_shards
+                    .iter()
+                    .map(|s| format!("{:?}", s))
+                    .collect::<Vec<_>>()
+                    .join(",")
+            );
+        }
+        Command::TenantShardMigrate {
+            tenant_shard_id,
+            node,
+        } => {
+            let req = TenantShardMigrateRequest {
+                tenant_shard_id,
+                node_id: node,
+            };
+
+            storcon_client
+                .dispatch::<TenantShardMigrateRequest, TenantShardMigrateResponse>(
+                    Method::PUT,
+                    format!("control/v1/tenant/{tenant_shard_id}/migrate"),
+                    Some(req),
+                )
+                .await?;
+        }
+        Command::TenantConfig { tenant_id, config } => {
+            let tenant_conf = serde_json::from_str(&config)?;
+
+            vps_client
+                .tenant_config(&TenantConfigRequest {
+                    tenant_id,
+                    config: tenant_conf,
+                })
+                .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>(
+                    Method::GET,
+                    format!("control/v1/tenant/{tenant_id}"),
+                    None,
+                )
+                .await?;
+            let shards = describe_response.shards;
+            let mut table = comfy_table::Table::new();
+            table.set_header(["Shard", "Attached", "Secondary", "Last error", "status"]);
+            for shard in shards {
+                let secondary = shard
+                    .node_secondary
+                    .iter()
+                    .map(|n| format!("{}", n))
+                    .collect::<Vec<_>>()
+                    .join(",");
+
+                let mut status_parts = Vec::new();
+                if shard.is_reconciling {
+                    status_parts.push("reconciling");
+                }
+
+                if shard.is_pending_compute_notification {
+                    status_parts.push("pending_compute");
+                }
+
+                if shard.is_splitting {
+                    status_parts.push("splitting");
+                }
+                let status = status_parts.join(",");
+
+                table.add_row([
+                    format!("{}", shard.tenant_shard_id),
+                    shard
+                        .node_attached
+                        .map(|n| format!("{}", n))
+                        .unwrap_or(String::new()),
+                    secondary,
+                    shard.last_error,
+                    status,
+                ]);
+            }
+            println!("{table}");
+        }
+    }
+
+    Ok(())
+}
@@ -2,8 +2,8 @@
 # see https://diesel.rs/guides/configuring-diesel-cli

 [print_schema]
-file = "control_plane/attachment_service/src/schema.rs"
+file = "storage_controller/src/schema.rs"
 custom_type_derives = ["diesel::query_builder::QueryId"]

 [migrations_directory]
-dir = "control_plane/attachment_service/migrations"
+dir = "storage_controller/migrations"
@@ -7,6 +7,11 @@ Below you will find a brief overview of each subdir in the source tree in alphab
 Neon storage broker, providing messaging between safekeepers and pageservers.
 [storage_broker.md](./storage_broker.md)

+`storage_controller`:
+
+Neon storage controller, manages a cluster of pageservers and exposes an API that enables
+managing a many-sharded tenant as a single entity.
+
 `/control_plane`:

 Local control plane.
@@ -40,7 +40,7 @@ macro_rules! register_hll {
    }};

    ($N:literal, $NAME:expr, $HELP:expr $(,)?) => {{
-        $crate::register_hll!($N, $crate::opts!($NAME, $HELP), $LABELS_NAMES)
+        $crate::register_hll!($N, $crate::opts!($NAME, $HELP))
    }};
 }

@@ -2,11 +2,14 @@ use std::str::FromStr;

 /// Request/response types for the storage controller
 /// API (`/control/v1` prefix).  Implemented by the server
-/// in [`attachment_service::http`]
+/// in [`storage_controller::http`]
 use serde::{Deserialize, Serialize};
-use utils::id::NodeId;
+use utils::id::{NodeId, TenantId};

-use crate::{models::ShardParameters, shard::TenantShardId};
+use crate::{
+    models::{ShardParameters, TenantConfig},
+    shard::{ShardStripeSize, TenantShardId},
+};

 #[derive(Serialize, Deserialize)]
 pub struct TenantCreateResponseShard {
@@ -39,6 +42,12 @@ pub struct NodeConfigureRequest {
    pub scheduling: Option<NodeSchedulingPolicy>,
 }

+#[derive(Serialize, Deserialize)]
+pub struct TenantPolicyRequest {
+    pub placement: Option<PlacementPolicy>,
+    pub scheduling: Option<ShardSchedulingPolicy>,
+}
+
 #[derive(Serialize, Deserialize, Debug)]
 pub struct TenantLocateResponseShard {
    pub shard_id: TenantShardId,
@@ -57,6 +66,48 @@ pub struct TenantLocateResponse {
    pub shard_params: ShardParameters,
 }

+#[derive(Serialize, Deserialize)]
+pub struct TenantDescribeResponse {
+    pub tenant_id: TenantId,
+    pub shards: Vec<TenantDescribeResponseShard>,
+    pub stripe_size: ShardStripeSize,
+    pub policy: PlacementPolicy,
+    pub config: TenantConfig,
+}
+
+#[derive(Serialize, Deserialize)]
+pub struct NodeDescribeResponse {
+    pub id: NodeId,
+
+    pub availability: NodeAvailabilityWrapper,
+    pub scheduling: NodeSchedulingPolicy,
+
+    pub listen_http_addr: String,
+    pub listen_http_port: u16,
+
+    pub listen_pg_addr: String,
+    pub listen_pg_port: u16,
+}
+
+#[derive(Serialize, Deserialize)]
+pub struct TenantDescribeResponseShard {
+    pub tenant_shard_id: TenantShardId,
+
+    pub node_attached: Option<NodeId>,
+    pub node_secondary: Vec<NodeId>,
+
+    pub last_error: String,
+
+    /// A task is currently running to reconcile this tenant's intent state with the state on pageservers
+    pub is_reconciling: bool,
+    /// This shard failed in sending a compute notification to the cloud control plane, and a retry is pending.
+    pub is_pending_compute_notification: bool,
+    /// A shard split is currently underway
+    pub is_splitting: bool,
+
+    pub scheduling_policy: ShardSchedulingPolicy,
+}
+
 /// Explicitly migrating a particular shard is a low level operation
 /// TODO: higher level "Reschedule tenant" operation where the request
 /// specifies some constraints, e.g. asking it to get off particular node(s)
@@ -69,7 +120,7 @@ pub struct TenantShardMigrateRequest {
 /// Utilisation score indicating how good a candidate a pageserver
 /// is for scheduling the next tenant. See [`crate::models::PageserverUtilization`].
 /// Lower values are better.
-#[derive(Serialize, Deserialize, Clone, Copy, Eq, PartialEq, PartialOrd, Ord)]
+#[derive(Serialize, Deserialize, Clone, Copy, Eq, PartialEq, PartialOrd, Ord, Debug)]
 pub struct UtilizationScore(pub u64);

 impl UtilizationScore {
@@ -78,7 +129,7 @@ impl UtilizationScore {
    }
 }

-#[derive(Serialize, Clone, Copy)]
+#[derive(Serialize, Deserialize, Clone, Copy, Debug)]
 #[serde(into = "NodeAvailabilityWrapper")]
 pub enum NodeAvailability {
    // Normal, happy state
@@ -101,7 +152,7 @@ impl Eq for NodeAvailability {}
 // This wrapper provides serde functionality and it should only be used to
 // communicate with external callers which don't know or care about the
 // utilisation score of the pageserver it is targeting.
-#[derive(Serialize, Deserialize, Clone)]
+#[derive(Serialize, Deserialize, Clone, Copy, Debug)]
 pub enum NodeAvailabilityWrapper {
    Active,
    Offline,
@@ -127,22 +178,33 @@ impl From<NodeAvailability> for NodeAvailabilityWrapper {
    }
 }

-impl FromStr for NodeAvailability {
-    type Err = anyhow::Error;
+#[derive(Serialize, Deserialize, Clone, Copy, Eq, PartialEq, Debug)]
+pub enum ShardSchedulingPolicy {
+    // Normal mode: the tenant's scheduled locations may be updated at will, including
+    // for non-essential optimization.
+    Active,

-    fn from_str(s: &str) -> Result<Self, Self::Err> {
-        match s {
-            // This is used when parsing node configuration requests from neon-local.
-            // Assume the worst possible utilisation score
-            // and let it get updated via the heartbeats.
-            "active" => Ok(Self::Active(UtilizationScore::worst())),
-            "offline" => Ok(Self::Offline),
-            _ => Err(anyhow::anyhow!("Unknown availability state '{s}'")),
-        }
+    // Disable optimizations, but permit scheduling when necessary to fulfil the PlacementPolicy.
+    // For example, this still permits a node's attachment location to change to a secondary in
+    // response to a node failure, or to assign a new secondary if a node was removed.
+    Essential,
+
+    // No scheduling: leave the shard running wherever it currently is.  Even if the shard is
+    // unavailable, it will not be rescheduled to another node.
+    Pause,
+
+    // No reconciling: we will make no location_conf API calls to pageservers at all.  If the
+    // shard is unavailable, it stays that way.  If a node fails, this shard doesn't get failed over.
+    Stop,
+}
+
+impl Default for ShardSchedulingPolicy {
+    fn default() -> Self {
+        Self::Active
    }
 }

-#[derive(Serialize, Deserialize, Clone, Copy, Eq, PartialEq)]
+#[derive(Serialize, Deserialize, Clone, Copy, Eq, PartialEq, Debug)]
 pub enum NodeSchedulingPolicy {
    Active,
    Filling,
@@ -181,11 +243,8 @@ impl From<NodeSchedulingPolicy> for String {
 /// to create secondary locations.
 #[derive(Clone, Serialize, Deserialize, Debug, PartialEq, Eq)]
 pub enum PlacementPolicy {
-    /// Cheapest way to attach a tenant: just one pageserver, no secondary
-    Single,
-    /// Production-ready way to attach a tenant: one attached pageserver and
-    /// some number of secondaries.
-    Double(usize),
+    /// Normal live state: one attached pageserver and zero or more secondaries.
+    Attached(usize),
    /// Create one secondary mode locations. This is useful when onboarding
    /// a tenant, or for an idle tenant that we might want to bring online quickly.
    Secondary,
@@ -207,14 +266,14 @@ mod test {
    /// Check stability of PlacementPolicy's serialization
    #[test]
    fn placement_policy_encoding() -> anyhow::Result<()> {
-        let v = PlacementPolicy::Double(1);
+        let v = PlacementPolicy::Attached(1);
        let encoded = serde_json::to_string(&v)?;
-        assert_eq!(encoded, "{\"Double\":1}");
+        assert_eq!(encoded, "{\"Attached\":1}");
        assert_eq!(serde_json::from_str::<PlacementPolicy>(&encoded)?, v);

-        let v = PlacementPolicy::Single;
+        let v = PlacementPolicy::Detached;
        let encoded = serde_json::to_string(&v)?;
-        assert_eq!(encoded, "\"Single\"");
+        assert_eq!(encoded, "\"Detached\"");
        assert_eq!(serde_json::from_str::<PlacementPolicy>(&encoded)?, v);
        Ok(())
    }
@@ -301,6 +301,7 @@ pub struct TenantConfig {
    pub heatmap_period: Option<String>,
    pub lazy_slru_download: Option<bool>,
    pub timeline_get_throttle: Option<ThrottleConfig>,
+    pub image_layer_creation_check_threshold: Option<u8>,
 }

 #[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
@@ -6,7 +6,9 @@
 use serde::{Deserialize, Serialize};
 use utils::id::NodeId;

-use crate::{controller_api::NodeRegisterRequest, shard::TenantShardId};
+use crate::{
+    controller_api::NodeRegisterRequest, models::LocationConfigMode, shard::TenantShardId,
+};

 /// Upcall message sent by the pageserver to the configured `control_plane_api` on
 /// startup.
@@ -20,12 +22,20 @@ pub struct ReAttachRequest {
    pub register: Option<NodeRegisterRequest>,
 }

-#[derive(Serialize, Deserialize)]
-pub struct ReAttachResponseTenant {
-    pub id: TenantShardId,
-    pub gen: u32,
+fn default_mode() -> LocationConfigMode {
+    LocationConfigMode::AttachedSingle
 }

+#[derive(Serialize, Deserialize, Debug)]
+pub struct ReAttachResponseTenant {
+    pub id: TenantShardId,
+    /// Mandatory if LocationConfigMode is None or set to an Attached* mode
+    pub gen: Option<u32>,
+
+    /// Default value only for backward compat: this field should be set
+    #[serde(default = "default_mode")]
+    pub mode: LocationConfigMode,
+}
 #[derive(Serialize, Deserialize)]
 pub struct ReAttachResponse {
    pub tenants: Vec<ReAttachResponseTenant>,
@@ -1,5 +1,6 @@
 use anyhow::*;
 use clap::{value_parser, Arg, ArgMatches, Command};
+use postgres::Client;
 use std::{path::PathBuf, str::FromStr};
 use wal_craft::*;

@@ -8,8 +9,8 @@ fn main() -> Result<()> {
        .init();
    let arg_matches = cli().get_matches();

-    let wal_craft = |arg_matches: &ArgMatches, client| {
-        let (intermediate_lsns, end_of_wal_lsn) = match arg_matches
+    let wal_craft = |arg_matches: &ArgMatches, client: &mut Client| {
+        let intermediate_lsns = match arg_matches
            .get_one::<String>("type")
            .map(|s| s.as_str())
            .context("'type' is required")?
@@ -25,6 +26,7 @@ fn main() -> Result<()> {
            LastWalRecordCrossingSegment::NAME => LastWalRecordCrossingSegment::craft(client)?,
            a => panic!("Unknown --type argument: {a}"),
        };
+        let end_of_wal_lsn = client.pg_current_wal_insert_lsn()?;
        for lsn in intermediate_lsns {
            println!("intermediate_lsn = {lsn}");
        }
@@ -5,7 +5,6 @@ use postgres::types::PgLsn;
 use postgres::Client;
 use postgres_ffi::{WAL_SEGMENT_SIZE, XLOG_BLCKSZ};
 use postgres_ffi::{XLOG_SIZE_OF_XLOG_RECORD, XLOG_SIZE_OF_XLOG_SHORT_PHD};
-use std::cmp::Ordering;
 use std::path::{Path, PathBuf};
 use std::process::Command;
 use std::time::{Duration, Instant};
@@ -232,59 +231,52 @@ pub fn ensure_server_config(client: &mut impl postgres::GenericClient) -> anyhow
 pub trait Crafter {
    const NAME: &'static str;

-    /// Generates WAL using the client `client`. Returns a pair of:
-    /// * A vector of some valid "interesting" intermediate LSNs which one may start reading from.
-    ///   May include or exclude Lsn(0) and the end-of-wal.
-    /// * The expected end-of-wal LSN.
-    fn craft(client: &mut impl postgres::GenericClient) -> anyhow::Result<(Vec<PgLsn>, PgLsn)>;
+    /// Generates WAL using the client `client`. Returns a vector of some valid
+    /// "interesting" intermediate LSNs which one may start reading from.
+    /// test_end_of_wal uses this to check various starting points.
+    ///
+    /// Note that postgres is generally keen about writing some WAL. While we
+    /// try to disable it (autovacuum, big wal_writer_delay, etc) it is always
+    /// possible, e.g. xl_running_xacts are dumped each 15s. So checks about
+    /// stable WAL end would be flaky unless postgres is shut down. For this
+    /// reason returning potential end of WAL here is pointless. Most of the
+    /// time this doesn't happen though, so it is reasonable to create needed
+    /// WAL structure and immediately kill postgres like test_end_of_wal does.
+    fn craft(client: &mut impl postgres::GenericClient) -> anyhow::Result<Vec<PgLsn>>;
 }

+/// Wraps some WAL craft function, providing current LSN to it before the
+/// insertion and flushing WAL afterwards. Also pushes initial LSN to the
+/// result.
 fn craft_internal<C: postgres::GenericClient>(
    client: &mut C,
-    f: impl Fn(&mut C, PgLsn) -> anyhow::Result<(Vec<PgLsn>, Option<PgLsn>)>,
-) -> anyhow::Result<(Vec<PgLsn>, PgLsn)> {
+    f: impl Fn(&mut C, PgLsn) -> anyhow::Result<Vec<PgLsn>>,
+) -> anyhow::Result<Vec<PgLsn>> {
    ensure_server_config(client)?;

    let initial_lsn = client.pg_current_wal_insert_lsn()?;
    info!("LSN initial = {}", initial_lsn);

-    let (mut intermediate_lsns, last_lsn) = f(client, initial_lsn)?;
-    let last_lsn = match last_lsn {
-        None => client.pg_current_wal_insert_lsn()?,
-        Some(last_lsn) => {
-            let insert_lsn = client.pg_current_wal_insert_lsn()?;
-            match last_lsn.cmp(&insert_lsn) {
-                Ordering::Less => bail!(
-                    "Some records were inserted after the crafted WAL: {} vs {}",
-                    last_lsn,
-                    insert_lsn
-                ),
-                Ordering::Equal => last_lsn,
-                Ordering::Greater => bail!("Reported LSN is greater than insert_lsn"),
-            }
-        }
-    };
+    let mut intermediate_lsns = f(client, initial_lsn)?;
    if !intermediate_lsns.starts_with(&[initial_lsn]) {
        intermediate_lsns.insert(0, initial_lsn);
    }

    // Some records may be not flushed, e.g. non-transactional logical messages.
+    //
+    // Note: this is broken if pg_current_wal_insert_lsn is at page boundary
+    // because pg_current_wal_insert_lsn skips page headers.
    client.execute("select neon_xlogflush(pg_current_wal_insert_lsn())", &[])?;
-    match last_lsn.cmp(&client.pg_current_wal_flush_lsn()?) {
-        Ordering::Less => bail!("Some records were flushed after the crafted WAL"),
-        Ordering::Equal => {}
-        Ordering::Greater => bail!("Reported LSN is greater than flush_lsn"),
-    }
-    Ok((intermediate_lsns, last_lsn))
+    Ok(intermediate_lsns)
 }

 pub struct Simple;
 impl Crafter for Simple {
    const NAME: &'static str = "simple";
-    fn craft(client: &mut impl postgres::GenericClient) -> anyhow::Result<(Vec<PgLsn>, PgLsn)> {
+    fn craft(client: &mut impl postgres::GenericClient) -> anyhow::Result<Vec<PgLsn>> {
        craft_internal(client, |client, _| {
            client.execute("CREATE table t(x int)", &[])?;
-            Ok((Vec::new(), None))
+            Ok(Vec::new())
        })
    }
 }
@@ -292,29 +284,36 @@ impl Crafter for Simple {
 pub struct LastWalRecordXlogSwitch;
 impl Crafter for LastWalRecordXlogSwitch {
    const NAME: &'static str = "last_wal_record_xlog_switch";
-    fn craft(client: &mut impl postgres::GenericClient) -> anyhow::Result<(Vec<PgLsn>, PgLsn)> {
-        // Do not use generate_internal because here we end up with flush_lsn exactly on
+    fn craft(client: &mut impl postgres::GenericClient) -> anyhow::Result<Vec<PgLsn>> {
+        // Do not use craft_internal because here we end up with flush_lsn exactly on
        // the segment boundary and insert_lsn after the initial page header, which is unusual.
        ensure_server_config(client)?;

        client.execute("CREATE table t(x int)", &[])?;
        let before_xlog_switch = client.pg_current_wal_insert_lsn()?;
-        let after_xlog_switch: PgLsn = client.query_one("SELECT pg_switch_wal()", &[])?.get(0);
-        let next_segment = PgLsn::from(0x0200_0000);
+        // pg_switch_wal returns end of last record of the switched segment,
+        // i.e. end of SWITCH itself.
+        let xlog_switch_record_end: PgLsn = client.query_one("SELECT pg_switch_wal()", &[])?.get(0);
+        let before_xlog_switch_u64 = u64::from(before_xlog_switch);
+        let next_segment = PgLsn::from(
+            before_xlog_switch_u64 - (before_xlog_switch_u64 % WAL_SEGMENT_SIZE as u64)
+                + WAL_SEGMENT_SIZE as u64,
+        );
        ensure!(
-            after_xlog_switch <= next_segment,
-            "XLOG_SWITCH message ended after the expected segment boundary: {} > {}",
-            after_xlog_switch,
+            xlog_switch_record_end <= next_segment,
+            "XLOG_SWITCH record ended after the expected segment boundary: {} > {}",
+            xlog_switch_record_end,
            next_segment
        );
-        Ok((vec![before_xlog_switch, after_xlog_switch], next_segment))
+        Ok(vec![before_xlog_switch, xlog_switch_record_end])
    }
 }

 pub struct LastWalRecordXlogSwitchEndsOnPageBoundary;
+/// Craft xlog SWITCH record ending at page boundary.
 impl Crafter for LastWalRecordXlogSwitchEndsOnPageBoundary {
    const NAME: &'static str = "last_wal_record_xlog_switch_ends_on_page_boundary";
-    fn craft(client: &mut impl postgres::GenericClient) -> anyhow::Result<(Vec<PgLsn>, PgLsn)> {
+    fn craft(client: &mut impl postgres::GenericClient) -> anyhow::Result<Vec<PgLsn>> {
        // Do not use generate_internal because here we end up with flush_lsn exactly on
        // the segment boundary and insert_lsn after the initial page header, which is unusual.
        ensure_server_config(client)?;
@@ -361,28 +360,29 @@ impl Crafter for LastWalRecordXlogSwitchEndsOnPageBoundary {

        // Emit the XLOG_SWITCH
        let before_xlog_switch = client.pg_current_wal_insert_lsn()?;
-        let after_xlog_switch: PgLsn = client.query_one("SELECT pg_switch_wal()", &[])?.get(0);
+        let xlog_switch_record_end: PgLsn = client.query_one("SELECT pg_switch_wal()", &[])?.get(0);
        let next_segment = PgLsn::from(0x0200_0000);
        ensure!(
-            after_xlog_switch < next_segment,
-            "XLOG_SWITCH message ended on or after the expected segment boundary: {} > {}",
-            after_xlog_switch,
+            xlog_switch_record_end < next_segment,
+            "XLOG_SWITCH record ended on or after the expected segment boundary: {} > {}",
+            xlog_switch_record_end,
            next_segment
        );
        ensure!(
-            u64::from(after_xlog_switch) as usize % XLOG_BLCKSZ == XLOG_SIZE_OF_XLOG_SHORT_PHD,
+            u64::from(xlog_switch_record_end) as usize % XLOG_BLCKSZ == XLOG_SIZE_OF_XLOG_SHORT_PHD,
            "XLOG_SWITCH message ended not on page boundary: {}, offset = {}",
-            after_xlog_switch,
-            u64::from(after_xlog_switch) as usize % XLOG_BLCKSZ
+            xlog_switch_record_end,
+            u64::from(xlog_switch_record_end) as usize % XLOG_BLCKSZ
        );
-        Ok((vec![before_xlog_switch, after_xlog_switch], next_segment))
+        Ok(vec![before_xlog_switch, xlog_switch_record_end])
    }
 }

-fn craft_single_logical_message(
+/// Write ~16MB logical message; it should cross WAL segment.
+fn craft_seg_size_logical_message(
    client: &mut impl postgres::GenericClient,
    transactional: bool,
-) -> anyhow::Result<(Vec<PgLsn>, PgLsn)> {
+) -> anyhow::Result<Vec<PgLsn>> {
    craft_internal(client, |client, initial_lsn| {
        ensure!(
            initial_lsn < PgLsn::from(0x0200_0000 - 1024 * 1024),
@@ -405,34 +405,24 @@ fn craft_single_logical_message(
            "Logical message crossed two segments"
        );

-        if transactional {
-            // Transactional logical messages are part of a transaction, so the one above is
-            // followed by a small COMMIT record.
-
-            let after_message_lsn = client.pg_current_wal_insert_lsn()?;
-            ensure!(
-                message_lsn < after_message_lsn,
-                "No record found after the emitted message"
-            );
-            Ok((vec![message_lsn], Some(after_message_lsn)))
-        } else {
-            Ok((Vec::new(), Some(message_lsn)))
-        }
+        Ok(vec![message_lsn])
    })
 }

 pub struct WalRecordCrossingSegmentFollowedBySmallOne;
 impl Crafter for WalRecordCrossingSegmentFollowedBySmallOne {
    const NAME: &'static str = "wal_record_crossing_segment_followed_by_small_one";
-    fn craft(client: &mut impl postgres::GenericClient) -> anyhow::Result<(Vec<PgLsn>, PgLsn)> {
-        craft_single_logical_message(client, true)
+    fn craft(client: &mut impl postgres::GenericClient) -> anyhow::Result<Vec<PgLsn>> {
+        // Transactional message crossing WAL segment will be followed by small
+        // commit record.
+        craft_seg_size_logical_message(client, true)
    }
 }

 pub struct LastWalRecordCrossingSegment;
 impl Crafter for LastWalRecordCrossingSegment {
    const NAME: &'static str = "last_wal_record_crossing_segment";
-    fn craft(client: &mut impl postgres::GenericClient) -> anyhow::Result<(Vec<PgLsn>, PgLsn)> {
-        craft_single_logical_message(client, false)
+    fn craft(client: &mut impl postgres::GenericClient) -> anyhow::Result<Vec<PgLsn>> {
+        craft_seg_size_logical_message(client, false)
    }
 }
@@ -11,13 +11,15 @@ use utils::const_assert;
 use utils::lsn::Lsn;

 fn init_logging() {
-    let _ = env_logger::Builder::from_env(env_logger::Env::default().default_filter_or(
-        format!("crate=info,postgres_ffi::{PG_MAJORVERSION}::xlog_utils=trace"),
-    ))
+    let _ = env_logger::Builder::from_env(env_logger::Env::default().default_filter_or(format!(
+        "crate=info,postgres_ffi::{PG_MAJORVERSION}::xlog_utils=trace"
+    )))
    .is_test(true)
    .try_init();
 }

+/// Test that find_end_of_wal returns the same results as pg_dump on various
+/// WALs created by Crafter.
 fn test_end_of_wal<C: crate::Crafter>(test_name: &str) {
    use crate::*;

@@ -38,13 +40,13 @@ fn test_end_of_wal<C: crate::Crafter>(test_name: &str) {
    }
    cfg.initdb().unwrap();
    let srv = cfg.start_server().unwrap();
-    let (intermediate_lsns, expected_end_of_wal_partial) =
-        C::craft(&mut srv.connect_with_timeout().unwrap()).unwrap();
+    let intermediate_lsns = C::craft(&mut srv.connect_with_timeout().unwrap()).unwrap();
    let intermediate_lsns: Vec<Lsn> = intermediate_lsns
        .iter()
        .map(|&lsn| u64::from(lsn).into())
        .collect();
-    let expected_end_of_wal: Lsn = u64::from(expected_end_of_wal_partial).into();
+    // Kill postgres. Note that it might have inserted to WAL something after
+    // 'craft' did its job.
    srv.kill();

    // Check find_end_of_wal on the initial WAL
@@ -56,7 +58,7 @@ fn test_end_of_wal<C: crate::Crafter>(test_name: &str) {
        .filter(|fname| IsXLogFileName(fname))
        .max()
        .unwrap();
-    check_pg_waldump_end_of_wal(&cfg, &last_segment, expected_end_of_wal);
+    let expected_end_of_wal = find_pg_waldump_end_of_wal(&cfg, &last_segment);
    for start_lsn in intermediate_lsns
        .iter()
        .chain(std::iter::once(&expected_end_of_wal))
@@ -91,11 +93,7 @@ fn test_end_of_wal<C: crate::Crafter>(test_name: &str) {
    }
 }

-fn check_pg_waldump_end_of_wal(
-    cfg: &crate::Conf,
-    last_segment: &str,
-    expected_end_of_wal: Lsn,
-) {
+fn find_pg_waldump_end_of_wal(cfg: &crate::Conf, last_segment: &str) -> Lsn {
    // Get the actual end of WAL by pg_waldump
    let waldump_output = cfg
        .pg_waldump("000000010000000000000001", last_segment)
@@ -113,11 +111,8 @@ fn check_pg_waldump_end_of_wal(
        }
    };
    let waldump_wal_end = Lsn::from_str(caps.get(1).unwrap().as_str()).unwrap();
-    info!(
-        "waldump erred on {}, expected wal end at {}",
-        waldump_wal_end, expected_end_of_wal
-    );
-    assert_eq!(waldump_wal_end, expected_end_of_wal);
+    info!("waldump erred on {}", waldump_wal_end);
+    waldump_wal_end
 }

 fn check_end_of_wal(
@@ -210,9 +205,9 @@ pub fn test_update_next_xid() {
 #[test]
 pub fn test_encode_logical_message() {
    let expected = [
-        64, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 21, 0, 0, 170, 34, 166, 227, 255,
-        38, 0, 0, 0, 0, 0, 0, 0, 0, 7, 0, 0, 0, 0, 0, 0, 0, 7, 0, 0, 0, 0, 0, 0, 0, 112, 114,
-        101, 102, 105, 120, 0, 109, 101, 115, 115, 97, 103, 101,
+        64, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 21, 0, 0, 170, 34, 166, 227, 255, 38,
+        0, 0, 0, 0, 0, 0, 0, 0, 7, 0, 0, 0, 0, 0, 0, 0, 7, 0, 0, 0, 0, 0, 0, 0, 112, 114, 101, 102,
+        105, 120, 0, 109, 101, 115, 115, 97, 103, 101,
    ];
    let actual = encode_logical_message("prefix", "message");
    assert_eq!(expected, actual[..]);
@@ -565,6 +565,16 @@ impl GenericRemoteStorage {
 #[derive(Debug, Clone, PartialEq, Eq)]
 pub struct StorageMetadata(HashMap<String, String>);

+impl<const N: usize> From<[(&str, &str); N]> for StorageMetadata {
+    fn from(arr: [(&str, &str); N]) -> Self {
+        let map: HashMap<String, String> = arr
+            .iter()
+            .map(|(k, v)| (k.to_string(), v.to_string()))
+            .collect();
+        Self(map)
+    }
+}
+
 /// External backup storage configuration, enough for creating a client for that storage.
 #[derive(Debug, Clone, PartialEq, Eq)]
 pub struct RemoteStorageConfig {
@@ -198,6 +198,7 @@ impl LocalFs {
            fs::OpenOptions::new()
                .write(true)
                .create(true)
+                .truncate(true)
                .open(&temp_file_path)
                .await
                .with_context(|| {
@@ -57,7 +57,6 @@ enum MaybeEnabledStorage {
    Disabled,
 }

-#[async_trait::async_trait]
 impl AsyncTestContext for MaybeEnabledStorage {
    async fn setup() -> Self {
        ensure_logging_ready();
@@ -86,7 +85,6 @@ struct AzureWithTestBlobs {
    remote_blobs: HashSet<RemotePath>,
 }

-#[async_trait::async_trait]
 impl AsyncTestContext for MaybeEnabledStorageWithTestBlobs {
    async fn setup() -> Self {
        ensure_logging_ready();
@@ -148,7 +146,6 @@ struct AzureWithSimpleTestBlobs {
    remote_blobs: HashSet<RemotePath>,
 }

-#[async_trait::async_trait]
 impl AsyncTestContext for MaybeEnabledStorageWithSimpleTestBlobs {
    async fn setup() -> Self {
        ensure_logging_ready();
@@ -219,7 +219,6 @@ enum MaybeEnabledStorage {
    Disabled,
 }

-#[async_trait::async_trait]
 impl AsyncTestContext for MaybeEnabledStorage {
    async fn setup() -> Self {
        ensure_logging_ready();
@@ -248,7 +247,6 @@ struct S3WithTestBlobs {
    remote_blobs: HashSet<RemotePath>,
 }

-#[async_trait::async_trait]
 impl AsyncTestContext for MaybeEnabledStorageWithTestBlobs {
    async fn setup() -> Self {
        ensure_logging_ready();
@@ -310,7 +308,6 @@ struct S3WithSimpleTestBlobs {
    remote_blobs: HashSet<RemotePath>,
 }

-#[async_trait::async_trait]
 impl AsyncTestContext for MaybeEnabledStorageWithSimpleTestBlobs {
    async fn setup() -> Self {
        ensure_logging_ready();
@@ -247,7 +247,7 @@ fn scenario_4() {
    //
    // This is in total 5000 + 1000 + 5000 + 1000 = 12000
    //
-    // (If we used the the method from the previous scenario, and
+    // (If we used the method from the previous scenario, and
    // kept only snapshot at the branch point, we'd need to keep
    // all the WAL between 10000-18000 on the main branch, so
    // the total size would be 5000 + 1000 + 8000 = 14000. The
@@ -13,6 +13,7 @@ testing = ["fail/failpoints"]
 [dependencies]
 arc-swap.workspace = true
 sentry.workspace = true
+async-compression.workspace = true
 async-trait.workspace = true
 anyhow.workspace = true
 bincode.workspace = true
@@ -36,6 +37,7 @@ serde_json.workspace = true
 signal-hook.workspace = true
 thiserror.workspace = true
 tokio.workspace = true
+tokio-tar.workspace = true
 tokio-util.workspace = true
 tracing.workspace = true
 tracing-error.workspace = true
@@ -46,6 +48,7 @@ strum.workspace = true
 strum_macros.workspace = true
 url.workspace = true
 uuid.workspace = true
+walkdir.workspace = true

 pq_proto.workspace = true
 postgres_connection.workspace = true
@@ -245,7 +245,7 @@ impl std::io::Write for ChannelWriter {
    }
 }

-async fn prometheus_metrics_handler(_req: Request<Body>) -> Result<Response<Body>, ApiError> {
+pub async fn prometheus_metrics_handler(_req: Request<Body>) -> Result<Response<Body>, ApiError> {
    SERVE_METRICS_COUNT.inc();

    let started_at = std::time::Instant::now();
@@ -367,7 +367,6 @@ pub fn make_router() -> RouterBuilder<hyper::Body, ApiError> {
        .middleware(Middleware::post_with_info(
            add_request_id_header_to_response,
        ))
-        .get("/metrics", |r| request_span(r, prometheus_metrics_handler))
        .err_handler(route_error_handler)
 }

@@ -87,6 +87,8 @@ pub mod failpoint_support;

 pub mod yielding_loop;

+pub mod zstd;
+
 /// This is a shortcut to embed git sha into binaries and avoid copying the same build script to all packages
 ///
 /// we have several cases:
@@ -63,6 +63,7 @@ impl UnwrittenLockFile {
 pub fn create_exclusive(lock_file_path: &Utf8Path) -> anyhow::Result<UnwrittenLockFile> {
    let lock_file = fs::OpenOptions::new()
        .create(true) // O_CREAT
+        .truncate(true)
        .write(true)
        .open(lock_file_path)
        .context("open lock file")?;
@@ -182,6 +182,18 @@ where
        }
    }

+    /// Check if [`Self::wait_for`] or [`Self::wait_for_timeout`] would wait if called with `num`.
+    pub fn would_wait_for(&self, num: V) -> Result<(), V> {
+        let internal = self.internal.lock().unwrap();
+        let cnt = internal.current.cnt_value();
+        drop(internal);
+        if cnt >= num {
+            Ok(())
+        } else {
+            Err(cnt)
+        }
+    }
+
    /// Register and return a channel that will be notified when a number arrives,
    /// or None, if it has already arrived.
    fn queue_for_wait(&self, num: V) -> Result<Option<Receiver<()>>, SeqWaitError> {
@@ -245,7 +245,7 @@ impl<'a, T> Guard<'a, T> {
    ///
    /// The permit will be on a semaphore part of the new internal value, and any following
    /// [`OnceCell::get_or_init`] will wait on it to complete.
-    pub fn take_and_deinit(&mut self) -> (T, InitPermit) {
+    pub fn take_and_deinit(mut self) -> (T, InitPermit) {
        let mut swapped = Inner::default();
        let sem = swapped.init_semaphore.clone();
        // acquire and forget right away, moving the control over to InitPermit
@@ -543,7 +543,7 @@ mod tests {
        target.set(42, permit);

        let (_answer, permit) = {
-            let mut guard = target
+            let guard = target
                .get_or_init(|permit| async { Ok::<_, Infallible>((11, permit)) })
                .await
                .unwrap();
@@ -1,27 +1,60 @@
 use std::{alloc::Layout, cmp::Ordering, ops::RangeBounds};

+#[derive(Clone, Copy, Debug, PartialEq, Eq)]
+pub enum VecMapOrdering {
+    Greater,
+    GreaterOrEqual,
+}
+
 /// Ordered map datastructure implemented in a Vec.
 /// Append only - can only add keys that are larger than the
 /// current max key.
+/// Ordering can be adjusted using [`VecMapOrdering`]
+/// during `VecMap` construction.
 #[derive(Clone, Debug)]
-pub struct VecMap<K, V>(Vec<(K, V)>);
+pub struct VecMap<K, V> {
+    data: Vec<(K, V)>,
+    ordering: VecMapOrdering,
+}

 impl<K, V> Default for VecMap<K, V> {
    fn default() -> Self {
-        VecMap(Default::default())
+        VecMap {
+            data: Default::default(),
+            ordering: VecMapOrdering::Greater,
+        }
    }
 }

-#[derive(Debug)]
-pub struct InvalidKey;
+#[derive(thiserror::Error, Debug)]
+pub enum VecMapError {
+    #[error("Key violates ordering constraint")]
+    InvalidKey,
+    #[error("Mismatched ordering constraints")]
+    ExtendOrderingError,
+}

 impl<K: Ord, V> VecMap<K, V> {
+    pub fn new(ordering: VecMapOrdering) -> Self {
+        Self {
+            data: Vec::new(),
+            ordering,
+        }
+    }
+
+    pub fn with_capacity(capacity: usize, ordering: VecMapOrdering) -> Self {
+        Self {
+            data: Vec::with_capacity(capacity),
+            ordering,
+        }
+    }
+
    pub fn is_empty(&self) -> bool {
-        self.0.is_empty()
+        self.data.is_empty()
    }

    pub fn as_slice(&self) -> &[(K, V)] {
-        self.0.as_slice()
+        self.data.as_slice()
    }

    /// This function may panic if given a range where the lower bound is
@@ -29,7 +62,7 @@ impl<K: Ord, V> VecMap<K, V> {
    pub fn slice_range<R: RangeBounds<K>>(&self, range: R) -> &[(K, V)] {
        use std::ops::Bound::*;

-        let binary_search = |k: &K| self.0.binary_search_by_key(&k, extract_key);
+        let binary_search = |k: &K| self.data.binary_search_by_key(&k, extract_key);

        let start_idx = match range.start_bound() {
            Unbounded => 0,
@@ -41,7 +74,7 @@ impl<K: Ord, V> VecMap<K, V> {
        };

        let end_idx = match range.end_bound() {
-            Unbounded => self.0.len(),
+            Unbounded => self.data.len(),
            Included(k) => match binary_search(k) {
                Ok(idx) => idx + 1,
                Err(idx) => idx,
@@ -49,34 +82,30 @@ impl<K: Ord, V> VecMap<K, V> {
            Excluded(k) => binary_search(k).unwrap_or_else(std::convert::identity),
        };

-        &self.0[start_idx..end_idx]
+        &self.data[start_idx..end_idx]
    }

    /// Add a key value pair to the map.
-    /// If `key` is less than or equal to the current maximum key
-    /// the pair will not be added and InvalidKey error will be returned.
-    pub fn append(&mut self, key: K, value: V) -> Result<usize, InvalidKey> {
-        if let Some((last_key, _last_value)) = self.0.last() {
-            if &key <= last_key {
-                return Err(InvalidKey);
-            }
-        }
+    /// If `key` is not respective of the `self` ordering the
+    /// pair will not be added and `InvalidKey` error will be returned.
+    pub fn append(&mut self, key: K, value: V) -> Result<usize, VecMapError> {
+        self.validate_key_order(&key)?;

        let delta_size = self.instrument_vec_op(|vec| vec.push((key, value)));
        Ok(delta_size)
    }

    /// Update the maximum key value pair or add a new key value pair to the map.
-    /// If `key` is less than the current maximum key no updates or additions
-    /// will occur and InvalidKey error will be returned.
+    /// If `key` is not respective of the `self` ordering no updates or additions
+    /// will occur and `InvalidKey` error will be returned.
    pub fn append_or_update_last(
        &mut self,
        key: K,
        mut value: V,
-    ) -> Result<(Option<V>, usize), InvalidKey> {
-        if let Some((last_key, last_value)) = self.0.last_mut() {
+    ) -> Result<(Option<V>, usize), VecMapError> {
+        if let Some((last_key, last_value)) = self.data.last_mut() {
            match key.cmp(last_key) {
-                Ordering::Less => return Err(InvalidKey),
+                Ordering::Less => return Err(VecMapError::InvalidKey),
                Ordering::Equal => {
                    std::mem::swap(last_value, &mut value);
                    const DELTA_SIZE: usize = 0;
@@ -100,40 +129,67 @@ impl<K: Ord, V> VecMap<K, V> {
        V: Clone,
    {
        let split_idx = self
-            .0
+            .data
            .binary_search_by_key(&cutoff, extract_key)
            .unwrap_or_else(std::convert::identity);

        (
-            VecMap(self.0[..split_idx].to_vec()),
-            VecMap(self.0[split_idx..].to_vec()),
+            VecMap {
+                data: self.data[..split_idx].to_vec(),
+                ordering: self.ordering,
+            },
+            VecMap {
+                data: self.data[split_idx..].to_vec(),
+                ordering: self.ordering,
+            },
        )
    }

    /// Move items from `other` to the end of `self`, leaving `other` empty.
-    /// If any keys in `other` is less than or equal to any key in `self`,
-    /// `InvalidKey` error will be returned and no mutation will occur.
-    pub fn extend(&mut self, other: &mut Self) -> Result<usize, InvalidKey> {
-        let self_last_opt = self.0.last().map(extract_key);
-        let other_first_opt = other.0.last().map(extract_key);
+    /// If the `other` ordering is different from `self` ordering
+    /// `ExtendOrderingError` error will be returned.
+    /// If any keys in `other` is not respective of the ordering defined in
+    /// `self`, `InvalidKey` error will be returned and no mutation will occur.
+    pub fn extend(&mut self, other: &mut Self) -> Result<usize, VecMapError> {
+        if self.ordering != other.ordering {
+            return Err(VecMapError::ExtendOrderingError);
+        }

-        if let (Some(self_last), Some(other_first)) = (self_last_opt, other_first_opt) {
-            if self_last >= other_first {
-                return Err(InvalidKey);
+        let other_first_opt = other.data.last().map(extract_key);
+        if let Some(other_first) = other_first_opt {
+            self.validate_key_order(other_first)?;
+        }
+
+        let delta_size = self.instrument_vec_op(|vec| vec.append(&mut other.data));
+        Ok(delta_size)
+    }
+
+    /// Validate the current last key in `self` and key being
+    /// inserted against the order defined in `self`.
+    fn validate_key_order(&self, key: &K) -> Result<(), VecMapError> {
+        if let Some(last_key) = self.data.last().map(extract_key) {
+            match (&self.ordering, &key.cmp(last_key)) {
+                (VecMapOrdering::Greater, Ordering::Less | Ordering::Equal) => {
+                    return Err(VecMapError::InvalidKey);
+                }
+                (VecMapOrdering::Greater, Ordering::Greater) => {}
+                (VecMapOrdering::GreaterOrEqual, Ordering::Less) => {
+                    return Err(VecMapError::InvalidKey);
+                }
+                (VecMapOrdering::GreaterOrEqual, Ordering::Equal | Ordering::Greater) => {}
            }
        }

-        let delta_size = self.instrument_vec_op(|vec| vec.append(&mut other.0));
-        Ok(delta_size)
+        Ok(())
    }

    /// Instrument an operation on the underlying [`Vec`].
    /// Will panic if the operation decreases capacity.
    /// Returns the increase in memory usage caused by the op.
    fn instrument_vec_op(&mut self, op: impl FnOnce(&mut Vec<(K, V)>)) -> usize {
-        let old_cap = self.0.capacity();
-        op(&mut self.0);
-        let new_cap = self.0.capacity();
+        let old_cap = self.data.capacity();
+        op(&mut self.data);
+        let new_cap = self.data.capacity();

        match old_cap.cmp(&new_cap) {
            Ordering::Less => {
@@ -145,6 +201,36 @@ impl<K: Ord, V> VecMap<K, V> {
            Ordering::Greater => panic!("VecMap capacity shouldn't ever decrease"),
        }
    }
+
+    /// Similar to `from_iter` defined in `FromIter` trait except
+    /// that it accepts an [`VecMapOrdering`]
+    pub fn from_iter<I: IntoIterator<Item = (K, V)>>(iter: I, ordering: VecMapOrdering) -> Self {
+        let iter = iter.into_iter();
+        let initial_capacity = {
+            match iter.size_hint() {
+                (lower_bound, None) => lower_bound,
+                (_, Some(upper_bound)) => upper_bound,
+            }
+        };
+
+        let mut vec_map = VecMap::with_capacity(initial_capacity, ordering);
+        for (key, value) in iter {
+            vec_map
+                .append(key, value)
+                .expect("The passed collection needs to be sorted!");
+        }
+
+        vec_map
+    }
+}
+
+impl<K: Ord, V> IntoIterator for VecMap<K, V> {
+    type Item = (K, V);
+    type IntoIter = std::vec::IntoIter<(K, V)>;
+
+    fn into_iter(self) -> Self::IntoIter {
+        self.data.into_iter()
+    }
 }

 fn extract_key<K, V>(entry: &(K, V)) -> &K {
@@ -155,7 +241,7 @@ fn extract_key<K, V>(entry: &(K, V)) -> &K {
 mod tests {
    use std::{collections::BTreeMap, ops::Bound};

-    use super::VecMap;
+    use super::{VecMap, VecMapOrdering};

    #[test]
    fn unbounded_range() {
@@ -310,5 +396,59 @@ mod tests {
        left.extend(&mut one_map).unwrap_err();
        assert_eq!(left.as_slice(), &[(0, ()), (1, ())]);
        assert_eq!(one_map.as_slice(), &[(1, ())]);
+
+        let mut map_greater_or_equal = VecMap::new(VecMapOrdering::GreaterOrEqual);
+        map_greater_or_equal.append(2, ()).unwrap();
+        map_greater_or_equal.append(2, ()).unwrap();
+
+        left.extend(&mut map_greater_or_equal).unwrap_err();
+        assert_eq!(left.as_slice(), &[(0, ()), (1, ())]);
+        assert_eq!(map_greater_or_equal.as_slice(), &[(2, ()), (2, ())]);
+    }
+
+    #[test]
+    fn extend_with_ordering() {
+        let mut left = VecMap::new(VecMapOrdering::GreaterOrEqual);
+        left.append(0, ()).unwrap();
+        assert_eq!(left.as_slice(), &[(0, ())]);
+
+        let mut greater_right = VecMap::new(VecMapOrdering::Greater);
+        greater_right.append(0, ()).unwrap();
+        left.extend(&mut greater_right).unwrap_err();
+        assert_eq!(left.as_slice(), &[(0, ())]);
+
+        let mut greater_or_equal_right = VecMap::new(VecMapOrdering::GreaterOrEqual);
+        greater_or_equal_right.append(2, ()).unwrap();
+        greater_or_equal_right.append(2, ()).unwrap();
+        left.extend(&mut greater_or_equal_right).unwrap();
+        assert_eq!(left.as_slice(), &[(0, ()), (2, ()), (2, ())]);
+    }
+
+    #[test]
+    fn vec_map_from_sorted() {
+        let vec = vec![(1, ()), (2, ()), (3, ()), (6, ())];
+        let vec_map = VecMap::from_iter(vec, VecMapOrdering::Greater);
+        assert_eq!(vec_map.as_slice(), &[(1, ()), (2, ()), (3, ()), (6, ())]);
+
+        let vec = vec![(1, ()), (2, ()), (3, ()), (3, ()), (6, ()), (6, ())];
+        let vec_map = VecMap::from_iter(vec, VecMapOrdering::GreaterOrEqual);
+        assert_eq!(
+            vec_map.as_slice(),
+            &[(1, ()), (2, ()), (3, ()), (3, ()), (6, ()), (6, ())]
+        );
+    }
+
+    #[test]
+    #[should_panic]
+    fn vec_map_from_unsorted_greater() {
+        let vec = vec![(1, ()), (2, ()), (2, ()), (3, ()), (6, ())];
+        let _ = VecMap::from_iter(vec, VecMapOrdering::Greater);
+    }
+
+    #[test]
+    #[should_panic]
+    fn vec_map_from_unsorted_greater_or_equal() {
+        let vec = vec![(1, ()), (2, ()), (3, ()), (6, ()), (5, ())];
+        let _ = VecMap::from_iter(vec, VecMapOrdering::GreaterOrEqual);
    }
 }
@@ -0,0 +1,78 @@
+use std::io::SeekFrom;
+
+use anyhow::{Context, Result};
+use async_compression::{
+    tokio::{bufread::ZstdDecoder, write::ZstdEncoder},
+    zstd::CParameter,
+    Level,
+};
+use camino::Utf8Path;
+use nix::NixPath;
+use tokio::{
+    fs::{File, OpenOptions},
+    io::AsyncBufRead,
+    io::AsyncSeekExt,
+    io::AsyncWriteExt,
+};
+use tokio_tar::{Archive, Builder, HeaderMode};
+use walkdir::WalkDir;
+
+/// Creates a Zstandard tarball.
+pub async fn create_zst_tarball(path: &Utf8Path, tarball: &Utf8Path) -> Result<(File, u64)> {
+    let file = OpenOptions::new()
+        .create(true)
+        .truncate(true)
+        .read(true)
+        .write(true)
+        .open(&tarball)
+        .await
+        .with_context(|| format!("tempfile creation {tarball}"))?;
+
+    let mut paths = Vec::new();
+    for entry in WalkDir::new(path) {
+        let entry = entry?;
+        let metadata = entry.metadata().expect("error getting dir entry metadata");
+        // Also allow directories so that we also get empty directories
+        if !(metadata.is_file() || metadata.is_dir()) {
+            continue;
+        }
+        let path = entry.into_path();
+        paths.push(path);
+    }
+    // Do a sort to get a more consistent listing
+    paths.sort_unstable();
+    let zstd = ZstdEncoder::with_quality_and_params(
+        file,
+        Level::Default,
+        &[CParameter::enable_long_distance_matching(true)],
+    );
+    let mut builder = Builder::new(zstd);
+    // Use reproducible header mode
+    builder.mode(HeaderMode::Deterministic);
+    for p in paths {
+        let rel_path = p.strip_prefix(path)?;
+        if rel_path.is_empty() {
+            // The top directory should not be compressed,
+            // the tar crate doesn't like that
+            continue;
+        }
+        builder.append_path_with_name(&p, rel_path).await?;
+    }
+    let mut zstd = builder.into_inner().await?;
+    zstd.shutdown().await?;
+    let mut compressed = zstd.into_inner();
+    let compressed_len = compressed.metadata().await?.len();
+    compressed.seek(SeekFrom::Start(0)).await?;
+    Ok((compressed, compressed_len))
+}
+
+/// Creates a Zstandard tarball.
+pub async fn extract_zst_tarball(
+    path: &Utf8Path,
+    tarball: impl AsyncBufRead + Unpin,
+) -> Result<()> {
+    let decoder = Box::pin(ZstdDecoder::new(tarball));
+    let mut archive = Archive::new(decoder);
+    archive.unpack(path).await?;
+    Ok(())
+}
@@ -69,7 +69,7 @@ pub struct Config {
    /// should be removed once we have a better solution there.
    sys_buffer_bytes: u64,

-    /// Minimum fraction of total system memory reserved *before* the the cgroup threshold; in
+    /// Minimum fraction of total system memory reserved *before* the cgroup threshold; in
    /// other words, providing a ceiling for the highest value of the threshold by enforcing that
    /// there's at least `cgroup_min_overhead_fraction` of the total memory remaining beyond the
    /// threshold.
@@ -59,6 +59,7 @@ signal-hook.workspace = true
 smallvec = { workspace = true, features = ["write"] }
 svg_fmt.workspace = true
 sync_wrapper.workspace = true
+sysinfo.workspace = true
 tokio-tar.workspace = true
 thiserror.workspace = true
 tokio = { workspace = true, features = ["process", "sync", "fs", "rt", "io-util", "time"] }
@@ -1,160 +1,156 @@
-//! Simple benchmarking around walredo.
+//! Quantify a single walredo manager's throughput under N concurrent callers.
 //!
-//! Right now they hope to just set a baseline. Later we can try to expand into latency and
-//! throughput after figuring out the coordinated omission problems below.
+//! The benchmark implementation ([`bench_impl`]) is parametrized by
+//! - `redo_work` => [`Request::short_request`] or [`Request::medium_request`]
+//! - `n_redos` => number of times the benchmark shell execute the `redo_work`
+//! - `nclients` => number of clients (more on this shortly).
 //!
-//! There are two sets of inputs; `short` and `medium`. They were collected on postgres v14 by
-//! logging what happens when a sequential scan is requested on a small table, then picking out two
-//! suitable from logs.
+//! The benchmark impl sets up a multi-threaded tokio runtime with default parameters.
+//! It spawns `nclients` times [`client`] tokio tasks.
+//! Each task executes the `redo_work` `n_redos/nclients` times.
 //!
+//! We exercise the following combinations:
+//! - `redo_work = short / medium``
+//! - `nclients = [1, 2, 4, 8, 16, 32, 64, 128]`
 //!
-//! Reference data (git blame to see commit) on an i3en.3xlarge
-// ```text
-//! short/short/1           time:   [39.175 µs 39.348 µs 39.536 µs]
-//! short/short/2           time:   [51.227 µs 51.487 µs 51.755 µs]
-//! short/short/4           time:   [76.048 µs 76.362 µs 76.674 µs]
-//! short/short/8           time:   [128.94 µs 129.82 µs 130.74 µs]
-//! short/short/16          time:   [227.84 µs 229.00 µs 230.28 µs]
-//! short/short/32          time:   [455.97 µs 457.81 µs 459.90 µs]
-//! short/short/64          time:   [902.46 µs 904.84 µs 907.32 µs]
-//! short/short/128         time:   [1.7416 ms 1.7487 ms 1.7561 ms]
-//! ``
-
-use std::sync::Arc;
+//! We let `criterion` determine the `n_redos` using `iter_custom`.
+//! The idea is that for each `(redo_work, nclients)` combination,
+//! criterion will run the `bench_impl` multiple times with different `n_redos`.
+//! The `bench_impl` reports the aggregate wall clock time from the clients' perspective.
+//! Criterion will divide that by `n_redos` to compute the "time per iteration".
+//! In our case, "time per iteration" means "time per redo_work execution".
+//!
+//! NB: the way by which `iter_custom` determines the "number of iterations"
+//! is called sampling. Apparently the idea here is to detect outliers.
+//! We're not sure whether the current choice of sampling method makes sense.
+//! See https://bheisler.github.io/criterion.rs/book/user_guide/command_line_output.html#collecting-samples
+//!
+//! # Reference Numbers
+//!
+//! 2024-04-04 on i3en.3xlarge
+//!
+//! ```text
+//! short/1                 time:   [25.925 µs 26.060 µs 26.209 µs]
+//! short/2                 time:   [31.277 µs 31.483 µs 31.722 µs]
+//! short/4                 time:   [45.496 µs 45.831 µs 46.182 µs]
+//! short/8                 time:   [84.298 µs 84.920 µs 85.566 µs]
+//! short/16                time:   [185.04 µs 186.41 µs 187.88 µs]
+//! short/32                time:   [385.01 µs 386.77 µs 388.70 µs]
+//! short/64                time:   [770.24 µs 773.04 µs 776.04 µs]
+//! short/128               time:   [1.5017 ms 1.5064 ms 1.5113 ms]
+//! medium/1                time:   [106.65 µs 107.20 µs 107.85 µs]
+//! medium/2                time:   [153.28 µs 154.24 µs 155.56 µs]
+//! medium/4                time:   [325.67 µs 327.01 µs 328.71 µs]
+//! medium/8                time:   [646.82 µs 650.17 µs 653.91 µs]
+//! medium/16               time:   [1.2645 ms 1.2701 ms 1.2762 ms]
+//! medium/32               time:   [2.4409 ms 2.4550 ms 2.4692 ms]
+//! medium/64               time:   [4.6814 ms 4.7114 ms 4.7408 ms]
+//! medium/128              time:   [8.7790 ms 8.9037 ms 9.0282 ms]
+//! ```

 use bytes::{Buf, Bytes};
-use pageserver::{
-    config::PageServerConf, repository::Key, walrecord::NeonWalRecord, walredo::PostgresRedoManager,
+use criterion::{BenchmarkId, Criterion};
+use pageserver::{config::PageServerConf, walrecord::NeonWalRecord, walredo::PostgresRedoManager};
+use pageserver_api::{key::Key, shard::TenantShardId};
+use std::{
+    sync::Arc,
+    time::{Duration, Instant},
 };
-use pageserver_api::shard::TenantShardId;
-use tokio::task::JoinSet;
+use tokio::{sync::Barrier, task::JoinSet};
 use utils::{id::TenantId, lsn::Lsn};

-use criterion::{criterion_group, criterion_main, BenchmarkId, Criterion};
+fn bench(c: &mut Criterion) {
+    {
+        let nclients = [1, 2, 4, 8, 16, 32, 64, 128];
+        for nclients in nclients {
+            let mut group = c.benchmark_group("short");
+            group.bench_with_input(
+                BenchmarkId::from_parameter(nclients),
+                &nclients,
+                |b, nclients| {
+                    let redo_work = Arc::new(Request::short_input());
+                    b.iter_custom(|iters| bench_impl(Arc::clone(&redo_work), iters, *nclients));
+                },
+            );
+        }
+    }

-fn redo_scenarios(c: &mut Criterion) {
-    // logging should be enabled when adding more inputs, since walredo will only report malformed
-    // input to the stderr.
-    // utils::logging::init(utils::logging::LogFormat::Plain).unwrap();
+    {
+        let nclients = [1, 2, 4, 8, 16, 32, 64, 128];
+        for nclients in nclients {
+            let mut group = c.benchmark_group("medium");
+            group.bench_with_input(
+                BenchmarkId::from_parameter(nclients),
+                &nclients,
+                |b, nclients| {
+                    let redo_work = Arc::new(Request::medium_input());
+                    b.iter_custom(|iters| bench_impl(Arc::clone(&redo_work), iters, *nclients));
+                },
+            );
+        }
+    }
+}
+criterion::criterion_group!(benches, bench);
+criterion::criterion_main!(benches);

+// Returns the sum of each client's wall-clock time spent executing their share of the n_redos.
+fn bench_impl(redo_work: Arc<Request>, n_redos: u64, nclients: u64) -> Duration {
    let repo_dir = camino_tempfile::tempdir_in(env!("CARGO_TARGET_TMPDIR")).unwrap();

    let conf = PageServerConf::dummy_conf(repo_dir.path().to_path_buf());
    let conf = Box::leak(Box::new(conf));
    let tenant_shard_id = TenantShardId::unsharded(TenantId::generate());

-    let manager = PostgresRedoManager::new(conf, tenant_shard_id);
-
-    let manager = Arc::new(manager);
-
-    {
-        let rt = tokio::runtime::Builder::new_current_thread()
-            .enable_all()
-            .build()
-            .unwrap();
-        tracing::info!("executing first");
-        rt.block_on(short().execute(&manager)).unwrap();
-        tracing::info!("first executed");
-    }
-
-    let thread_counts = [1, 2, 4, 8, 16, 32, 64, 128];
-
-    let mut group = c.benchmark_group("short");
-    group.sampling_mode(criterion::SamplingMode::Flat);
-
-    for thread_count in thread_counts {
-        group.bench_with_input(
-            BenchmarkId::new("short", thread_count),
-            &thread_count,
-            |b, thread_count| {
-                add_multithreaded_walredo_requesters(b, *thread_count, &manager, short);
-            },
-        );
-    }
-    drop(group);
-
-    let mut group = c.benchmark_group("medium");
-    group.sampling_mode(criterion::SamplingMode::Flat);
-
-    for thread_count in thread_counts {
-        group.bench_with_input(
-            BenchmarkId::new("medium", thread_count),
-            &thread_count,
-            |b, thread_count| {
-                add_multithreaded_walredo_requesters(b, *thread_count, &manager, medium);
-            },
-        );
-    }
-    drop(group);
-}
-
-/// Sets up a multi-threaded tokio runtime with default worker thread count,
-/// then, spawn `requesters` tasks that repeatedly:
-/// - get input from `input_factor()`
-/// - call `manager.request_redo()` with their input
-///
-/// This stress-tests the scalability of a single walredo manager at high tokio-level concurrency.
-///
-/// Using tokio's default worker thread count means the results will differ on machines
-/// with different core countrs. We don't care about that, the performance will always
-/// be different on different hardware. To compare performance of different software versions,
-/// use the same hardware.
-fn add_multithreaded_walredo_requesters(
-    b: &mut criterion::Bencher,
-    nrequesters: usize,
-    manager: &Arc<PostgresRedoManager>,
-    input_factory: fn() -> Request,
-) {
-    assert_ne!(nrequesters, 0);
-
    let rt = tokio::runtime::Builder::new_multi_thread()
        .enable_all()
        .build()
        .unwrap();

-    let barrier = Arc::new(tokio::sync::Barrier::new(nrequesters + 1));
+    let start = Arc::new(Barrier::new(nclients as usize));

-    let mut requesters = JoinSet::new();
-    for _ in 0..nrequesters {
-        let _entered = rt.enter();
-        let manager = manager.clone();
-        let barrier = barrier.clone();
-        requesters.spawn(async move {
-            loop {
-                let input = input_factory();
-                barrier.wait().await;
-                let page = input.execute(&manager).await.unwrap();
-                assert_eq!(page.remaining(), 8192);
-                barrier.wait().await;
-            }
+    let mut tasks = JoinSet::new();
+
+    let manager = PostgresRedoManager::new(conf, tenant_shard_id);
+    let manager = Arc::new(manager);
+
+    for _ in 0..nclients {
+        rt.block_on(async {
+            tasks.spawn(client(
+                Arc::clone(&manager),
+                Arc::clone(&start),
+                Arc::clone(&redo_work),
+                // divide the amount of work equally among the clients
+                n_redos / nclients,
+            ))
        });
    }

-    let do_one_iteration = || {
-        rt.block_on(async {
-            barrier.wait().await;
-            // wait for work to complete
-            barrier.wait().await;
-        })
-    };
-
-    b.iter_batched(
-        || {
-            // warmup
-            do_one_iteration();
-        },
-        |()| {
-            // work loop
-            do_one_iteration();
-        },
-        criterion::BatchSize::PerIteration,
-    );
-
-    rt.block_on(requesters.shutdown());
+    rt.block_on(async move {
+        let mut total_wallclock_time = std::time::Duration::from_millis(0);
+        while let Some(res) = tasks.join_next().await {
+            total_wallclock_time += res.unwrap();
+        }
+        total_wallclock_time
+    })
 }

-criterion_group!(benches, redo_scenarios);
-criterion_main!(benches);
+async fn client(
+    mgr: Arc<PostgresRedoManager>,
+    start: Arc<Barrier>,
+    redo_work: Arc<Request>,
+    n_redos: u64,
+) -> Duration {
+    start.wait().await;
+    let start = Instant::now();
+    for _ in 0..n_redos {
+        let page = redo_work.execute(&mgr).await.unwrap();
+        assert_eq!(page.remaining(), 8192);
+        // The real pageserver will rarely if ever do 2 walredos in a row without
+        // yielding to the executor.
+        tokio::task::yield_now().await;
+    }
+    start.elapsed()
+}

 macro_rules! lsn {
    ($input:expr) => {{
@@ -166,12 +162,46 @@ macro_rules! lsn {
    }};
 }

-/// Short payload, 1132 bytes.
-// pg_records are copypasted from log, where they are put with Debug impl of Bytes, which uses \0
-// for null bytes.
-#[allow(clippy::octal_escapes)]
-fn short() -> Request {
-    Request {
+/// Simple wrapper around `WalRedoManager::request_redo`.
+///
+/// In benchmarks this is cloned around.
+#[derive(Clone)]
+struct Request {
+    key: Key,
+    lsn: Lsn,
+    base_img: Option<(Lsn, Bytes)>,
+    records: Vec<(Lsn, NeonWalRecord)>,
+    pg_version: u32,
+}
+
+impl Request {
+    async fn execute(&self, manager: &PostgresRedoManager) -> anyhow::Result<Bytes> {
+        let Request {
+            key,
+            lsn,
+            base_img,
+            records,
+            pg_version,
+        } = self;
+
+        // TODO: avoid these clones
+        manager
+            .request_redo(*key, *lsn, base_img.clone(), records.clone(), *pg_version)
+            .await
+    }
+
+    fn pg_record(will_init: bool, bytes: &'static [u8]) -> NeonWalRecord {
+        let rec = Bytes::from_static(bytes);
+        NeonWalRecord::Postgres { will_init, rec }
+    }
+
+    /// Short payload, 1132 bytes.
+    // pg_records are copypasted from log, where they are put with Debug impl of Bytes, which uses \0
+    // for null bytes.
+    #[allow(clippy::octal_escapes)]
+    pub fn short_input() -> Request {
+        let pg_record = Self::pg_record;
+        Request {
        key: Key {
            field1: 0,
            field2: 1663,
@@ -194,13 +224,14 @@ fn short() -> Request {
        ],
        pg_version: 14,
    }
-}
+    }

-/// Medium sized payload, serializes as 26393 bytes.
-// see [`short`]
-#[allow(clippy::octal_escapes)]
-fn medium() -> Request {
-    Request {
+    /// Medium sized payload, serializes as 26393 bytes.
+    // see [`short`]
+    #[allow(clippy::octal_escapes)]
+    pub fn medium_input() -> Request {
+        let pg_record = Self::pg_record;
+        Request {
        key: Key {
            field1: 0,
            field2: 1663,
@@ -442,37 +473,5 @@ fn medium() -> Request {
        ],
        pg_version: 14,
    }
-}
-
-fn pg_record(will_init: bool, bytes: &'static [u8]) -> NeonWalRecord {
-    let rec = Bytes::from_static(bytes);
-    NeonWalRecord::Postgres { will_init, rec }
-}
-
-/// Simple wrapper around `WalRedoManager::request_redo`.
-///
-/// In benchmarks this is cloned around.
-#[derive(Clone)]
-struct Request {
-    key: Key,
-    lsn: Lsn,
-    base_img: Option<(Lsn, Bytes)>,
-    records: Vec<(Lsn, NeonWalRecord)>,
-    pg_version: u32,
-}
-
-impl Request {
-    async fn execute(self, manager: &PostgresRedoManager) -> anyhow::Result<Bytes> {
-        let Request {
-            key,
-            lsn,
-            base_img,
-            records,
-            pg_version,
-        } = self;
-
-        manager
-            .request_redo(key, lsn, base_img, records, pg_version)
-            .await
    }
 }
@@ -128,12 +128,12 @@ impl Client {

    pub async fn timeline_info(
        &self,
-        tenant_id: TenantId,
+        tenant_shard_id: TenantShardId,
        timeline_id: TimelineId,
        force_await_logical_size: ForceAwaitLogicalSize,
    ) -> Result<pageserver_api::models::TimelineInfo> {
        let uri = format!(
-            "{}/v1/tenant/{tenant_id}/timeline/{timeline_id}",
+            "{}/v1/tenant/{tenant_shard_id}/timeline/{timeline_id}",
            self.mgmt_api_endpoint
        );

@@ -151,11 +151,11 @@ impl Client {

    pub async fn keyspace(
        &self,
-        tenant_id: TenantId,
+        tenant_shard_id: TenantShardId,
        timeline_id: TimelineId,
    ) -> Result<pageserver_api::models::partitioning::Partitioning> {
        let uri = format!(
-            "{}/v1/tenant/{tenant_id}/timeline/{timeline_id}/keyspace",
+            "{}/v1/tenant/{tenant_shard_id}/timeline/{timeline_id}/keyspace",
            self.mgmt_api_endpoint
        );
        self.get(&uri)
@@ -43,7 +43,8 @@ pub async fn compact_tiered<E: CompactionJobExecutor>(
    fanout: u64,
    ctx: &E::RequestContext,
 ) -> anyhow::Result<()> {
-    assert!(fanout >= 2);
+    assert!(fanout >= 1, "fanout needs to be at least 1 but is {fanout}");
+    let exp_base = fanout.max(2);
    // Start at L0
    let mut current_level_no = 0;
    let mut current_level_target_height = target_file_size;
@@ -106,7 +107,7 @@ pub async fn compact_tiered<E: CompactionJobExecutor>(
            break;
        }
        current_level_no += 1;
-        current_level_target_height = current_level_target_height.saturating_mul(fanout);
+        current_level_target_height = current_level_target_height.saturating_mul(exp_base);
    }
    Ok(())
 }
@@ -1,4 +1,5 @@
 use anyhow::Context;
+use pageserver_api::shard::TenantShardId;
 use pageserver_client::mgmt_api::ForceAwaitLogicalSize;
 use pageserver_client::page_service::BasebackupRequest;

@@ -95,7 +96,7 @@ async fn main_impl(
            let timeline = *timeline;
            let info = mgmt_api_client
                .timeline_info(
-                    timeline.tenant_id,
+                    TenantShardId::unsharded(timeline.tenant_id),
                    timeline.timeline_id,
                    ForceAwaitLogicalSize::No,
                )
@@ -4,6 +4,7 @@ use pageserver_api::key::{is_rel_block_key, key_to_rel_block, Key};
 use pageserver_api::keyspace::KeySpaceAccum;
 use pageserver_api::models::PagestreamGetPageRequest;

+use pageserver_api::shard::TenantShardId;
 use tokio_util::sync::CancellationToken;
 use utils::id::TenantTimelineId;
 use utils::lsn::Lsn;
@@ -173,7 +174,10 @@ async fn main_impl(
                let timeline = *timeline;
                async move {
                    let partitioning = mgmt_api_client
-                        .keyspace(timeline.tenant_id, timeline.timeline_id)
+                        .keyspace(
+                            TenantShardId::unsharded(timeline.tenant_id),
+                            timeline.timeline_id,
+                        )
                        .await?;
                    let lsn = partitioning.at_lsn;
                    let start = Instant::now();
@@ -1,6 +1,7 @@
 use std::sync::Arc;

 use humantime::Duration;
+use pageserver_api::shard::TenantShardId;
 use tokio::task::JoinSet;
 use utils::id::TenantTimelineId;

@@ -59,7 +60,11 @@ async fn main_impl(args: Args) -> anyhow::Result<()> {
        let mgmt_api_client = Arc::clone(&mgmt_api_client);
        js.spawn(async move {
            let info = mgmt_api_client
-                .timeline_info(tl.tenant_id, tl.timeline_id, ForceAwaitLogicalSize::Yes)
+                .timeline_info(
+                    TenantShardId::unsharded(tl.tenant_id),
+                    tl.timeline_id,
+                    ForceAwaitLogicalSize::Yes,
+                )
                .await
                .unwrap();

@@ -74,7 +79,11 @@ async fn main_impl(args: Args) -> anyhow::Result<()> {
                while !info.current_logical_size_is_accurate {
                    ticker.tick().await;
                    info = mgmt_api_client
-                        .timeline_info(tl.tenant_id, tl.timeline_id, ForceAwaitLogicalSize::Yes)
+                        .timeline_info(
+                            TenantShardId::unsharded(tl.tenant_id),
+                            tl.timeline_id,
+                            ForceAwaitLogicalSize::Yes,
+                        )
                        .await
                        .unwrap();
                }
@@ -18,6 +18,7 @@ use pageserver::metrics::{STARTUP_DURATION, STARTUP_IS_LOADING};
 use pageserver::task_mgr::WALRECEIVER_RUNTIME;
 use pageserver::tenant::{secondary, TenantSharedResources};
 use remote_storage::GenericRemoteStorage;
+use tokio::signal::unix::SignalKind;
 use tokio::time::Instant;
 use tracing::*;

@@ -600,32 +601,37 @@ fn start_pageserver(
            None,
            "consumption metrics collection",
            true,
-            async move {
-                // first wait until background jobs are cleared to launch.
-                //
-                // this is because we only process active tenants and timelines, and the
-                // Timeline::get_current_logical_size will spawn the logical size calculation,
-                // which will not be rate-limited.
-                let cancel = task_mgr::shutdown_token();
+            {
+                let tenant_manager = tenant_manager.clone();
+                async move {
+                    // first wait until background jobs are cleared to launch.
+                    //
+                    // this is because we only process active tenants and timelines, and the
+                    // Timeline::get_current_logical_size will spawn the logical size calculation,
+                    // which will not be rate-limited.
+                    let cancel = task_mgr::shutdown_token();

-                tokio::select! {
-                    _ = cancel.cancelled() => { return Ok(()); },
-                    _ = background_jobs_barrier.wait() => {}
-                };
+                    tokio::select! {
+                        _ = cancel.cancelled() => { return Ok(()); },
+                        _ = background_jobs_barrier.wait() => {}
+                    };

-                pageserver::consumption_metrics::collect_metrics(
-                    metric_collection_endpoint,
-                    conf.metric_collection_interval,
-                    conf.cached_metric_collection_interval,
-                    conf.synthetic_size_calculation_interval,
-                    conf.id,
-                    local_disk_storage,
-                    cancel,
-                    metrics_ctx,
-                )
-                .instrument(info_span!("metrics_collection"))
-                .await?;
-                Ok(())
+                    pageserver::consumption_metrics::collect_metrics(
+                        tenant_manager,
+                        metric_collection_endpoint,
+                        &conf.metric_collection_bucket,
+                        conf.metric_collection_interval,
+                        conf.cached_metric_collection_interval,
+                        conf.synthetic_size_calculation_interval,
+                        conf.id,
+                        local_disk_storage,
+                        cancel,
+                        metrics_ctx,
+                    )
+                    .instrument(info_span!("metrics_collection"))
+                    .await?;
+                    Ok(())
+                }
            },
        );
    }
@@ -666,42 +672,37 @@ fn start_pageserver(
    let mut shutdown_pageserver = Some(shutdown_pageserver.drop_guard());

    // All started up! Now just sit and wait for shutdown signal.
-    {
-        use signal_hook::consts::*;
-        let signal_handler = BACKGROUND_RUNTIME.spawn_blocking(move || {
-            let mut signals =
-                signal_hook::iterator::Signals::new([SIGINT, SIGTERM, SIGQUIT]).unwrap();
-            return signals
-                .forever()
-                .next()
-                .expect("forever() never returns None unless explicitly closed");
-        });
-        let signal = BACKGROUND_RUNTIME
-            .block_on(signal_handler)
-            .expect("join error");
-        match signal {
-            SIGQUIT => {
-                info!("Got signal {signal}. Terminating in immediate shutdown mode",);
-                std::process::exit(111);
-            }
-            SIGINT | SIGTERM => {
-                info!("Got signal {signal}. Terminating gracefully in fast shutdown mode",);

-                // This cancels the `shutdown_pageserver` cancellation tree.
-                // Right now that tree doesn't reach very far, and `task_mgr` is used instead.
-                // The plan is to change that over time.
-                shutdown_pageserver.take();
-                let bg_remote_storage = remote_storage.clone();
-                let bg_deletion_queue = deletion_queue.clone();
-                BACKGROUND_RUNTIME.block_on(pageserver::shutdown_pageserver(
-                    &tenant_manager,
-                    bg_remote_storage.map(|_| bg_deletion_queue),
-                    0,
-                ));
-                unreachable!()
-            }
-            _ => unreachable!(),
-        }
+    {
+        BACKGROUND_RUNTIME.block_on(async move {
+            let mut sigint = tokio::signal::unix::signal(SignalKind::interrupt()).unwrap();
+            let mut sigterm = tokio::signal::unix::signal(SignalKind::terminate()).unwrap();
+            let mut sigquit = tokio::signal::unix::signal(SignalKind::quit()).unwrap();
+            let signal = tokio::select! {
+                _ = sigquit.recv() => {
+                    info!("Got signal SIGQUIT. Terminating in immediate shutdown mode",);
+                    std::process::exit(111);
+                }
+                _ = sigint.recv() => { "SIGINT" },
+                _ = sigterm.recv() => { "SIGTERM" },
+            };
+
+            info!("Got signal {signal}. Terminating gracefully in fast shutdown mode",);
+
+            // This cancels the `shutdown_pageserver` cancellation tree.
+            // Right now that tree doesn't reach very far, and `task_mgr` is used instead.
+            // The plan is to change that over time.
+            shutdown_pageserver.take();
+            let bg_remote_storage = remote_storage.clone();
+            let bg_deletion_queue = deletion_queue.clone();
+            pageserver::shutdown_pageserver(
+                &tenant_manager,
+                bg_remote_storage.map(|_| bg_deletion_queue),
+                0,
+            )
+            .await;
+            unreachable!()
+        })
    }
 }

@@ -95,6 +95,8 @@ pub mod defaults {

    pub const DEFAULT_VALIDATE_VECTORED_GET: bool = true;

+    pub const DEFAULT_EPHEMERAL_BYTES_PER_MEMORY_KB: usize = 0;
+
    ///
    /// Default built-in configuration file.
    ///
@@ -156,6 +158,8 @@ pub mod defaults {
 #heatmap_upload_concurrency = {DEFAULT_HEATMAP_UPLOAD_CONCURRENCY}
 #secondary_download_concurrency = {DEFAULT_SECONDARY_DOWNLOAD_CONCURRENCY}

+#ephemeral_bytes_per_memory_kb = {DEFAULT_EPHEMERAL_BYTES_PER_MEMORY_KB}
+
 [remote_storage]

 "#
@@ -234,6 +238,7 @@ pub struct PageServerConf {
    // How often to send unchanged cached metrics to the metrics endpoint.
    pub cached_metric_collection_interval: Duration,
    pub metric_collection_endpoint: Option<Url>,
+    pub metric_collection_bucket: Option<RemoteStorageConfig>,
    pub synthetic_size_calculation_interval: Duration,

    pub disk_usage_based_eviction: Option<DiskUsageEvictionTaskConfig>,
@@ -278,6 +283,13 @@ pub struct PageServerConf {
    pub max_vectored_read_bytes: MaxVectoredReadBytes,

    pub validate_vectored_get: bool,
+
+    /// 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,
 }

 /// We do not want to store this in a PageServerConf because the latter may be logged
@@ -373,6 +385,7 @@ struct PageServerConfigBuilder {
    cached_metric_collection_interval: BuilderValue<Duration>,
    metric_collection_endpoint: BuilderValue<Option<Url>>,
    synthetic_size_calculation_interval: BuilderValue<Duration>,
+    metric_collection_bucket: BuilderValue<Option<RemoteStorageConfig>>,

    disk_usage_based_eviction: BuilderValue<Option<DiskUsageEvictionTaskConfig>>,

@@ -398,6 +411,8 @@ struct PageServerConfigBuilder {
    max_vectored_read_bytes: BuilderValue<MaxVectoredReadBytes>,

    validate_vectored_get: BuilderValue<bool>,
+
+    ephemeral_bytes_per_memory_kb: BuilderValue<usize>,
 }

 impl PageServerConfigBuilder {
@@ -455,6 +470,8 @@ impl PageServerConfigBuilder {
            .expect("cannot parse default synthetic size calculation interval")),
            metric_collection_endpoint: Set(DEFAULT_METRIC_COLLECTION_ENDPOINT),

+            metric_collection_bucket: Set(None),
+
            disk_usage_based_eviction: Set(None),

            test_remote_failures: Set(0),
@@ -482,6 +499,7 @@ impl PageServerConfigBuilder {
                NonZeroUsize::new(DEFAULT_MAX_VECTORED_READ_BYTES).unwrap(),
            )),
            validate_vectored_get: Set(DEFAULT_VALIDATE_VECTORED_GET),
+            ephemeral_bytes_per_memory_kb: Set(DEFAULT_EPHEMERAL_BYTES_PER_MEMORY_KB),
        }
    }
 }
@@ -586,6 +604,13 @@ impl PageServerConfigBuilder {
        self.metric_collection_endpoint = BuilderValue::Set(metric_collection_endpoint)
    }

+    pub fn metric_collection_bucket(
+        &mut self,
+        metric_collection_bucket: Option<RemoteStorageConfig>,
+    ) {
+        self.metric_collection_bucket = BuilderValue::Set(metric_collection_bucket)
+    }
+
    pub fn synthetic_size_calculation_interval(
        &mut self,
        synthetic_size_calculation_interval: Duration,
@@ -654,6 +679,10 @@ impl PageServerConfigBuilder {
        self.validate_vectored_get = 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 build(self) -> anyhow::Result<PageServerConf> {
        let default = Self::default_values();

@@ -694,6 +723,7 @@ impl PageServerConfigBuilder {
                metric_collection_interval,
                cached_metric_collection_interval,
                metric_collection_endpoint,
+                metric_collection_bucket,
                synthetic_size_calculation_interval,
                disk_usage_based_eviction,
                test_remote_failures,
@@ -708,6 +738,7 @@ impl PageServerConfigBuilder {
                get_vectored_impl,
                max_vectored_read_bytes,
                validate_vectored_get,
+                ephemeral_bytes_per_memory_kb,
            }
            CUSTOM LOGIC
            {
@@ -942,6 +973,9 @@ impl PageServerConf {
                    let endpoint = parse_toml_string(key, item)?.parse().context("failed to parse metric_collection_endpoint")?;
                    builder.metric_collection_endpoint(Some(endpoint));
                },
+                "metric_collection_bucket" => {
+                    builder.metric_collection_bucket(RemoteStorageConfig::from_toml(item)?)
+                }
                "synthetic_size_calculation_interval" =>
                    builder.synthetic_size_calculation_interval(parse_toml_duration(key, item)?),
                "test_remote_failures" => builder.test_remote_failures(parse_toml_u64(key, item)?),
@@ -995,6 +1029,9 @@ impl PageServerConf {
                "validate_vectored_get" => {
                    builder.get_validate_vectored_get(parse_toml_bool("validate_vectored_get", item)?)
                }
+                "ephemeral_bytes_per_memory_kb" => {
+                    builder.get_ephemeral_bytes_per_memory_kb(parse_toml_u64("ephemeral_bytes_per_memory_kb", item)? as usize)
+                }
                _ => bail!("unrecognized pageserver option '{key}'"),
            }
        }
@@ -1057,6 +1094,7 @@ impl PageServerConf {
            metric_collection_interval: Duration::from_secs(60),
            cached_metric_collection_interval: Duration::from_secs(60 * 60),
            metric_collection_endpoint: defaults::DEFAULT_METRIC_COLLECTION_ENDPOINT,
+            metric_collection_bucket: None,
            synthetic_size_calculation_interval: Duration::from_secs(60),
            disk_usage_based_eviction: None,
            test_remote_failures: 0,
@@ -1075,6 +1113,7 @@ impl PageServerConf {
                    .expect("Invalid default constant"),
            ),
            validate_vectored_get: defaults::DEFAULT_VALIDATE_VECTORED_GET,
+            ephemeral_bytes_per_memory_kb: defaults::DEFAULT_EPHEMERAL_BYTES_PER_MEMORY_KB,
        }
    }
 }
@@ -1289,6 +1328,7 @@ background_task_maximum_delay = '334 s'
                    defaults::DEFAULT_CACHED_METRIC_COLLECTION_INTERVAL
                )?,
                metric_collection_endpoint: defaults::DEFAULT_METRIC_COLLECTION_ENDPOINT,
+                metric_collection_bucket: None,
                synthetic_size_calculation_interval: humantime::parse_duration(
                    defaults::DEFAULT_SYNTHETIC_SIZE_CALCULATION_INTERVAL
                )?,
@@ -1311,6 +1351,7 @@ background_task_maximum_delay = '334 s'
                        .expect("Invalid default constant")
                ),
                validate_vectored_get: defaults::DEFAULT_VALIDATE_VECTORED_GET,
+                ephemeral_bytes_per_memory_kb: defaults::DEFAULT_EPHEMERAL_BYTES_PER_MEMORY_KB
            },
            "Correct defaults should be used when no config values are provided"
        );
@@ -1363,6 +1404,7 @@ background_task_maximum_delay = '334 s'
                metric_collection_interval: Duration::from_secs(222),
                cached_metric_collection_interval: Duration::from_secs(22200),
                metric_collection_endpoint: Some(Url::parse("http://localhost:80/metrics")?),
+                metric_collection_bucket: None,
                synthetic_size_calculation_interval: Duration::from_secs(333),
                disk_usage_based_eviction: None,
                test_remote_failures: 0,
@@ -1381,6 +1423,7 @@ background_task_maximum_delay = '334 s'
                        .expect("Invalid default constant")
                ),
                validate_vectored_get: defaults::DEFAULT_VALIDATE_VECTORED_GET,
+                ephemeral_bytes_per_memory_kb: defaults::DEFAULT_EPHEMERAL_BYTES_PER_MEMORY_KB
            },
            "Should be able to parse all basic config values correctly"
        );
@@ -3,10 +3,13 @@
 use crate::context::{DownloadBehavior, RequestContext};
 use crate::task_mgr::{self, TaskKind, BACKGROUND_RUNTIME};
 use crate::tenant::tasks::BackgroundLoopKind;
-use crate::tenant::{mgr, LogicalSizeCalculationCause, PageReconstructError, Tenant};
+use crate::tenant::{
+    mgr::TenantManager, LogicalSizeCalculationCause, PageReconstructError, Tenant,
+};
 use camino::Utf8PathBuf;
 use consumption_metrics::EventType;
 use pageserver_api::models::TenantState;
+use remote_storage::{GenericRemoteStorage, RemoteStorageConfig};
 use reqwest::Url;
 use std::collections::HashMap;
 use std::sync::Arc;
@@ -40,7 +43,9 @@ type Cache = HashMap<MetricsKey, (EventType, u64)>;
 /// Main thread that serves metrics collection
 #[allow(clippy::too_many_arguments)]
 pub async fn collect_metrics(
+    tenant_manager: Arc<TenantManager>,
    metric_collection_endpoint: &Url,
+    metric_collection_bucket: &Option<RemoteStorageConfig>,
    metric_collection_interval: Duration,
    _cached_metric_collection_interval: Duration,
    synthetic_size_calculation_interval: Duration,
@@ -65,15 +70,19 @@ pub async fn collect_metrics(
        None,
        "synthetic size calculation",
        false,
-        async move {
-            calculate_synthetic_size_worker(
-                synthetic_size_calculation_interval,
-                &cancel,
-                &worker_ctx,
-            )
-            .instrument(info_span!("synthetic_size_worker"))
-            .await?;
-            Ok(())
+        {
+            let tenant_manager = tenant_manager.clone();
+            async move {
+                calculate_synthetic_size_worker(
+                    tenant_manager,
+                    synthetic_size_calculation_interval,
+                    &cancel,
+                    &worker_ctx,
+                )
+                .instrument(info_span!("synthetic_size_worker"))
+                .await?;
+                Ok(())
+            }
        },
    );

@@ -94,13 +103,27 @@ pub async fn collect_metrics(
        .build()
        .expect("Failed to create http client with timeout");

+    let bucket_client = if let Some(bucket_config) = metric_collection_bucket {
+        match GenericRemoteStorage::from_config(bucket_config) {
+            Ok(client) => Some(client),
+            Err(e) => {
+                // Non-fatal error: if we were given an invalid config, we will proceed
+                // with sending metrics over the network, but not to S3.
+                tracing::warn!("Invalid configuration for metric_collection_bucket: {e}");
+                None
+            }
+        }
+    } else {
+        None
+    };
+
    let node_id = node_id.to_string();

    loop {
        let started_at = Instant::now();

        // these are point in time, with variable "now"
-        let metrics = metrics::collect_all_metrics(&cached_metrics, &ctx).await;
+        let metrics = metrics::collect_all_metrics(&tenant_manager, &cached_metrics, &ctx).await;

        let metrics = Arc::new(metrics);

@@ -118,10 +141,18 @@ pub async fn collect_metrics(
                    tracing::error!("failed to persist metrics to {path:?}: {e:#}");
                }
            }
+
+            if let Some(bucket_client) = &bucket_client {
+                let res =
+                    upload::upload_metrics_bucket(bucket_client, &cancel, &node_id, &metrics).await;
+                if let Err(e) = res {
+                    tracing::error!("failed to upload to S3: {e:#}");
+                }
+            }
        };

        let upload = async {
-            let res = upload::upload_metrics(
+            let res = upload::upload_metrics_http(
                &client,
                metric_collection_endpoint,
                &cancel,
@@ -132,7 +163,7 @@ pub async fn collect_metrics(
            .await;
            if let Err(e) = res {
                // serialization error which should never happen
-                tracing::error!("failed to upload due to {e:#}");
+                tracing::error!("failed to upload via HTTP due to {e:#}");
            }
        };

@@ -247,6 +278,7 @@ async fn reschedule(

 /// Caclculate synthetic size for each active tenant
 async fn calculate_synthetic_size_worker(
+    tenant_manager: Arc<TenantManager>,
    synthetic_size_calculation_interval: Duration,
    cancel: &CancellationToken,
    ctx: &RequestContext,
@@ -259,7 +291,7 @@ async fn calculate_synthetic_size_worker(
    loop {
        let started_at = Instant::now();

-        let tenants = match mgr::list_tenants().await {
+        let tenants = match tenant_manager.list_tenants() {
            Ok(tenants) => tenants,
            Err(e) => {
                warn!("cannot get tenant list: {e:#}");
@@ -278,10 +310,14 @@ async fn calculate_synthetic_size_worker(
                continue;
            }

-            let Ok(tenant) = mgr::get_tenant(tenant_shard_id, true) else {
+            let Ok(tenant) = tenant_manager.get_attached_tenant_shard(tenant_shard_id) else {
                continue;
            };

+            if !tenant.is_active() {
+                continue;
+            }
+
            // there is never any reason to exit calculate_synthetic_size_worker following any
            // return value -- we don't need to care about shutdown because no tenant is found when
            // pageserver is shut down.
@@ -319,9 +355,7 @@ async fn calculate_and_log(tenant: &Tenant, cancel: &CancellationToken, ctx: &Re
    };

    // this error can be returned if timeline is shutting down, but it does not
-    // mean the synthetic size worker should terminate. we do not need any checks
-    // in this function because `mgr::get_tenant` will error out after shutdown has
-    // progressed to shutting down tenants.
+    // mean the synthetic size worker should terminate.
    let shutting_down = matches!(
        e.downcast_ref::<PageReconstructError>(),
        Some(PageReconstructError::Cancelled | PageReconstructError::AncestorStopping(_))
@@ -1,3 +1,4 @@
+use crate::tenant::mgr::TenantManager;
 use crate::{context::RequestContext, tenant::timeline::logical_size::CurrentLogicalSize};
 use chrono::{DateTime, Utc};
 use consumption_metrics::EventType;
@@ -181,6 +182,7 @@ impl MetricsKey {
 }

 pub(super) async fn collect_all_metrics(
+    tenant_manager: &Arc<TenantManager>,
    cached_metrics: &Cache,
    ctx: &RequestContext,
 ) -> Vec<RawMetric> {
@@ -188,7 +190,7 @@ pub(super) async fn collect_all_metrics(

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

-    let tenants = match crate::tenant::mgr::list_tenants().await {
+    let tenants = match tenant_manager.list_tenants() {
        Ok(tenants) => tenants,
        Err(err) => {
            tracing::error!("failed to list tenants: {:?}", err);
@@ -200,7 +202,8 @@ pub(super) async fn collect_all_metrics(
        if state != TenantState::Active || !id.is_zero() {
            None
        } else {
-            crate::tenant::mgr::get_tenant(id, true)
+            tenant_manager
+                .get_attached_tenant_shard(id)
                .ok()
                .map(|tenant| (id.tenant_id, tenant))
        }
@@ -1,4 +1,9 @@
+use std::time::SystemTime;
+
+use chrono::{DateTime, Utc};
 use consumption_metrics::{Event, EventChunk, IdempotencyKey, CHUNK_SIZE};
+use remote_storage::{GenericRemoteStorage, RemotePath};
+use tokio::io::AsyncWriteExt;
 use tokio_util::sync::CancellationToken;
 use tracing::Instrument;

@@ -13,8 +18,9 @@ struct Ids {
    pub(super) timeline_id: Option<TimelineId>,
 }

+/// Serialize and write metrics to an HTTP endpoint
 #[tracing::instrument(skip_all, fields(metrics_total = %metrics.len()))]
-pub(super) async fn upload_metrics(
+pub(super) async fn upload_metrics_http(
    client: &reqwest::Client,
    metric_collection_endpoint: &reqwest::Url,
    cancel: &CancellationToken,
@@ -74,6 +80,60 @@ pub(super) async fn upload_metrics(
    Ok(())
 }

+/// Serialize and write metrics to a remote storage object
+#[tracing::instrument(skip_all, fields(metrics_total = %metrics.len()))]
+pub(super) async fn upload_metrics_bucket(
+    client: &GenericRemoteStorage,
+    cancel: &CancellationToken,
+    node_id: &str,
+    metrics: &[RawMetric],
+) -> anyhow::Result<()> {
+    if metrics.is_empty() {
+        // Skip uploads if we have no metrics, so that readers don't have to handle the edge case
+        // of an empty object.
+        return Ok(());
+    }
+
+    // Compose object path
+    let datetime: DateTime<Utc> = SystemTime::now().into();
+    let ts_prefix = datetime.format("year=%Y/month=%m/day=%d/%H:%M:%SZ");
+    let path = RemotePath::from_string(&format!("{ts_prefix}_{node_id}.ndjson.gz"))?;
+
+    // Set up a gzip writer into a buffer
+    let mut compressed_bytes: Vec<u8> = Vec::new();
+    let compressed_writer = std::io::Cursor::new(&mut compressed_bytes);
+    let mut gzip_writer = async_compression::tokio::write::GzipEncoder::new(compressed_writer);
+
+    // Serialize and write into compressed buffer
+    let started_at = std::time::Instant::now();
+    for res in serialize_in_chunks(CHUNK_SIZE, metrics, node_id) {
+        let (_chunk, body) = res?;
+        gzip_writer.write_all(&body).await?;
+    }
+    gzip_writer.flush().await?;
+    gzip_writer.shutdown().await?;
+    let compressed_length = compressed_bytes.len();
+
+    // Write to remote storage
+    client
+        .upload_storage_object(
+            futures::stream::once(futures::future::ready(Ok(compressed_bytes.into()))),
+            compressed_length,
+            &path,
+            cancel,
+        )
+        .await?;
+    let elapsed = started_at.elapsed();
+
+    tracing::info!(
+        compressed_length,
+        elapsed_ms = elapsed.as_millis(),
+        "write metrics bucket at {path}",
+    );
+
+    Ok(())
+}
+
 // The return type is quite ugly, but we gain testability in isolation
 fn serialize_in_chunks<'a, F>(
    chunk_size: usize,
@@ -5,13 +5,14 @@ use pageserver_api::{
    controller_api::NodeRegisterRequest,
    shard::TenantShardId,
    upcall_api::{
-        ReAttachRequest, ReAttachResponse, ValidateRequest, ValidateRequestTenant, ValidateResponse,
+        ReAttachRequest, ReAttachResponse, ReAttachResponseTenant, ValidateRequest,
+        ValidateRequestTenant, ValidateResponse,
    },
 };
 use serde::{de::DeserializeOwned, Serialize};
 use tokio_util::sync::CancellationToken;
 use url::Url;
-use utils::{backoff, generation::Generation, id::NodeId};
+use utils::{backoff, failpoint_support, generation::Generation, id::NodeId};

 use crate::{
    config::{NodeMetadata, PageServerConf},
@@ -37,7 +38,9 @@ pub trait ControlPlaneGenerationsApi {
    fn re_attach(
        &self,
        conf: &PageServerConf,
-    ) -> impl Future<Output = Result<HashMap<TenantShardId, Generation>, RetryForeverError>> + Send;
+    ) -> impl Future<
+        Output = Result<HashMap<TenantShardId, ReAttachResponseTenant>, RetryForeverError>,
+    > + Send;
    fn validate(
        &self,
        tenants: Vec<(TenantShardId, Generation)>,
@@ -118,7 +121,7 @@ impl ControlPlaneGenerationsApi for ControlPlaneClient {
    async fn re_attach(
        &self,
        conf: &PageServerConf,
-    ) -> Result<HashMap<TenantShardId, Generation>, RetryForeverError> {
+    ) -> Result<HashMap<TenantShardId, ReAttachResponseTenant>, RetryForeverError> {
        let re_attach_path = self
            .base_url
            .join("re-attach")
@@ -181,7 +184,7 @@ impl ControlPlaneGenerationsApi for ControlPlaneClient {
        Ok(response
            .tenants
            .into_iter()
-            .map(|t| (t.id, Generation::new(t.gen)))
+            .map(|rart| (rart.id, rart))
            .collect::<HashMap<_, _>>())
    }

@@ -207,7 +210,10 @@ impl ControlPlaneGenerationsApi for ControlPlaneClient {
                .collect(),
        };

-        fail::fail_point!("control-plane-client-validate");
+        failpoint_support::sleep_millis_async!("control-plane-client-validate-sleep", &self.cancel);
+        if self.cancel.is_cancelled() {
+            return Err(RetryForeverError::ShuttingDown);
+        }

        let response: ValidateResponse = self.retry_http_forever(&re_attach_path, request).await?;

@@ -724,8 +724,8 @@ impl DeletionQueue {
 mod test {
    use camino::Utf8Path;
    use hex_literal::hex;
-    use pageserver_api::shard::ShardIndex;
-    use std::io::ErrorKind;
+    use pageserver_api::{shard::ShardIndex, upcall_api::ReAttachResponseTenant};
+    use std::{io::ErrorKind, time::Duration};
    use tracing::info;

    use remote_storage::{RemoteStorageConfig, RemoteStorageKind};
@@ -834,9 +834,10 @@ mod test {
        async fn re_attach(
            &self,
            _conf: &PageServerConf,
-        ) -> Result<HashMap<TenantShardId, Generation>, RetryForeverError> {
+        ) -> Result<HashMap<TenantShardId, ReAttachResponseTenant>, RetryForeverError> {
            unimplemented!()
        }
+
        async fn validate(
            &self,
            tenants: Vec<(TenantShardId, Generation)>,
@@ -61,7 +61,6 @@ use crate::{
    metrics::disk_usage_based_eviction::METRICS,
    task_mgr::{self, TaskKind, BACKGROUND_RUNTIME},
    tenant::{
-        self,
        mgr::TenantManager,
        remote_timeline_client::LayerFileMetadata,
        secondary::SecondaryTenant,
@@ -814,8 +813,8 @@ async fn collect_eviction_candidates(
    const LOG_DURATION_THRESHOLD: std::time::Duration = std::time::Duration::from_secs(10);

    // get a snapshot of the list of tenants
-    let tenants = tenant::mgr::list_tenants()
-        .await
+    let tenants = tenant_manager
+        .list_tenants()
        .context("get list of tenants")?;

    // TODO: avoid listing every layer in every tenant: this loop can block the executor,
@@ -827,8 +826,12 @@ async fn collect_eviction_candidates(
        if cancel.is_cancelled() {
            return Ok(EvictionCandidates::Cancelled);
        }
-        let tenant = match tenant::mgr::get_tenant(tenant_id, true) {
-            Ok(tenant) => tenant,
+        let tenant = match tenant_manager.get_attached_tenant_shard(tenant_id) {
+            Ok(tenant) if tenant.is_active() => tenant,
+            Ok(_) => {
+                debug!(tenant_id=%tenant_id.tenant_id, shard_id=%tenant_id.shard_slug(), "Tenant shard is not active");
+                continue;
+            }
            Err(e) => {
                // this can happen if tenant has lifecycle transition after we fetched it
                debug!("failed to get tenant: {e:#}");
@@ -1038,7 +1038,7 @@ paths:
                  format: hex
      responses:
        "201":
-          description: TimelineInfo
+          description: Timeline was created, or already existed with matching parameters
          content:
            application/json:
              schema:
@@ -1068,11 +1068,17 @@ paths:
              schema:
                $ref: "#/components/schemas/Error"
        "409":
-          description: Timeline already exists, creation skipped
+          description: Timeline already exists, with different parameters.  Creation cannot proceed.
          content:
            application/json:
              schema:
                $ref: "#/components/schemas/ConflictError"
+        "429":
+          description: A creation request was sent for the same Timeline Id while a creation was already in progress.  Back off and retry.
+          content:
+            application/json:
+              schema:
+                $ref: "#/components/schemas/Error"
        "500":
          description: Generic operation error
          content:
@@ -1623,7 +1629,7 @@ components:
          type: integer
          format: int64
          minimum: 0
-          description: The amount of disk space currently utilized by layer files.
+          description: The amount of disk space currently used.
        free_space_bytes:
          type: integer
          format: int64
@@ -36,6 +36,7 @@ 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};
@@ -48,8 +49,8 @@ use crate::task_mgr::TaskKind;
 use crate::tenant::config::{LocationConf, TenantConfOpt};
 use crate::tenant::mgr::GetActiveTenantError;
 use crate::tenant::mgr::{
-    GetTenantError, SetNewTenantConfigError, TenantManager, TenantMapError, TenantMapInsertError,
-    TenantSlotError, TenantSlotUpsertError, TenantStateError,
+    GetTenantError, TenantManager, TenantMapError, TenantMapInsertError, TenantSlotError,
+    TenantSlotUpsertError, TenantStateError,
 };
 use crate::tenant::mgr::{TenantSlot, UpsertLocationError};
 use crate::tenant::remote_timeline_client;
@@ -248,16 +249,11 @@ impl From<GetTenantError> for ApiError {
    fn from(tse: GetTenantError) -> ApiError {
        match tse {
            GetTenantError::NotFound(tid) => ApiError::NotFound(anyhow!("tenant {}", tid).into()),
-            GetTenantError::Broken(reason) => {
-                ApiError::InternalServerError(anyhow!("tenant is broken: {}", reason))
-            }
            GetTenantError::NotActive(_) => {
                // Why is this not `ApiError::NotFound`?
                // Because we must be careful to never return 404 for a tenant if it does
                // in fact exist locally. If we did, the caller could draw the conclusion
                // that it can attach the tenant to another PS and we'd be in split-brain.
-                //
-                // (We can produce this variant only in `mgr::get_tenant(..., active=true)` calls).
                ApiError::ResourceUnavailable("Tenant not yet active".into())
            }
            GetTenantError::MapState(e) => ApiError::ResourceUnavailable(format!("{e}").into()),
@@ -268,6 +264,9 @@ impl From<GetTenantError> for ApiError {
 impl From<GetActiveTenantError> for ApiError {
    fn from(e: GetActiveTenantError) -> ApiError {
        match e {
+            GetActiveTenantError::Broken(reason) => {
+                ApiError::InternalServerError(anyhow!("tenant is broken: {}", reason))
+            }
            GetActiveTenantError::WillNotBecomeActive(_) => ApiError::Conflict(format!("{}", e)),
            GetActiveTenantError::Cancelled => ApiError::ShuttingDown,
            GetActiveTenantError::NotFound(gte) => gte.into(),
@@ -278,19 +277,6 @@ impl From<GetActiveTenantError> for ApiError {
    }
 }

-impl From<SetNewTenantConfigError> for ApiError {
-    fn from(e: SetNewTenantConfigError) -> ApiError {
-        match e {
-            SetNewTenantConfigError::GetTenant(tid) => {
-                ApiError::NotFound(anyhow!("tenant {}", tid).into())
-            }
-            e @ (SetNewTenantConfigError::Persist(_) | SetNewTenantConfigError::Other(_)) => {
-                ApiError::InternalServerError(anyhow::Error::new(e))
-            }
-        }
-    }
-}
-
 impl From<crate::tenant::DeleteTimelineError> for ApiError {
    fn from(value: crate::tenant::DeleteTimelineError) -> Self {
        use crate::tenant::DeleteTimelineError::*;
@@ -494,7 +480,7 @@ async fn timeline_create_handler(
    async {
        let tenant = state
            .tenant_manager
-            .get_attached_tenant_shard(tenant_shard_id, false)?;
+            .get_attached_tenant_shard(tenant_shard_id)?;

        tenant.wait_to_become_active(ACTIVE_TENANT_TIMEOUT).await?;

@@ -534,10 +520,13 @@ async fn timeline_create_handler(
                    HttpErrorBody::from_msg("Tenant shutting down".to_string()),
                )
            }
-            Err(
-                e @ tenant::CreateTimelineError::Conflict
-                | e @ tenant::CreateTimelineError::AlreadyCreating,
-            ) => json_response(StatusCode::CONFLICT, HttpErrorBody::from_msg(e.to_string())),
+            Err(e @ tenant::CreateTimelineError::Conflict) => {
+                json_response(StatusCode::CONFLICT, HttpErrorBody::from_msg(e.to_string()))
+            }
+            Err(e @ tenant::CreateTimelineError::AlreadyCreating) => json_response(
+                StatusCode::TOO_MANY_REQUESTS,
+                HttpErrorBody::from_msg(e.to_string()),
+            ),
            Err(tenant::CreateTimelineError::AncestorLsn(err)) => json_response(
                StatusCode::NOT_ACCEPTABLE,
                HttpErrorBody::from_msg(format!("{err:#}")),
@@ -580,7 +569,7 @@ async fn timeline_list_handler(
    let response_data = async {
        let tenant = state
            .tenant_manager
-            .get_attached_tenant_shard(tenant_shard_id, false)?;
+            .get_attached_tenant_shard(tenant_shard_id)?;

        tenant.wait_to_become_active(ACTIVE_TENANT_TIMEOUT).await?;

@@ -618,6 +607,7 @@ async fn timeline_preserve_initdb_handler(
    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 state = get_state(&request);

    // Part of the process for disaster recovery from safekeeper-stored WAL:
    // If we don't recover into a new timeline but want to keep the timeline ID,
@@ -625,7 +615,9 @@ async fn timeline_preserve_initdb_handler(
    // location where timeline recreation cand find it.

    async {
-        let tenant = mgr::get_tenant(tenant_shard_id, false)?;
+        let tenant = state
+            .tenant_manager
+            .get_attached_tenant_shard(tenant_shard_id)?;

        let timeline = tenant
            .get_timeline(timeline_id, false)
@@ -667,7 +659,7 @@ async fn timeline_detail_handler(
    let timeline_info = async {
        let tenant = state
            .tenant_manager
-            .get_attached_tenant_shard(tenant_shard_id, false)?;
+            .get_attached_tenant_shard(tenant_shard_id)?;

        tenant.wait_to_become_active(ACTIVE_TENANT_TIMEOUT).await?;

@@ -854,7 +846,7 @@ async fn timeline_delete_handler(

    let tenant = state
        .tenant_manager
-        .get_attached_tenant_shard(tenant_shard_id, false)
+        .get_attached_tenant_shard(tenant_shard_id)
        .map_err(|e| {
            match e {
                // GetTenantError has a built-in conversion to ApiError, but in this context we don't
@@ -972,10 +964,11 @@ async fn tenant_list_handler(
    _cancel: CancellationToken,
 ) -> Result<Response<Body>, ApiError> {
    check_permission(&request, None)?;
+    let state = get_state(&request);

-    let response_data = mgr::list_tenants()
-        .instrument(info_span!("tenant_list"))
-        .await
+    let response_data = state
+        .tenant_manager
+        .list_tenants()
        .map_err(|_| {
            ApiError::ResourceUnavailable("Tenant map is initializing or shutting down".into())
        })?
@@ -998,9 +991,27 @@ async fn tenant_status(
 ) -> Result<Response<Body>, ApiError> {
    let tenant_shard_id: TenantShardId = parse_request_param(&request, "tenant_shard_id")?;
    check_permission(&request, Some(tenant_shard_id.tenant_id))?;
+    let state = get_state(&request);
+
+    // In tests, sometimes we want to query the state of a tenant without auto-activating it if it's currently waiting.
+    let activate = true;
+    #[cfg(feature = "testing")]
+    let activate = parse_query_param(&request, "activate")?.unwrap_or(activate);

    let tenant_info = async {
-        let tenant = mgr::get_tenant(tenant_shard_id, false)?;
+        let tenant = state
+            .tenant_manager
+            .get_attached_tenant_shard(tenant_shard_id)?;
+
+        if activate {
+            // This is advisory: we prefer to let the tenant activate on-demand when this function is
+            // called, but it is still valid to return 200 and describe the current state of the tenant
+            // if it doesn't make it into an active state.
+            tenant
+                .wait_to_become_active(ACTIVE_TENANT_TIMEOUT)
+                .await
+                .ok();
+        }

        // Calculate total physical size of all timelines
        let mut current_physical_size = 0;
@@ -1073,9 +1084,7 @@ async fn tenant_size_handler(
    let inputs_only: Option<bool> = parse_query_param(&request, "inputs_only")?;
    let retention_period: Option<u64> = parse_query_param(&request, "retention_period")?;
    let headers = request.headers();
-
-    let ctx = RequestContext::new(TaskKind::MgmtRequest, DownloadBehavior::Download);
-    let tenant = mgr::get_tenant(tenant_shard_id, true)?;
+    let state = get_state(&request);

    if !tenant_shard_id.is_zero() {
        return Err(ApiError::BadRequest(anyhow!(
@@ -1083,6 +1092,12 @@ async fn tenant_size_handler(
        )));
    }

+    let ctx = RequestContext::new(TaskKind::MgmtRequest, DownloadBehavior::Download);
+    let tenant = state
+        .tenant_manager
+        .get_attached_tenant_shard(tenant_shard_id)?;
+    tenant.wait_to_become_active(ACTIVE_TENANT_TIMEOUT).await?;
+
    // this can be long operation
    let inputs = tenant
        .gather_size_inputs(
@@ -1151,10 +1166,15 @@ async fn tenant_shard_split_handler(
    let state = get_state(&request);
    let ctx = RequestContext::new(TaskKind::MgmtRequest, DownloadBehavior::Warn);

+    let tenant = state
+        .tenant_manager
+        .get_attached_tenant_shard(tenant_shard_id)?;
+    tenant.wait_to_become_active(ACTIVE_TENANT_TIMEOUT).await?;
+
    let new_shards = state
        .tenant_manager
        .shard_split(
-            tenant_shard_id,
+            tenant,
            ShardCount::new(req.new_shard_count),
            req.new_stripe_size,
            &ctx,
@@ -1372,8 +1392,11 @@ async fn get_tenant_config_handler(
 ) -> Result<Response<Body>, ApiError> {
    let tenant_shard_id: TenantShardId = parse_request_param(&request, "tenant_shard_id")?;
    check_permission(&request, Some(tenant_shard_id.tenant_id))?;
+    let state = get_state(&request);

-    let tenant = mgr::get_tenant(tenant_shard_id, false)?;
+    let tenant = state
+        .tenant_manager
+        .get_attached_tenant_shard(tenant_shard_id)?;

    let response = HashMap::from([
        (
@@ -1401,15 +1424,31 @@ async fn update_tenant_config_handler(
    let tenant_id = request_data.tenant_id;
    check_permission(&request, Some(tenant_id))?;

-    let tenant_conf =
+    let new_tenant_conf =
        TenantConfOpt::try_from(&request_data.config).map_err(ApiError::BadRequest)?;

    let state = get_state(&request);
-    state
+
+    let tenant_shard_id = TenantShardId::unsharded(tenant_id);
+
+    let tenant = state
        .tenant_manager
-        .set_new_tenant_config(tenant_conf, tenant_id)
-        .instrument(info_span!("tenant_config", %tenant_id))
-        .await?;
+        .get_attached_tenant_shard(tenant_shard_id)?;
+    tenant.wait_to_become_active(ACTIVE_TENANT_TIMEOUT).await?;
+
+    // This is a legacy API that only operates on attached tenants: the preferred
+    // API to use is the location_config/ endpoint, which lets the caller provide
+    // the full LocationConf.
+    let location_conf = LocationConf::attached_single(
+        new_tenant_conf.clone(),
+        tenant.get_generation(),
+        &ShardParameters::default(),
+    );
+
+    crate::tenant::Tenant::persist_tenant_config(state.conf, &tenant_shard_id, &location_conf)
+        .await
+        .map_err(ApiError::InternalServerError)?;
+    tenant.set_new_tenant_config(new_tenant_conf);

    json_response(StatusCode::OK, ())
 }
@@ -1633,10 +1672,12 @@ async fn handle_tenant_break(
 ) -> Result<Response<Body>, ApiError> {
    let tenant_shard_id: TenantShardId = parse_request_param(&r, "tenant_shard_id")?;

-    let tenant = crate::tenant::mgr::get_tenant(tenant_shard_id, true)
-        .map_err(|_| ApiError::Conflict(String::from("no active tenant found")))?;
-
-    tenant.set_broken("broken from test".to_owned()).await;
+    let state = get_state(&r);
+    state
+        .tenant_manager
+        .get_attached_tenant_shard(tenant_shard_id)?
+        .set_broken("broken from test".to_owned())
+        .await;

    json_response(StatusCode::OK, ())
 }
@@ -1880,7 +1921,7 @@ async fn active_timeline_of_active_tenant(
    tenant_shard_id: TenantShardId,
    timeline_id: TimelineId,
 ) -> Result<Arc<Timeline>, ApiError> {
-    let tenant = tenant_manager.get_attached_tenant_shard(tenant_shard_id, false)?;
+    let tenant = tenant_manager.get_attached_tenant_shard(tenant_shard_id)?;

    tenant.wait_to_become_active(ACTIVE_TENANT_TIMEOUT).await?;

@@ -2266,6 +2307,7 @@ pub fn make_router(

    Ok(router
        .data(state)
+        .get("/metrics", |r| request_span(r, prometheus_metrics_handler))
        .get("/v1/status", |r| api_handler(r, status_handler))
        .put("/v1/failpoints", |r| {
            testing_api_handler("manage failpoints", r, failpoints_handler)
@@ -2,28 +2,21 @@
 //! Import data and WAL from a PostgreSQL data directory and WAL segments into
 //! a neon Timeline.
 //!
-use std::io::SeekFrom;
 use std::path::{Path, PathBuf};

 use anyhow::{bail, ensure, Context, Result};
-use async_compression::tokio::bufread::ZstdDecoder;
-use async_compression::{tokio::write::ZstdEncoder, zstd::CParameter, Level};
 use bytes::Bytes;
 use camino::Utf8Path;
 use futures::StreamExt;
-use nix::NixPath;
-use tokio::fs::{File, OpenOptions};
-use tokio::io::{AsyncBufRead, AsyncRead, AsyncReadExt, AsyncSeekExt, AsyncWriteExt};
+use pageserver_api::key::rel_block_to_key;
+use tokio::io::{AsyncRead, AsyncReadExt};
 use tokio_tar::Archive;
-use tokio_tar::Builder;
-use tokio_tar::HeaderMode;
 use tracing::*;
 use walkdir::WalkDir;

 use crate::context::RequestContext;
 use crate::metrics::WAL_INGEST;
 use crate::pgdatadir_mapping::*;
-use crate::tenant::remote_timeline_client::INITDB_PATH;
 use crate::tenant::Timeline;
 use crate::walingest::WalIngest;
 use crate::walrecord::DecodedWALRecord;
@@ -178,7 +171,10 @@ async fn import_rel(
        let r = reader.read_exact(&mut buf).await;
        match r {
            Ok(_) => {
-                modification.put_rel_page_image(rel, blknum, Bytes::copy_from_slice(&buf))?;
+                let key = rel_block_to_key(rel, blknum);
+                if modification.tline.get_shard_identity().is_key_local(&key) {
+                    modification.put_rel_page_image(rel, blknum, Bytes::copy_from_slice(&buf))?;
+                }
            }

            // TODO: UnexpectedEof is expected
@@ -633,65 +629,3 @@ async fn read_all_bytes(reader: &mut (impl AsyncRead + Unpin)) -> Result<Bytes>
    reader.read_to_end(&mut buf).await?;
    Ok(Bytes::from(buf))
 }
-
-pub async fn create_tar_zst(pgdata_path: &Utf8Path, tmp_path: &Utf8Path) -> Result<(File, u64)> {
-    let file = OpenOptions::new()
-        .create(true)
-        .truncate(true)
-        .read(true)
-        .write(true)
-        .open(&tmp_path)
-        .await
-        .with_context(|| format!("tempfile creation {tmp_path}"))?;
-
-    let mut paths = Vec::new();
-    for entry in WalkDir::new(pgdata_path) {
-        let entry = entry?;
-        let metadata = entry.metadata().expect("error getting dir entry metadata");
-        // Also allow directories so that we also get empty directories
-        if !(metadata.is_file() || metadata.is_dir()) {
-            continue;
-        }
-        let path = entry.into_path();
-        paths.push(path);
-    }
-    // Do a sort to get a more consistent listing
-    paths.sort_unstable();
-    let zstd = ZstdEncoder::with_quality_and_params(
-        file,
-        Level::Default,
-        &[CParameter::enable_long_distance_matching(true)],
-    );
-    let mut builder = Builder::new(zstd);
-    // Use reproducible header mode
-    builder.mode(HeaderMode::Deterministic);
-    for path in paths {
-        let rel_path = path.strip_prefix(pgdata_path)?;
-        if rel_path.is_empty() {
-            // The top directory should not be compressed,
-            // the tar crate doesn't like that
-            continue;
-        }
-        builder.append_path_with_name(&path, rel_path).await?;
-    }
-    let mut zstd = builder.into_inner().await?;
-    zstd.shutdown().await?;
-    let mut compressed = zstd.into_inner();
-    let compressed_len = compressed.metadata().await?.len();
-    const INITDB_TAR_ZST_WARN_LIMIT: u64 = 2 * 1024 * 1024;
-    if compressed_len > INITDB_TAR_ZST_WARN_LIMIT {
-        warn!("compressed {INITDB_PATH} size of {compressed_len} is above limit {INITDB_TAR_ZST_WARN_LIMIT}.");
-    }
-    compressed.seek(SeekFrom::Start(0)).await?;
-    Ok((compressed, compressed_len))
-}
-
-pub async fn extract_tar_zst(
-    pgdata_path: &Utf8Path,
-    tar_zst: impl AsyncBufRead + Unpin,
-) -> Result<()> {
-    let tar = Box::pin(ZstdDecoder::new(tar_zst));
-    let mut archive = Archive::new(tar);
-    archive.unpack(pgdata_path).await?;
-    Ok(())
-}
@@ -435,7 +435,7 @@ pub(crate) static RESIDENT_PHYSICAL_SIZE_GLOBAL: Lazy<UIntGauge> = Lazy::new(||
 static REMOTE_PHYSICAL_SIZE: Lazy<UIntGaugeVec> = Lazy::new(|| {
    register_uint_gauge_vec!(
        "pageserver_remote_physical_size",
-        "The size of the layer files present in the remote storage that are listed in the the remote index_part.json.",
+        "The size of the layer files present in the remote storage that are listed in the remote index_part.json.",
        // Corollary: If any files are missing from the index part, they won't be included here.
        &["tenant_id", "shard_id", "timeline_id"]
    )
@@ -699,6 +699,14 @@ pub static STARTUP_IS_LOADING: Lazy<UIntGauge> = Lazy::new(|| {
    .expect("Failed to register pageserver_startup_is_loading")
 });

+pub(crate) static TIMELINE_EPHEMERAL_BYTES: Lazy<UIntGauge> = Lazy::new(|| {
+    register_uint_gauge!(
+        "pageserver_timeline_ephemeral_bytes",
+        "Total number of bytes in ephemeral layers, summed for all timelines.  Approximate, lazily updated."
+    )
+    .expect("Failed to register metric")
+});
+
 /// Metrics related to the lifecycle of a [`crate::tenant::Tenant`] object: things
 /// like how long it took to load.
 ///
@@ -1475,12 +1483,18 @@ pub(crate) static DELETION_QUEUE: Lazy<DeletionQueueMetrics> = Lazy::new(|| {
 });

 pub(crate) struct WalIngestMetrics {
+    pub(crate) bytes_received: IntCounter,
    pub(crate) records_received: IntCounter,
    pub(crate) records_committed: IntCounter,
    pub(crate) records_filtered: IntCounter,
 }

 pub(crate) static WAL_INGEST: Lazy<WalIngestMetrics> = Lazy::new(|| WalIngestMetrics {
+    bytes_received: register_int_counter!(
+        "pageserver_wal_ingest_bytes_received",
+        "Bytes of WAL ingested from safekeepers",
+    )
+    .unwrap(),
    records_received: register_int_counter!(
        "pageserver_wal_ingest_records_received",
        "Number of WAL records received from safekeepers"
@@ -760,6 +760,7 @@ impl PageServerHandler {
        let mut copyin_reader = pin!(StreamReader::new(self.copyin_stream(pgb, &tenant.cancel)));
        timeline
            .import_basebackup_from_tar(
+                tenant.clone(),
                &mut copyin_reader,
                base_lsn,
                self.broker_client.clone(),
@@ -875,7 +876,13 @@ impl PageServerHandler {
            if lsn <= last_record_lsn {
                lsn = last_record_lsn;
            } else {
-                timeline.wait_lsn(lsn, ctx).await?;
+                timeline
+                    .wait_lsn(
+                        lsn,
+                        crate::tenant::timeline::WaitLsnWaiter::PageService,
+                        ctx,
+                    )
+                    .await?;
                // Since we waited for 'lsn' to arrive, that is now the last
                // record LSN. (Or close enough for our purposes; the
                // last-record LSN can advance immediately after we return
@@ -887,7 +894,13 @@ impl PageServerHandler {
                    "invalid LSN(0) in request".into(),
                ));
            }
-            timeline.wait_lsn(lsn, ctx).await?;
+            timeline
+                .wait_lsn(
+                    lsn,
+                    crate::tenant::timeline::WaitLsnWaiter::PageService,
+                    ctx,
+                )
+                .await?;
        }

        if lsn < **latest_gc_cutoff_lsn {
@@ -1214,7 +1227,13 @@ impl PageServerHandler {
        if let Some(lsn) = lsn {
            // Backup was requested at a particular LSN. Wait for it to arrive.
            info!("waiting for {}", lsn);
-            timeline.wait_lsn(lsn, ctx).await?;
+            timeline
+                .wait_lsn(
+                    lsn,
+                    crate::tenant::timeline::WaitLsnWaiter::PageService,
+                    ctx,
+                )
+                .await?;
            timeline
                .check_lsn_is_in_scope(lsn, &latest_gc_cutoff_lsn)
                .context("invalid basebackup lsn")?;
@@ -34,6 +34,7 @@ use strum::IntoEnumIterator;
 use tokio_util::sync::CancellationToken;
 use tracing::{debug, trace, warn};
 use utils::bin_ser::DeserializeError;
+use utils::vec_map::{VecMap, VecMapOrdering};
 use utils::{bin_ser::BeSer, lsn::Lsn};

 const MAX_AUX_FILE_DELTAS: usize = 1024;
@@ -1546,12 +1547,13 @@ impl<'a> DatadirModification<'a> {
        if !self.pending_updates.is_empty() {
            // The put_batch call below expects expects the inputs to be sorted by Lsn,
            // so we do that first.
-            let lsn_ordered_batch: Vec<(Key, Lsn, Value)> = self
-                .pending_updates
-                .drain()
-                .map(|(key, vals)| vals.into_iter().map(move |(lsn, val)| (key, lsn, val)))
-                .kmerge_by(|lhs, rhs| lhs.1 .0 < rhs.1 .0)
-                .collect();
+            let lsn_ordered_batch: VecMap<Lsn, (Key, Value)> = VecMap::from_iter(
+                self.pending_updates
+                    .drain()
+                    .map(|(key, vals)| vals.into_iter().map(move |(lsn, val)| (lsn, (key, val))))
+                    .kmerge_by(|lhs, rhs| lhs.0 < rhs.0),
+                VecMapOrdering::GreaterOrEqual,
+            );

            writer.put_batch(lsn_ordered_batch, ctx).await?;
        }
@@ -214,13 +214,12 @@ pub enum TaskKind {
    /// Internally, `Client` hands over requests to the `Connection` object.
    /// The `Connection` object is responsible for speaking the wire protocol.
    ///
-    /// Walreceiver uses its own abstraction called `TaskHandle` to represent the activity of establishing and handling a connection.
-    /// That abstraction doesn't use `task_mgr`.
+    /// Walreceiver uses a legacy abstraction called `TaskHandle` to represent the activity of establishing and handling a connection.
    /// The `WalReceiverManager` task ensures that this `TaskHandle` task does not outlive the `WalReceiverManager` task.
    /// For the `RequestContext` that we hand to the TaskHandle, we use the [`WalReceiverConnectionHandler`] task kind.
    ///
-    /// Once the connection is established, the `TaskHandle` task creates a
-    /// [`WalReceiverConnectionPoller`] task_mgr task that is responsible for polling
+    /// Once the connection is established, the `TaskHandle` task spawns a
+    /// [`WalReceiverConnectionPoller`] task that is responsible for polling
    /// the `Connection` object.
    /// A `CancellationToken` created by the `TaskHandle` task ensures
    /// that the [`WalReceiverConnectionPoller`] task will cancel soon after as the `TaskHandle` is dropped.
@@ -230,7 +229,6 @@ pub enum TaskKind {
    WalReceiverManager,

    /// The `TaskHandle` task that executes `handle_walreceiver_connection`.
-    /// Not a `task_mgr` task, but we use this `TaskKind` for its `RequestContext`.
    /// See the comment on [`WalReceiverManager`].
    ///
    /// [`WalReceiverManager`]: Self::WalReceiverManager
@@ -12,6 +12,7 @@
 //!

 use anyhow::{bail, Context};
+use arc_swap::ArcSwap;
 use camino::Utf8Path;
 use camino::Utf8PathBuf;
 use enumset::EnumSet;
@@ -43,6 +44,8 @@ use utils::sync::gate::Gate;
 use utils::sync::gate::GateGuard;
 use utils::timeout::timeout_cancellable;
 use utils::timeout::TimeoutCancellableError;
+use utils::zstd::create_zst_tarball;
+use utils::zstd::extract_zst_tarball;

 use self::config::AttachedLocationConfig;
 use self::config::AttachmentMode;
@@ -96,7 +99,7 @@ use std::ops::Bound::Included;
 use std::sync::atomic::AtomicU64;
 use std::sync::atomic::Ordering;
 use std::sync::Arc;
-use std::sync::{Mutex, RwLock};
+use std::sync::Mutex;
 use std::time::{Duration, Instant};

 use crate::span;
@@ -200,6 +203,13 @@ pub(super) struct AttachedTenantConf {
 }

 impl AttachedTenantConf {
+    fn new(tenant_conf: TenantConfOpt, location: AttachedLocationConfig) -> Self {
+        Self {
+            tenant_conf,
+            location,
+        }
+    }
+
    fn try_from(location_conf: LocationConf) -> anyhow::Result<Self> {
        match &location_conf.mode {
            LocationMode::Attached(attach_conf) => Ok(Self {
@@ -251,7 +261,7 @@ pub struct Tenant {
    // We keep TenantConfOpt sturct here to preserve the information
    // about parameters that are not set.
    // This is necessary to allow global config updates.
-    tenant_conf: Arc<RwLock<AttachedTenantConf>>,
+    tenant_conf: Arc<ArcSwap<AttachedTenantConf>>,

    tenant_shard_id: TenantShardId,

@@ -676,9 +686,20 @@ impl Tenant {
                }

                // Ideally we should use Tenant::set_broken_no_wait, but it is not supposed to be used when tenant is in loading state.
+                enum BrokenVerbosity {
+                    Error,
+                    Info
+                }
                let make_broken =
-                    |t: &Tenant, err: anyhow::Error| {
-                        error!("attach failed, setting tenant state to Broken: {err:?}");
+                    |t: &Tenant, err: anyhow::Error, verbosity: BrokenVerbosity| {
+                        match verbosity {
+                            BrokenVerbosity::Info => {
+                                info!("attach cancelled, setting tenant state to Broken: {err}");
+                            },
+                            BrokenVerbosity::Error => {
+                                error!("attach failed, setting tenant state to Broken: {err:?}");
+                            }
+                        }
                        t.state.send_modify(|state| {
                            // The Stopping case is for when we have passed control on to DeleteTenantFlow:
                            // if it errors, we will call make_broken when tenant is already in Stopping.
@@ -742,7 +763,7 @@ impl Tenant {
                            // Make the tenant broken so that set_stopping will not hang waiting for it to leave
                            // the Attaching state.  This is an over-reaction (nothing really broke, the tenant is
                            // just shutting down), but ensures progress.
-                            make_broken(&tenant_clone, anyhow::anyhow!("Shut down while Attaching"));
+                            make_broken(&tenant_clone, anyhow::anyhow!("Shut down while Attaching"), BrokenVerbosity::Info);
                            return Ok(());
                        },
                    )
@@ -764,7 +785,7 @@ impl Tenant {
                        match res {
                            Ok(p) => Some(p),
                            Err(e) => {
-                                make_broken(&tenant_clone, anyhow::anyhow!(e));
+                                make_broken(&tenant_clone, anyhow::anyhow!(e), BrokenVerbosity::Error);
                                return Ok(());
                            }
                        }
@@ -788,7 +809,7 @@ impl Tenant {
                    {
                        Ok(should_resume_deletion) => should_resume_deletion,
                        Err(err) => {
-                            make_broken(&tenant_clone, anyhow::anyhow!(err));
+                            make_broken(&tenant_clone, anyhow::anyhow!(err), BrokenVerbosity::Error);
                            return Ok(());
                        }
                    }
@@ -818,7 +839,7 @@ impl Tenant {
                    .await;

                    if let Err(e) = deleted {
-                        make_broken(&tenant_clone, anyhow::anyhow!(e));
+                        make_broken(&tenant_clone, anyhow::anyhow!(e), BrokenVerbosity::Error);
                    }

                    return Ok(());
@@ -839,7 +860,7 @@ impl Tenant {
                        tenant_clone.activate(broker_client, None, &ctx);
                    }
                    Err(e) => {
-                        make_broken(&tenant_clone, anyhow::anyhow!(e));
+                        make_broken(&tenant_clone, anyhow::anyhow!(e), BrokenVerbosity::Error);
                    }
                }

@@ -1391,7 +1412,7 @@ impl Tenant {
    /// the same timeline ID already exists, returns CreateTimelineError::AlreadyExists.
    #[allow(clippy::too_many_arguments)]
    pub(crate) async fn create_timeline(
-        &self,
+        self: &Arc<Tenant>,
        new_timeline_id: TimelineId,
        ancestor_timeline_id: Option<TimelineId>,
        mut ancestor_start_lsn: Option<Lsn>,
@@ -1495,7 +1516,7 @@ impl Tenant {
                    // sizes etc. and that would get confused if the previous page versions
                    // are not in the repository yet.
                    ancestor_timeline
-                        .wait_lsn(*lsn, ctx)
+                        .wait_lsn(*lsn, timeline::WaitLsnWaiter::Tenant, ctx)
                        .await
                        .map_err(|e| match e {
                            e @ (WaitLsnError::Timeout(_) | WaitLsnError::BadState) => {
@@ -1539,7 +1560,7 @@ impl Tenant {
            })?;
        }

-        loaded_timeline.activate(broker_client, None, ctx);
+        loaded_timeline.activate(self.clone(), broker_client, None, ctx);

        Ok(loaded_timeline)
    }
@@ -1586,7 +1607,7 @@ impl Tenant {
        );

        {
-            let conf = self.tenant_conf.read().unwrap();
+            let conf = self.tenant_conf.load();

            if !conf.location.may_delete_layers_hint() {
                info!("Skipping GC in location state {:?}", conf.location);
@@ -1613,7 +1634,7 @@ impl Tenant {
        }

        {
-            let conf = self.tenant_conf.read().unwrap();
+            let conf = self.tenant_conf.load();
            if !conf.location.may_delete_layers_hint() || !conf.location.may_upload_layers_hint() {
                info!("Skipping compaction in location state {:?}", conf.location);
                return Ok(());
@@ -1711,7 +1732,12 @@ impl Tenant {
            let mut activated_timelines = 0;

            for timeline in timelines_to_activate {
-                timeline.activate(broker_client.clone(), background_jobs_can_start, ctx);
+                timeline.activate(
+                    self.clone(),
+                    broker_client.clone(),
+                    background_jobs_can_start,
+                    ctx,
+                );
                activated_timelines += 1;
            }

@@ -1757,7 +1783,7 @@ impl Tenant {
    async fn shutdown(
        &self,
        shutdown_progress: completion::Barrier,
-        freeze_and_flush: bool,
+        shutdown_mode: timeline::ShutdownMode,
    ) -> Result<(), completion::Barrier> {
        span::debug_assert_current_span_has_tenant_id();

@@ -1804,16 +1830,8 @@ impl Tenant {
            timelines.values().for_each(|timeline| {
                let timeline = Arc::clone(timeline);
                let timeline_id = timeline.timeline_id;
-
-                let span =
-                    tracing::info_span!("timeline_shutdown", %timeline_id, ?freeze_and_flush);
-                js.spawn(async move {
-                    if freeze_and_flush {
-                        timeline.flush_and_shutdown().instrument(span).await
-                    } else {
-                        timeline.shutdown().instrument(span).await
-                    }
-                });
+                let span = tracing::info_span!("timeline_shutdown", %timeline_id, ?shutdown_mode);
+                js.spawn(async move { timeline.shutdown(shutdown_mode).instrument(span).await });
            })
        };
        // test_long_timeline_create_then_tenant_delete is leaning on this message
@@ -2043,7 +2061,12 @@ impl Tenant {
                TenantState::Active { .. } => {
                    return Ok(());
                }
-                TenantState::Broken { .. } | TenantState::Stopping { .. } => {
+                TenantState::Broken { reason, .. } => {
+                    // This is fatal, and reported distinctly from the general case of "will never be active" because
+                    // it's logically a 500 to external API users (broken is always a bug).
+                    return Err(GetActiveTenantError::Broken(reason));
+                }
+                TenantState::Stopping { .. } => {
                    // There's no chance the tenant can transition back into ::Active
                    return Err(GetActiveTenantError::WillNotBecomeActive(current_state));
                }
@@ -2052,14 +2075,14 @@ impl Tenant {
    }

    pub(crate) fn get_attach_mode(&self) -> AttachmentMode {
-        self.tenant_conf.read().unwrap().location.attach_mode
+        self.tenant_conf.load().location.attach_mode
    }

    /// For API access: generate a LocationConfig equivalent to the one that would be used to
    /// create a Tenant in the same state.  Do not use this in hot paths: it's for relatively
    /// rare external API calls, like a reconciliation at startup.
    pub(crate) fn get_location_conf(&self) -> models::LocationConfig {
-        let conf = self.tenant_conf.read().unwrap();
+        let conf = self.tenant_conf.load();

        let location_config_mode = match conf.location.attach_mode {
            AttachmentMode::Single => models::LocationConfigMode::AttachedSingle,
@@ -2121,7 +2144,7 @@ impl Tenant {

            // Shut down the timeline's remote client: this means that the indices we write
            // for child shards will not be invalidated by the parent shard deleting layers.
-            tl_client.shutdown().await?;
+            tl_client.shutdown().await;

            // Download methods can still be used after shutdown, as they don't flow through the remote client's
            // queue.  In principal the RemoteTimelineClient could provide this without downloading it, but this
@@ -2206,7 +2229,7 @@ where

 impl Tenant {
    pub fn tenant_specific_overrides(&self) -> TenantConfOpt {
-        self.tenant_conf.read().unwrap().tenant_conf.clone()
+        self.tenant_conf.load().tenant_conf.clone()
    }

    pub fn effective_config(&self) -> TenantConf {
@@ -2215,84 +2238,84 @@ impl Tenant {
    }

    pub fn get_checkpoint_distance(&self) -> u64 {
-        let tenant_conf = self.tenant_conf.read().unwrap().tenant_conf.clone();
+        let tenant_conf = self.tenant_conf.load().tenant_conf.clone();
        tenant_conf
            .checkpoint_distance
            .unwrap_or(self.conf.default_tenant_conf.checkpoint_distance)
    }

    pub fn get_checkpoint_timeout(&self) -> Duration {
-        let tenant_conf = self.tenant_conf.read().unwrap().tenant_conf.clone();
+        let tenant_conf = self.tenant_conf.load().tenant_conf.clone();
        tenant_conf
            .checkpoint_timeout
            .unwrap_or(self.conf.default_tenant_conf.checkpoint_timeout)
    }

    pub fn get_compaction_target_size(&self) -> u64 {
-        let tenant_conf = self.tenant_conf.read().unwrap().tenant_conf.clone();
+        let tenant_conf = self.tenant_conf.load().tenant_conf.clone();
        tenant_conf
            .compaction_target_size
            .unwrap_or(self.conf.default_tenant_conf.compaction_target_size)
    }

    pub fn get_compaction_period(&self) -> Duration {
-        let tenant_conf = self.tenant_conf.read().unwrap().tenant_conf.clone();
+        let tenant_conf = self.tenant_conf.load().tenant_conf.clone();
        tenant_conf
            .compaction_period
            .unwrap_or(self.conf.default_tenant_conf.compaction_period)
    }

    pub fn get_compaction_threshold(&self) -> usize {
-        let tenant_conf = self.tenant_conf.read().unwrap().tenant_conf.clone();
+        let tenant_conf = self.tenant_conf.load().tenant_conf.clone();
        tenant_conf
            .compaction_threshold
            .unwrap_or(self.conf.default_tenant_conf.compaction_threshold)
    }

    pub fn get_gc_horizon(&self) -> u64 {
-        let tenant_conf = self.tenant_conf.read().unwrap().tenant_conf.clone();
+        let tenant_conf = self.tenant_conf.load().tenant_conf.clone();
        tenant_conf
            .gc_horizon
            .unwrap_or(self.conf.default_tenant_conf.gc_horizon)
    }

    pub fn get_gc_period(&self) -> Duration {
-        let tenant_conf = self.tenant_conf.read().unwrap().tenant_conf.clone();
+        let tenant_conf = self.tenant_conf.load().tenant_conf.clone();
        tenant_conf
            .gc_period
            .unwrap_or(self.conf.default_tenant_conf.gc_period)
    }

    pub fn get_image_creation_threshold(&self) -> usize {
-        let tenant_conf = self.tenant_conf.read().unwrap().tenant_conf.clone();
+        let tenant_conf = self.tenant_conf.load().tenant_conf.clone();
        tenant_conf
            .image_creation_threshold
            .unwrap_or(self.conf.default_tenant_conf.image_creation_threshold)
    }

    pub fn get_pitr_interval(&self) -> Duration {
-        let tenant_conf = self.tenant_conf.read().unwrap().tenant_conf.clone();
+        let tenant_conf = self.tenant_conf.load().tenant_conf.clone();
        tenant_conf
            .pitr_interval
            .unwrap_or(self.conf.default_tenant_conf.pitr_interval)
    }

    pub fn get_trace_read_requests(&self) -> bool {
-        let tenant_conf = self.tenant_conf.read().unwrap().tenant_conf.clone();
+        let tenant_conf = self.tenant_conf.load().tenant_conf.clone();
        tenant_conf
            .trace_read_requests
            .unwrap_or(self.conf.default_tenant_conf.trace_read_requests)
    }

    pub fn get_min_resident_size_override(&self) -> Option<u64> {
-        let tenant_conf = self.tenant_conf.read().unwrap().tenant_conf.clone();
+        let tenant_conf = self.tenant_conf.load().tenant_conf.clone();
        tenant_conf
            .min_resident_size_override
            .or(self.conf.default_tenant_conf.min_resident_size_override)
    }

    pub fn get_heatmap_period(&self) -> Option<Duration> {
-        let tenant_conf = self.tenant_conf.read().unwrap().tenant_conf.clone();
+        let tenant_conf = self.tenant_conf.load().tenant_conf.clone();
        let heatmap_period = tenant_conf
            .heatmap_period
            .unwrap_or(self.conf.default_tenant_conf.heatmap_period);
@@ -2304,26 +2327,40 @@ impl Tenant {
    }

    pub fn set_new_tenant_config(&self, new_tenant_conf: TenantConfOpt) {
-        self.tenant_conf.write().unwrap().tenant_conf = new_tenant_conf;
-        self.tenant_conf_updated();
+        // Use read-copy-update in order to avoid overwriting the location config
+        // state if this races with [`Tenant::set_new_location_config`]. Note that
+        // this race is not possible if both request types come from the storage
+        // controller (as they should!) because an exclusive op lock is required
+        // on the storage controller side.
+        self.tenant_conf.rcu(|inner| {
+            Arc::new(AttachedTenantConf {
+                tenant_conf: new_tenant_conf.clone(),
+                location: inner.location,
+            })
+        });
+
+        self.tenant_conf_updated(&new_tenant_conf);
        // Don't hold self.timelines.lock() during the notifies.
        // There's no risk of deadlock right now, but there could be if we consolidate
        // mutexes in struct Timeline in the future.
        let timelines = self.list_timelines();
        for timeline in timelines {
-            timeline.tenant_conf_updated();
+            timeline.tenant_conf_updated(&new_tenant_conf);
        }
    }

    pub(crate) fn set_new_location_config(&self, new_conf: AttachedTenantConf) {
-        *self.tenant_conf.write().unwrap() = new_conf;
-        self.tenant_conf_updated();
+        let new_tenant_conf = new_conf.tenant_conf.clone();
+
+        self.tenant_conf.store(Arc::new(new_conf));
+
+        self.tenant_conf_updated(&new_tenant_conf);
        // Don't hold self.timelines.lock() during the notifies.
        // There's no risk of deadlock right now, but there could be if we consolidate
        // mutexes in struct Timeline in the future.
        let timelines = self.list_timelines();
        for timeline in timelines {
-            timeline.tenant_conf_updated();
+            timeline.tenant_conf_updated(&new_tenant_conf);
        }
    }

@@ -2337,11 +2374,8 @@ impl Tenant {
            .unwrap_or(psconf.default_tenant_conf.timeline_get_throttle.clone())
    }

-    pub(crate) fn tenant_conf_updated(&self) {
-        let conf = {
-            let guard = self.tenant_conf.read().unwrap();
-            Self::get_timeline_get_throttle_config(self.conf, &guard.tenant_conf)
-        };
+    pub(crate) fn tenant_conf_updated(&self, new_conf: &TenantConfOpt) {
+        let conf = Self::get_timeline_get_throttle_config(self.conf, new_conf);
        self.timeline_get_throttle.reconfigure(conf)
    }

@@ -2489,7 +2523,7 @@ impl Tenant {
                Tenant::get_timeline_get_throttle_config(conf, &attached_conf.tenant_conf),
                &crate::metrics::tenant_throttling::TIMELINE_GET,
            )),
-            tenant_conf: Arc::new(RwLock::new(attached_conf)),
+            tenant_conf: Arc::new(ArcSwap::from_pointee(attached_conf)),
        }
    }

@@ -3042,8 +3076,13 @@ impl Tenant {
            }
        }

-        let (pgdata_zstd, tar_zst_size) =
-            import_datadir::create_tar_zst(pgdata_path, &temp_path).await?;
+        let (pgdata_zstd, tar_zst_size) = create_zst_tarball(pgdata_path, &temp_path).await?;
+        const INITDB_TAR_ZST_WARN_LIMIT: u64 = 2 * 1024 * 1024;
+        if tar_zst_size > INITDB_TAR_ZST_WARN_LIMIT {
+            warn!(
+                "compressed {temp_path} size of {tar_zst_size} is above limit {INITDB_TAR_ZST_WARN_LIMIT}."
+            );
+        }

        pausable_failpoint!("before-initdb-upload");

@@ -3143,7 +3182,7 @@ impl Tenant {

            let buf_read =
                BufReader::with_capacity(remote_timeline_client::BUFFER_SIZE, initdb_tar_zst);
-            import_datadir::extract_tar_zst(&pgdata_path, buf_read)
+            extract_zst_tarball(&pgdata_path, buf_read)
                .await
                .context("extract initdb tar")?;
        } else {
@@ -3470,7 +3509,7 @@ impl Tenant {
    }

    pub(crate) fn get_tenant_conf(&self) -> TenantConfOpt {
-        self.tenant_conf.read().unwrap().tenant_conf.clone()
+        self.tenant_conf.load().tenant_conf.clone()
    }
 }

@@ -3618,6 +3657,9 @@ pub(crate) mod harness {
                heatmap_period: Some(tenant_conf.heatmap_period),
                lazy_slru_download: Some(tenant_conf.lazy_slru_download),
                timeline_get_throttle: Some(tenant_conf.timeline_get_throttle),
+                image_layer_creation_check_threshold: Some(
+                    tenant_conf.image_layer_creation_check_threshold,
+                ),
            }
        }
    }
@@ -3816,6 +3858,7 @@ mod tests {
    use hex_literal::hex;
    use pageserver_api::keyspace::KeySpace;
    use rand::{thread_rng, Rng};
+    use tests::timeline::ShutdownMode;

    static TEST_KEY: Lazy<Key> =
        Lazy::new(|| Key::from_slice(&hex!("010000000033333333444444445500000001")));
@@ -4261,7 +4304,7 @@ mod tests {
            make_some_layers(tline.as_ref(), Lsn(0x8000), &ctx).await?;
            // so that all uploads finish & we can call harness.load() below again
            tenant
-                .shutdown(Default::default(), true)
+                .shutdown(Default::default(), ShutdownMode::FreezeAndFlush)
                .instrument(harness.span())
                .await
                .ok()
@@ -4302,7 +4345,7 @@ mod tests {

            // so that all uploads finish & we can call harness.load() below again
            tenant
-                .shutdown(Default::default(), true)
+                .shutdown(Default::default(), ShutdownMode::FreezeAndFlush)
                .instrument(harness.span())
                .await
                .ok()
@@ -5083,7 +5126,7 @@ mod tests {
            // Leave the timeline ID in [`Tenant::timelines_creating`] to exclude attempting to create it again
            let raw_tline = tline.raw_timeline().unwrap();
            raw_tline
-                .shutdown()
+                .shutdown(super::timeline::ShutdownMode::Hard)
                .instrument(info_span!("test_shutdown", tenant_id=%raw_tline.tenant_shard_id, shard_id=%raw_tline.tenant_shard_id.shard_slug(), timeline_id=%TIMELINE_ID))
                .await;
            std::mem::forget(tline);
@@ -57,6 +57,9 @@ pub mod defaults {
    // throughputs up to 1GiB/s per timeline.
    pub const DEFAULT_MAX_WALRECEIVER_LSN_WAL_LAG: u64 = 1024 * 1024 * 1024;
    pub const DEFAULT_EVICTIONS_LOW_RESIDENCE_DURATION_METRIC_THRESHOLD: &str = "24 hour";
+    // By default ingest enough WAL for two new L0 layers before checking if new image
+    // image layers should be created.
+    pub const DEFAULT_IMAGE_LAYER_CREATION_CHECK_THRESHOLD: u8 = 2;

    pub const DEFAULT_INGEST_BATCH_SIZE: u64 = 100;
 }
@@ -196,16 +199,17 @@ impl LocationConf {
    /// For use when attaching/re-attaching: update the generation stored in this
    /// structure.  If we were in a secondary state, promote to attached (posession
    /// of a fresh generation implies this).
-    pub(crate) fn attach_in_generation(&mut self, generation: Generation) {
+    pub(crate) fn attach_in_generation(&mut self, mode: AttachmentMode, generation: Generation) {
        match &mut self.mode {
            LocationMode::Attached(attach_conf) => {
                attach_conf.generation = generation;
+                attach_conf.attach_mode = mode;
            }
            LocationMode::Secondary(_) => {
                // We are promoted to attached by the control plane's re-attach response
                self.mode = LocationMode::Attached(AttachedLocationConfig {
                    generation,
-                    attach_mode: AttachmentMode::Single,
+                    attach_mode: mode,
                })
            }
        }
@@ -361,6 +365,10 @@ pub struct TenantConf {
    pub lazy_slru_download: bool,

    pub timeline_get_throttle: pageserver_api::models::ThrottleConfig,
+
+    // How much WAL must be ingested before checking again whether a new image layer is required.
+    // Expresed in multiples of checkpoint distance.
+    pub image_layer_creation_check_threshold: u8,
 }

 /// Same as TenantConf, but this struct preserves the information about
@@ -453,6 +461,9 @@ pub struct TenantConfOpt {

    #[serde(skip_serializing_if = "Option::is_none")]
    pub timeline_get_throttle: Option<pageserver_api::models::ThrottleConfig>,
+
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub image_layer_creation_check_threshold: Option<u8>,
 }

 impl TenantConfOpt {
@@ -507,6 +518,9 @@ impl TenantConfOpt {
                .timeline_get_throttle
                .clone()
                .unwrap_or(global_conf.timeline_get_throttle),
+            image_layer_creation_check_threshold: self
+                .image_layer_creation_check_threshold
+                .unwrap_or(global_conf.image_layer_creation_check_threshold),
        }
    }
 }
@@ -547,6 +561,7 @@ impl Default for TenantConf {
            heatmap_period: Duration::ZERO,
            lazy_slru_download: false,
            timeline_get_throttle: crate::tenant::throttle::Config::disabled(),
+            image_layer_creation_check_threshold: DEFAULT_IMAGE_LAYER_CREATION_CHECK_THRESHOLD,
        }
    }
 }
@@ -620,6 +635,7 @@ impl From<TenantConfOpt> for models::TenantConfig {
            heatmap_period: value.heatmap_period.map(humantime),
            lazy_slru_download: value.lazy_slru_download,
            timeline_get_throttle: value.timeline_get_throttle.map(ThrottleConfig::from),
+            image_layer_creation_check_threshold: value.image_layer_creation_check_threshold,
        }
    }
 }
@@ -14,7 +14,10 @@ use crate::{
    config::PageServerConf,
    context::RequestContext,
    task_mgr::{self, TaskKind},
-    tenant::mgr::{TenantSlot, TenantsMapRemoveResult},
+    tenant::{
+        mgr::{TenantSlot, TenantsMapRemoveResult},
+        timeline::ShutdownMode,
+    },
 };

 use super::{
@@ -111,6 +114,7 @@ async fn create_local_delete_mark(
    let _ = std::fs::OpenOptions::new()
        .write(true)
        .create(true)
+        .truncate(true)
        .open(&marker_path)
        .with_context(|| format!("could not create delete marker file {marker_path:?}"))?;

@@ -462,7 +466,7 @@ impl DeleteTenantFlow {
        // tenant.shutdown
        // Its also bad that we're holding tenants.read here.
        // TODO relax set_stopping to be idempotent?
-        if tenant.shutdown(progress, false).await.is_err() {
+        if tenant.shutdown(progress, ShutdownMode::Hard).await.is_err() {
            return Err(DeleteTenantError::Other(anyhow::anyhow!(
                "tenant shutdown is already in progress"
            )));
@@ -72,6 +72,10 @@ impl EphemeralFile {
        self.len
    }

+    pub(crate) fn id(&self) -> page_cache::FileId {
+        self.page_cache_file_id
+    }
+
    pub(crate) async fn read_blk(
        &self,
        blknum: u32,
@@ -346,35 +346,6 @@ where
    }
 }

-#[derive(PartialEq, Eq, Hash, Debug, Clone)]
-pub enum InMemoryLayerHandle {
-    Open {
-        lsn_floor: Lsn,
-        end_lsn: Lsn,
-    },
-    Frozen {
-        idx: usize,
-        lsn_floor: Lsn,
-        end_lsn: Lsn,
-    },
-}
-
-impl InMemoryLayerHandle {
-    pub fn get_lsn_floor(&self) -> Lsn {
-        match self {
-            InMemoryLayerHandle::Open { lsn_floor, .. } => *lsn_floor,
-            InMemoryLayerHandle::Frozen { lsn_floor, .. } => *lsn_floor,
-        }
-    }
-
-    pub fn get_end_lsn(&self) -> Lsn {
-        match self {
-            InMemoryLayerHandle::Open { end_lsn, .. } => *end_lsn,
-            InMemoryLayerHandle::Frozen { end_lsn, .. } => *end_lsn,
-        }
-    }
-}
-
 impl LayerMap {
    ///
    /// Find the latest layer (by lsn.end) that covers the given
@@ -576,41 +547,18 @@ impl LayerMap {
        self.historic.iter()
    }

-    /// Get a handle for the first in memory layer that matches the provided predicate.
-    /// The handle should be used with [`Self::get_in_memory_layer`] to retrieve the actual layer.
-    ///
-    /// Note: [`Self::find_in_memory_layer`] and [`Self::get_in_memory_layer`] should be called during
-    /// the same exclusive region established by holding the layer manager lock.
-    pub fn find_in_memory_layer<Pred>(&self, mut pred: Pred) -> Option<InMemoryLayerHandle>
+    /// Get a ref counted pointer for the first in memory layer that matches the provided predicate.
+    pub fn find_in_memory_layer<Pred>(&self, mut pred: Pred) -> Option<Arc<InMemoryLayer>>
    where
        Pred: FnMut(&Arc<InMemoryLayer>) -> bool,
    {
        if let Some(open) = &self.open_layer {
            if pred(open) {
-                return Some(InMemoryLayerHandle::Open {
-                    lsn_floor: open.get_lsn_range().start,
-                    end_lsn: open.get_lsn_range().end,
-                });
+                return Some(open.clone());
            }
        }

-        let pos = self.frozen_layers.iter().rev().position(pred);
-        pos.map(|rev_idx| {
-            let idx = self.frozen_layers.len() - 1 - rev_idx;
-            InMemoryLayerHandle::Frozen {
-                idx,
-                lsn_floor: self.frozen_layers[idx].get_lsn_range().start,
-                end_lsn: self.frozen_layers[idx].get_lsn_range().end,
-            }
-        })
-    }
-
-    /// Get the layer pointed to by the provided handle.
-    pub fn get_in_memory_layer(&self, handle: &InMemoryLayerHandle) -> Option<Arc<InMemoryLayer>> {
-        match handle {
-            InMemoryLayerHandle::Open { .. } => self.open_layer.clone(),
-            InMemoryLayerHandle::Frozen { idx, .. } => self.frozen_layers.get(*idx).cloned(),
-        }
+        self.frozen_layers.iter().rfind(|l| pred(l)).cloned()
    }

    ///
@@ -2,13 +2,13 @@
 //! page server.

 use camino::{Utf8DirEntry, Utf8Path, Utf8PathBuf};
-use futures::stream::StreamExt;
 use itertools::Itertools;
 use pageserver_api::key::Key;
-use pageserver_api::models::ShardParameters;
+use pageserver_api::models::LocationConfigMode;
 use pageserver_api::shard::{
    ShardCount, ShardIdentity, ShardNumber, ShardStripeSize, TenantShardId,
 };
+use pageserver_api::upcall_api::ReAttachResponseTenant;
 use rand::{distributions::Alphanumeric, Rng};
 use std::borrow::Cow;
 use std::cmp::Ordering;
@@ -16,6 +16,7 @@ use std::collections::{BTreeMap, HashMap};
 use std::ops::Deref;
 use std::sync::Arc;
 use std::time::{Duration, Instant};
+use sysinfo::SystemExt;
 use tokio::fs;
 use utils::timeout::{timeout_cancellable, TimeoutCancellableError};

@@ -39,10 +40,11 @@ use crate::metrics::{TENANT, TENANT_MANAGER as METRICS};
 use crate::task_mgr::{self, TaskKind};
 use crate::tenant::config::{
    AttachedLocationConfig, AttachmentMode, LocationConf, LocationMode, SecondaryLocationConfig,
-    TenantConfOpt,
 };
 use crate::tenant::delete::DeleteTenantFlow;
 use crate::tenant::span::debug_assert_current_span_has_tenant_id;
+use crate::tenant::storage_layer::inmemory_layer;
+use crate::tenant::timeline::ShutdownMode;
 use crate::tenant::{AttachedTenantConf, SpawnMode, Tenant, TenantState};
 use crate::{InitializationOrder, IGNORED_TENANT_FILE_NAME, METADATA_FILE_NAME, TEMP_FILE_SUFFIX};

@@ -125,6 +127,46 @@ pub(crate) enum ShardSelector {
    Page(Key),
 }

+/// A convenience for use with the re_attach ControlPlaneClient function: rather
+/// than the serializable struct, we build this enum that encapsulates
+/// the invariant that attached tenants always have generations.
+///
+/// This represents the subset of a LocationConfig that we receive during re-attach.
+pub(crate) enum TenantStartupMode {
+    Attached((AttachmentMode, Generation)),
+    Secondary,
+}
+
+impl TenantStartupMode {
+    /// Return the generation & mode that should be used when starting
+    /// this tenant.
+    ///
+    /// If this returns None, the re-attach struct is in an invalid state and
+    /// should be ignored in the response.
+    fn from_reattach_tenant(rart: ReAttachResponseTenant) -> Option<Self> {
+        match (rart.mode, rart.gen) {
+            (LocationConfigMode::Detached, _) => None,
+            (LocationConfigMode::Secondary, _) => Some(Self::Secondary),
+            (LocationConfigMode::AttachedMulti, Some(g)) => {
+                Some(Self::Attached((AttachmentMode::Multi, Generation::new(g))))
+            }
+            (LocationConfigMode::AttachedSingle, Some(g)) => {
+                Some(Self::Attached((AttachmentMode::Single, Generation::new(g))))
+            }
+            (LocationConfigMode::AttachedStale, Some(g)) => {
+                Some(Self::Attached((AttachmentMode::Stale, Generation::new(g))))
+            }
+            _ => {
+                tracing::warn!(
+                    "Received invalid re-attach state for tenant {}: {rart:?}",
+                    rart.id
+                );
+                None
+            }
+        }
+    }
+}
+
 impl TenantsMap {
    /// Convenience function for typical usage, where we want to get a `Tenant` object, for
    /// working with attached tenants.  If the TenantId is in the map but in Secondary state,
@@ -271,7 +313,7 @@ pub struct TenantManager {

 fn emergency_generations(
    tenant_confs: &HashMap<TenantShardId, anyhow::Result<LocationConf>>,
-) -> HashMap<TenantShardId, Generation> {
+) -> HashMap<TenantShardId, TenantStartupMode> {
    tenant_confs
        .iter()
        .filter_map(|(tid, lc)| {
@@ -279,12 +321,15 @@ fn emergency_generations(
                Ok(lc) => lc,
                Err(_) => return None,
            };
-            let gen = match &lc.mode {
-                LocationMode::Attached(alc) => Some(alc.generation),
-                LocationMode::Secondary(_) => None,
-            };
-
-            gen.map(|g| (*tid, g))
+            Some((
+                *tid,
+                match &lc.mode {
+                    LocationMode::Attached(alc) => {
+                        TenantStartupMode::Attached((alc.attach_mode, alc.generation))
+                    }
+                    LocationMode::Secondary(_) => TenantStartupMode::Secondary,
+                },
+            ))
        })
        .collect()
 }
@@ -294,7 +339,7 @@ async fn init_load_generations(
    tenant_confs: &HashMap<TenantShardId, anyhow::Result<LocationConf>>,
    resources: &TenantSharedResources,
    cancel: &CancellationToken,
-) -> anyhow::Result<Option<HashMap<TenantShardId, Generation>>> {
+) -> anyhow::Result<Option<HashMap<TenantShardId, TenantStartupMode>>> {
    let generations = if conf.control_plane_emergency_mode {
        error!(
            "Emergency mode!  Tenants will be attached unsafely using their last known generation"
@@ -304,7 +349,12 @@ async fn init_load_generations(
        info!("Calling control plane API to re-attach tenants");
        // If we are configured to use the control plane API, then it is the source of truth for what tenants to load.
        match client.re_attach(conf).await {
-            Ok(tenants) => tenants,
+            Ok(tenants) => tenants
+                .into_iter()
+                .flat_map(|(id, rart)| {
+                    TenantStartupMode::from_reattach_tenant(rart).map(|tsm| (id, tsm))
+                })
+                .collect(),
            Err(RetryForeverError::ShuttingDown) => {
                anyhow::bail!("Shut down while waiting for control plane re-attach response")
            }
@@ -322,9 +372,17 @@ async fn init_load_generations(
    // Must only do this if remote storage is enabled, otherwise deletion queue
    // is not running and channel push will fail.
    if resources.remote_storage.is_some() {
-        resources
-            .deletion_queue_client
-            .recover(generations.clone())?;
+        let attached_tenants = generations
+            .iter()
+            .flat_map(|(id, start_mode)| {
+                match start_mode {
+                    TenantStartupMode::Attached((_mode, generation)) => Some(generation),
+                    TenantStartupMode::Secondary => None,
+                }
+                .map(|gen| (*id, *gen))
+            })
+            .collect();
+        resources.deletion_queue_client.recover(attached_tenants)?;
    }

    Ok(Some(generations))
@@ -487,12 +545,23 @@ pub async fn init_tenant_mgr(

    let ctx = RequestContext::todo_child(TaskKind::Startup, DownloadBehavior::Warn);

+    // Initialize dynamic limits that depend on system resources
+    let system_memory =
+        sysinfo::System::new_with_specifics(sysinfo::RefreshKind::new().with_memory())
+            .total_memory();
+    let max_ephemeral_layer_bytes =
+        conf.ephemeral_bytes_per_memory_kb as u64 * (system_memory / 1024);
+    tracing::info!("Initialized ephemeral layer size limit to {max_ephemeral_layer_bytes}, for {system_memory} bytes of memory");
+    inmemory_layer::GLOBAL_RESOURCES.max_dirty_bytes.store(
+        max_ephemeral_layer_bytes,
+        std::sync::atomic::Ordering::Relaxed,
+    );
+
    // Scan local filesystem for attached tenants
    let tenant_configs = init_load_tenant_configs(conf).await?;

-    // Determine which tenants are to be attached
-    let tenant_generations =
-        init_load_generations(conf, &tenant_configs, &resources, &cancel).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?;

    tracing::info!(
        "Attaching {} tenants at startup, warming up {} at a time",
@@ -522,97 +591,102 @@ pub async fn init_tenant_mgr(
            }
        };

-        let generation = if let Some(generations) = &tenant_generations {
+        // FIXME: if we were attached, and get demoted to secondary on re-attach, we
+        // don't have a place to get a config.
+        // (https://github.com/neondatabase/neon/issues/5377)
+        const DEFAULT_SECONDARY_CONF: SecondaryLocationConfig =
+            SecondaryLocationConfig { warm: true };
+
+        // Update the location config according to the re-attach response
+        if let Some(tenant_modes) = &tenant_modes {
            // We have a generation map: treat it as the authority for whether
            // this tenant is really attached.
-            if let Some(gen) = generations.get(&tenant_shard_id) {
-                if let LocationMode::Attached(attached) = &location_conf.mode {
-                    if attached.generation > *gen {
+            match tenant_modes.get(&tenant_shard_id) {
+                None => {
+                    info!(tenant_id=%tenant_shard_id.tenant_id, shard_id=%tenant_shard_id.shard_slug(), "Detaching tenant, control plane omitted it in re-attach response");
+                    if let Err(e) = safe_remove_tenant_dir_all(&tenant_dir_path).await {
+                        error!(tenant_id=%tenant_shard_id.tenant_id, shard_id=%tenant_shard_id.shard_slug(),
+                            "Failed to remove detached tenant directory '{tenant_dir_path}': {e:?}",
+                        );
+                    }
+
+                    // We deleted local content: move on to next tenant, don't try and spawn this one.
+                    continue;
+                }
+                Some(TenantStartupMode::Secondary) => {
+                    if !matches!(location_conf.mode, LocationMode::Secondary(_)) {
+                        location_conf.mode = LocationMode::Secondary(DEFAULT_SECONDARY_CONF);
+                    }
+                }
+                Some(TenantStartupMode::Attached((attach_mode, generation))) => {
+                    let old_gen_higher = match &location_conf.mode {
+                        LocationMode::Attached(AttachedLocationConfig {
+                            generation: old_generation,
+                            attach_mode: _attach_mode,
+                        }) => {
+                            if old_generation > generation {
+                                Some(old_generation)
+                            } else {
+                                None
+                            }
+                        }
+                        _ => None,
+                    };
+                    if let Some(old_generation) = old_gen_higher {
                        tracing::error!(tenant_id=%tenant_shard_id.tenant_id, shard_id=%tenant_shard_id.shard_slug(),
-                            "Control plane gave decreasing generation ({gen:?}) in re-attach response for tenant that was attached in generation {:?}, demoting to secondary",
-                            attached.generation
+                            "Control plane gave decreasing generation ({generation:?}) in re-attach response for tenant that was attached in generation {:?}, demoting to secondary",
+                            old_generation
                        );

                        // We cannot safely attach this tenant given a bogus generation number, but let's avoid throwing away
                        // local disk content: demote to secondary rather than detaching.
-                        tenants.insert(
-                            tenant_shard_id,
-                            TenantSlot::Secondary(SecondaryTenant::new(
-                                tenant_shard_id,
-                                location_conf.shard,
-                                location_conf.tenant_conf.clone(),
-                                &SecondaryLocationConfig { warm: false },
-                            )),
-                        );
+                        location_conf.mode = LocationMode::Secondary(DEFAULT_SECONDARY_CONF);
+                    } else {
+                        location_conf.attach_in_generation(*attach_mode, *generation);
                    }
                }
-                *gen
-            } else {
-                match &location_conf.mode {
-                    LocationMode::Secondary(secondary_config) => {
-                        // We do not require the control plane's permission for secondary mode
-                        // tenants, because they do no remote writes and hence require no
-                        // generation number
-                        info!(tenant_id=%tenant_shard_id.tenant_id, shard_id=%tenant_shard_id.shard_slug(), "Loaded tenant in secondary mode");
-                        tenants.insert(
-                            tenant_shard_id,
-                            TenantSlot::Secondary(SecondaryTenant::new(
-                                tenant_shard_id,
-                                location_conf.shard,
-                                location_conf.tenant_conf,
-                                secondary_config,
-                            )),
-                        );
-                    }
-                    LocationMode::Attached(_) => {
-                        // TODO: augment re-attach API to enable the control plane to
-                        // instruct us about secondary attachments.  That way, instead of throwing
-                        // away local state, we can gracefully fall back to secondary here, if the control
-                        // plane tells us so.
-                        // (https://github.com/neondatabase/neon/issues/5377)
-                        info!(tenant_id=%tenant_shard_id.tenant_id, shard_id=%tenant_shard_id.shard_slug(), "Detaching tenant, control plane omitted it in re-attach response");
-                        if let Err(e) = safe_remove_tenant_dir_all(&tenant_dir_path).await {
-                            error!(tenant_id=%tenant_shard_id.tenant_id, shard_id=%tenant_shard_id.shard_slug(),
-                                "Failed to remove detached tenant directory '{tenant_dir_path}': {e:?}",
-                            );
-                        }
-                    }
-                };
-
-                continue;
            }
        } else {
            // Legacy mode: no generation information, any tenant present
            // on local disk may activate
            info!(tenant_id=%tenant_shard_id.tenant_id, shard_id=%tenant_shard_id.shard_slug(), "Starting tenant in legacy mode, no generation",);
-            Generation::none()
        };

        // Presence of a generation number implies attachment: attach the tenant
        // if it wasn't already, and apply the generation number.
-        location_conf.attach_in_generation(generation);
        Tenant::persist_tenant_config(conf, &tenant_shard_id, &location_conf).await?;

        let shard_identity = location_conf.shard;
-        match tenant_spawn(
-            conf,
-            tenant_shard_id,
-            &tenant_dir_path,
-            resources.clone(),
-            AttachedTenantConf::try_from(location_conf)?,
-            shard_identity,
-            Some(init_order.clone()),
-            &TENANTS,
-            SpawnMode::Lazy,
-            &ctx,
-        ) {
-            Ok(tenant) => {
-                tenants.insert(tenant_shard_id, TenantSlot::Attached(tenant));
+        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;
+                    }
+                }
            }
-            Err(e) => {
-                error!(tenant_id=%tenant_shard_id.tenant_id, shard_id=%tenant_shard_id.shard_slug(), "Failed to start tenant: {e:#}");
-            }
-        }
+            LocationMode::Secondary(secondary_conf) => TenantSlot::Secondary(SecondaryTenant::new(
+                tenant_shard_id,
+                shard_identity,
+                location_conf.tenant_conf,
+                &secondary_conf,
+            )),
+        };
+
+        tenants.insert(tenant_shard_id, slot);
    }

    info!("Processed {} local tenants at startup", tenants.len());
@@ -710,11 +784,9 @@ async fn shutdown_all_tenants0(tenants: &std::sync::RwLock<TenantsMap>) {
                            shutdown_state.insert(tenant_shard_id, TenantSlot::Attached(t.clone()));
                            join_set.spawn(
                                async move {
-                                    let freeze_and_flush = true;
-
                                    let res = {
                                        let (_guard, shutdown_progress) = completion::channel();
-                                        t.shutdown(shutdown_progress, freeze_and_flush).await
+                                        t.shutdown(shutdown_progress, ShutdownMode::FreezeAndFlush).await
                                    };

                                    if let Err(other_progress) = res {
@@ -815,16 +887,6 @@ async fn shutdown_all_tenants0(tenants: &std::sync::RwLock<TenantsMap>) {
    // caller will log how long we took
 }

-#[derive(Debug, thiserror::Error)]
-pub(crate) enum SetNewTenantConfigError {
-    #[error(transparent)]
-    GetTenant(#[from] GetTenantError),
-    #[error(transparent)]
-    Persist(anyhow::Error),
-    #[error(transparent)]
-    Other(anyhow::Error),
-}
-
 #[derive(thiserror::Error, Debug)]
 pub(crate) enum UpsertLocationError {
    #[error("Bad config request: {0}")]
@@ -850,32 +912,21 @@ impl TenantManager {
        self.conf
    }

-    /// Gets the attached tenant from the in-memory data, erroring if it's absent, in secondary mode, or is not fitting to the query.
-    /// `active_only = true` allows to query only tenants that are ready for operations, erroring on other kinds of tenants.
+    /// Gets the attached tenant from the in-memory data, erroring if it's absent, in secondary mode, or currently
+    /// undergoing a state change (i.e. slot is InProgress).
+    ///
+    /// The return Tenant is not guaranteed to be active: check its status after obtaing it, or
+    /// use [`Tenant::wait_to_become_active`] before using it if you will do I/O on it.
    pub(crate) fn get_attached_tenant_shard(
        &self,
        tenant_shard_id: TenantShardId,
-        active_only: bool,
    ) -> Result<Arc<Tenant>, GetTenantError> {
        let locked = self.tenants.read().unwrap();

        let peek_slot = tenant_map_peek_slot(&locked, &tenant_shard_id, TenantSlotPeekMode::Read)?;

        match peek_slot {
-            Some(TenantSlot::Attached(tenant)) => match tenant.current_state() {
-                TenantState::Broken {
-                    reason,
-                    backtrace: _,
-                } if active_only => Err(GetTenantError::Broken(reason)),
-                TenantState::Active => Ok(Arc::clone(tenant)),
-                _ => {
-                    if active_only {
-                        Err(GetTenantError::NotActive(tenant_shard_id))
-                    } else {
-                        Ok(Arc::clone(tenant))
-                    }
-                }
-            },
+            Some(TenantSlot::Attached(tenant)) => Ok(Arc::clone(tenant)),
            Some(TenantSlot::InProgress(_)) => Err(GetTenantError::NotActive(tenant_shard_id)),
            None | Some(TenantSlot::Secondary(_)) => {
                Err(GetTenantError::NotFound(tenant_shard_id.tenant_id))
@@ -1055,7 +1106,7 @@ impl TenantManager {
                };

                info!("Shutting down attached tenant");
-                match tenant.shutdown(progress, false).await {
+                match tenant.shutdown(progress, ShutdownMode::Hard).await {
                    Ok(()) => {}
                    Err(barrier) => {
                        info!("Shutdown already in progress, waiting for it to complete");
@@ -1171,7 +1222,7 @@ impl TenantManager {
                    TenantSlot::Attached(tenant) => {
                        let (_guard, progress) = utils::completion::channel();
                        info!("Shutting down just-spawned tenant, because tenant manager is shut down");
-                        match tenant.shutdown(progress, false).await {
+                        match tenant.shutdown(progress, ShutdownMode::Hard).await {
                            Ok(()) => {
                                info!("Finished shutting down just-spawned tenant");
                            }
@@ -1221,7 +1272,7 @@ impl TenantManager {
        };

        let (_guard, progress) = utils::completion::channel();
-        match tenant.shutdown(progress, false).await {
+        match tenant.shutdown(progress, ShutdownMode::Hard).await {
            Ok(()) => {
                slot_guard.drop_old_value()?;
            }
@@ -1368,7 +1419,8 @@ impl TenantManager {
                    .wait_to_become_active(activation_timeout)
                    .await
                    .map_err(|e| match e {
-                        GetActiveTenantError::WillNotBecomeActive(_) => {
+                        GetActiveTenantError::WillNotBecomeActive(_)
+                        | GetActiveTenantError::Broken(_) => {
                            DeleteTenantError::InvalidState(tenant.current_state())
                        }
                        GetActiveTenantError::Cancelled => DeleteTenantError::Cancelled,
@@ -1395,29 +1447,30 @@ impl TenantManager {
        result
    }

-    #[instrument(skip_all, fields(tenant_id=%tenant_shard_id.tenant_id, shard_id=%tenant_shard_id.shard_slug(), new_shard_count=%new_shard_count.literal()))]
+    #[instrument(skip_all, fields(tenant_id=%tenant.get_tenant_shard_id().tenant_id, shard_id=%tenant.get_tenant_shard_id().shard_slug(), new_shard_count=%new_shard_count.literal()))]
    pub(crate) async fn shard_split(
        &self,
-        tenant_shard_id: TenantShardId,
+        tenant: Arc<Tenant>,
        new_shard_count: ShardCount,
        new_stripe_size: Option<ShardStripeSize>,
        ctx: &RequestContext,
    ) -> anyhow::Result<Vec<TenantShardId>> {
+        let tenant_shard_id = *tenant.get_tenant_shard_id();
        let r = self
-            .do_shard_split(tenant_shard_id, new_shard_count, new_stripe_size, ctx)
+            .do_shard_split(tenant, new_shard_count, new_stripe_size, ctx)
            .await;
        if r.is_err() {
            // Shard splitting might have left the original shard in a partially shut down state (it
            // stops the shard's remote timeline client).  Reset it to ensure we leave things in
            // a working state.
            if self.get(tenant_shard_id).is_some() {
-                tracing::warn!("Resetting {tenant_shard_id} after shard split failure");
+                tracing::warn!("Resetting after shard split failure");
                if let Err(e) = self.reset_tenant(tenant_shard_id, false, ctx).await {
                    // Log this error because our return value will still be the original error, not this one.  This is
                    // a severe error: if this happens, we might be leaving behind a tenant that is not fully functional
                    // (e.g. has uploads disabled).  We can't do anything else: if reset fails then shutting the tenant down or
                    // setting it broken probably won't help either.
-                    tracing::error!("Failed to reset {tenant_shard_id}: {e}");
+                    tracing::error!("Failed to reset: {e}");
                }
            }
        }
@@ -1427,12 +1480,12 @@ impl TenantManager {

    pub(crate) async fn do_shard_split(
        &self,
-        tenant_shard_id: TenantShardId,
+        tenant: Arc<Tenant>,
        new_shard_count: ShardCount,
        new_stripe_size: Option<ShardStripeSize>,
        ctx: &RequestContext,
    ) -> anyhow::Result<Vec<TenantShardId>> {
-        let tenant = get_tenant(tenant_shard_id, true)?;
+        let tenant_shard_id = *tenant.get_tenant_shard_id();

        // Validate the incoming request
        if new_shard_count.count() <= tenant_shard_id.shard_count.count() {
@@ -1478,7 +1531,6 @@ impl TenantManager {
            // If [`Tenant::split_prepare`] fails, we must reload the tenant, because it might
            // have been left in a partially-shut-down state.
            tracing::warn!("Failed to prepare for split: {e}, reloading Tenant before returning");
-            self.reset_tenant(tenant_shard_id, false, ctx).await?;
            return Err(e);
        }

@@ -1596,7 +1648,14 @@ impl TenantManager {
                    fail::fail_point!("shard-split-lsn-wait", |_| Err(anyhow::anyhow!(
                        "failpoint"
                    )));
-                    if let Err(e) = timeline.wait_lsn(*target_lsn, ctx).await {
+                    if let Err(e) = timeline
+                        .wait_lsn(
+                            *target_lsn,
+                            crate::tenant::timeline::WaitLsnWaiter::Tenant,
+                            ctx,
+                        )
+                        .await
+                    {
                        // Failure here might mean shutdown, in any case this part is an optimization
                        // and we shouldn't hold up the split operation.
                        tracing::warn!(
@@ -1617,7 +1676,7 @@ impl TenantManager {

        // Phase 5: Shut down the parent shard, and erase it from disk
        let (_guard, progress) = completion::channel();
-        match parent.shutdown(progress, false).await {
+        match parent.shutdown(progress, ShutdownMode::Hard).await {
            Ok(()) => {}
            Err(other) => {
                other.wait().await;
@@ -1662,9 +1721,9 @@ impl TenantManager {
                    .layers
                    .read()
                    .await
-                    .resident_layers()
-                    .collect::<Vec<_>>()
-                    .await;
+                    .likely_resident_layers()
+                    .collect::<Vec<_>>();
+
                for layer in timeline_layers {
                    let relative_path = layer
                        .local_path()
@@ -1876,38 +1935,23 @@ impl TenantManager {
        removal_result
    }

-    pub(crate) async fn set_new_tenant_config(
+    pub(crate) fn list_tenants(
        &self,
-        new_tenant_conf: TenantConfOpt,
-        tenant_id: TenantId,
-    ) -> Result<(), SetNewTenantConfigError> {
-        // Legacy API: does not support sharding
-        let tenant_shard_id = TenantShardId::unsharded(tenant_id);
-
-        info!("configuring tenant {tenant_id}");
-        let tenant = get_tenant(tenant_shard_id, true)?;
-
-        if !tenant.tenant_shard_id().shard_count.is_unsharded() {
-            // Note that we use ShardParameters::default below.
-            return Err(SetNewTenantConfigError::Other(anyhow::anyhow!(
-            "This API may only be used on single-sharded tenants, use the /location_config API for sharded tenants"
-        )));
-        }
-
-        // This is a legacy API that only operates on attached tenants: the preferred
-        // API to use is the location_config/ endpoint, which lets the caller provide
-        // the full LocationConf.
-        let location_conf = LocationConf::attached_single(
-            new_tenant_conf.clone(),
-            tenant.generation,
-            &ShardParameters::default(),
-        );
-
-        Tenant::persist_tenant_config(self.conf, &tenant_shard_id, &location_conf)
-            .await
-            .map_err(SetNewTenantConfigError::Persist)?;
-        tenant.set_new_tenant_config(new_tenant_conf);
-        Ok(())
+    ) -> Result<Vec<(TenantShardId, TenantState, Generation)>, TenantMapListError> {
+        let tenants = TENANTS.read().unwrap();
+        let m = match &*tenants {
+            TenantsMap::Initializing => return Err(TenantMapListError::Initializing),
+            TenantsMap::Open(m) | TenantsMap::ShuttingDown(m) => m,
+        };
+        Ok(m.iter()
+            .filter_map(|(id, tenant)| match tenant {
+                TenantSlot::Attached(tenant) => {
+                    Some((*id, tenant.current_state(), tenant.generation()))
+                }
+                TenantSlot::Secondary(_) => None,
+                TenantSlot::InProgress(_) => None,
+            })
+            .collect())
    }
 }

@@ -1920,51 +1964,12 @@ pub(crate) enum GetTenantError {

    #[error("Tenant {0} is not active")]
    NotActive(TenantShardId),
-    /// Broken is logically a subset of NotActive, but a distinct error is useful as
-    /// NotActive is usually a retryable state for API purposes, whereas Broken
-    /// is a stuck error state
-    #[error("Tenant is broken: {0}")]
-    Broken(String),

    // Initializing or shutting down: cannot authoritatively say whether we have this tenant
    #[error("Tenant map is not available: {0}")]
    MapState(#[from] TenantMapError),
 }

-/// Gets the tenant from the in-memory data, erroring if it's absent or is not fitting to the query.
-/// `active_only = true` allows to query only tenants that are ready for operations, erroring on other kinds of tenants.
-///
-/// This method is cancel-safe.
-pub(crate) fn get_tenant(
-    tenant_shard_id: TenantShardId,
-    active_only: bool,
-) -> Result<Arc<Tenant>, GetTenantError> {
-    let locked = TENANTS.read().unwrap();
-
-    let peek_slot = tenant_map_peek_slot(&locked, &tenant_shard_id, TenantSlotPeekMode::Read)?;
-
-    match peek_slot {
-        Some(TenantSlot::Attached(tenant)) => match tenant.current_state() {
-            TenantState::Broken {
-                reason,
-                backtrace: _,
-            } if active_only => Err(GetTenantError::Broken(reason)),
-            TenantState::Active => Ok(Arc::clone(tenant)),
-            _ => {
-                if active_only {
-                    Err(GetTenantError::NotActive(tenant_shard_id))
-                } else {
-                    Ok(Arc::clone(tenant))
-                }
-            }
-        },
-        Some(TenantSlot::InProgress(_)) => Err(GetTenantError::NotActive(tenant_shard_id)),
-        None | Some(TenantSlot::Secondary(_)) => {
-            Err(GetTenantError::NotFound(tenant_shard_id.tenant_id))
-        }
-    }
-}
-
 #[derive(thiserror::Error, Debug)]
 pub(crate) enum GetActiveTenantError {
    /// We may time out either while TenantSlot is InProgress, or while the Tenant
@@ -1988,6 +1993,12 @@ pub(crate) enum GetActiveTenantError {
    /// Tenant exists, but is in a state that cannot become active (e.g. Stopping, Broken)
    #[error("will not become active.  Current state: {0}")]
    WillNotBecomeActive(TenantState),
+
+    /// Broken is logically a subset of WillNotBecomeActive, but a distinct error is useful as
+    /// WillNotBecomeActive is a permitted error under some circumstances, whereas broken should
+    /// never happen.
+    #[error("Tenant is broken: {0}")]
+    Broken(String),
 }

 /// Get a [`Tenant`] in its active state. If the tenant_id is currently in [`TenantSlot::InProgress`]
@@ -2143,7 +2154,7 @@ pub(crate) async fn load_tenant(

    let mut location_conf =
        Tenant::load_tenant_config(conf, &tenant_shard_id).map_err(TenantMapInsertError::Other)?;
-    location_conf.attach_in_generation(generation);
+    location_conf.attach_in_generation(AttachmentMode::Single, generation);

    Tenant::persist_tenant_config(conf, &tenant_shard_id, &location_conf).await?;

@@ -2207,27 +2218,6 @@ pub(crate) enum TenantMapListError {
    Initializing,
 }

-///
-/// Get list of tenants, for the mgmt API
-///
-pub(crate) async fn list_tenants(
-) -> Result<Vec<(TenantShardId, TenantState, Generation)>, TenantMapListError> {
-    let tenants = TENANTS.read().unwrap();
-    let m = match &*tenants {
-        TenantsMap::Initializing => return Err(TenantMapListError::Initializing),
-        TenantsMap::Open(m) | TenantsMap::ShuttingDown(m) => m,
-    };
-    Ok(m.iter()
-        .filter_map(|(id, tenant)| match tenant {
-            TenantSlot::Attached(tenant) => {
-                Some((*id, tenant.current_state(), tenant.generation()))
-            }
-            TenantSlot::Secondary(_) => None,
-            TenantSlot::InProgress(_) => None,
-        })
-        .collect())
-}
-
 #[derive(Debug, thiserror::Error)]
 pub(crate) enum TenantMapInsertError {
    #[error(transparent)]
@@ -2673,11 +2663,11 @@ where
    let attached_tenant = match slot_guard.get_old_value() {
        Some(TenantSlot::Attached(tenant)) => {
            // whenever we remove a tenant from memory, we don't want to flush and wait for upload
-            let freeze_and_flush = false;
+            let shutdown_mode = ShutdownMode::Hard;

            // shutdown is sure to transition tenant to stopping, and wait for all tasks to complete, so
            // that we can continue safely to cleanup.
-            match tenant.shutdown(progress, freeze_and_flush).await {
+            match tenant.shutdown(progress, shutdown_mode).await {
                Ok(()) => {}
                Err(_other) => {
                    // if pageserver shutdown or other detach/ignore is already ongoing, we don't want to
@@ -200,6 +200,7 @@ use utils::backoff::{
 use std::collections::{HashMap, VecDeque};
 use std::sync::atomic::{AtomicU32, Ordering};
 use std::sync::{Arc, Mutex};
+use std::time::Duration;

 use remote_storage::{DownloadError, GenericRemoteStorage, RemotePath, TimeoutOrCancel};
 use std::ops::DerefMut;
@@ -207,7 +208,7 @@ use tracing::{debug, error, info, instrument, warn};
 use tracing::{info_span, Instrument};
 use utils::lsn::Lsn;

-use crate::deletion_queue::DeletionQueueClient;
+use crate::deletion_queue::{DeletionQueueClient, DeletionQueueError};
 use crate::metrics::{
    MeasureRemoteOp, RemoteOpFileKind, RemoteOpKind, RemoteTimelineClientMetrics,
    RemoteTimelineClientMetricsCallTrackSize, REMOTE_ONDEMAND_DOWNLOADED_BYTES,
@@ -217,7 +218,7 @@ use crate::task_mgr::shutdown_token;
 use crate::tenant::debug_assert_current_span_has_tenant_and_timeline_id;
 use crate::tenant::remote_timeline_client::download::download_retry;
 use crate::tenant::storage_layer::AsLayerDesc;
-use crate::tenant::upload_queue::Delete;
+use crate::tenant::upload_queue::{Delete, UploadQueueStoppedDeletable};
 use crate::tenant::TIMELINES_SEGMENT_NAME;
 use crate::{
    config::PageServerConf,
@@ -261,20 +262,15 @@ pub(crate) const INITDB_PRESERVED_PATH: &str = "initdb-preserved.tar.zst";
 /// Default buffer size when interfacing with [`tokio::fs::File`].
 pub(crate) const BUFFER_SIZE: usize = 32 * 1024;

+/// Doing non-essential flushes of deletion queue is subject to this timeout, after
+/// which we warn and skip.
+const DELETION_QUEUE_FLUSH_TIMEOUT: Duration = Duration::from_secs(10);
+
 pub enum MaybeDeletedIndexPart {
    IndexPart(IndexPart),
    Deleted(IndexPart),
 }

-/// Errors that can arise when calling [`RemoteTimelineClient::stop`].
-#[derive(Debug, thiserror::Error)]
-pub enum StopError {
-    /// Returned if the upload queue was never initialized.
-    /// See [`RemoteTimelineClient::init_upload_queue`] and [`RemoteTimelineClient::init_upload_queue_for_empty_remote`].
-    #[error("queue is not initialized")]
-    QueueUninitialized,
-}
-
 #[derive(Debug, thiserror::Error)]
 pub enum PersistIndexPartWithDeletedFlagError {
    #[error("another task is already setting the deleted_flag, started at {0:?}")]
@@ -399,15 +395,10 @@ impl RemoteTimelineClient {
            "bug: it is responsibility of the caller to provide index part from MaybeDeletedIndexPart::Deleted"
        ))?;

-        {
-            let mut upload_queue = self.upload_queue.lock().unwrap();
-            upload_queue.initialize_with_current_remote_index_part(index_part)?;
-            self.update_remote_physical_size_gauge(Some(index_part));
-        }
-        // also locks upload queue, without dropping the guard above it will be a deadlock
-        self.stop().expect("initialized line above");
-
        let mut upload_queue = self.upload_queue.lock().unwrap();
+        upload_queue.initialize_with_current_remote_index_part(index_part)?;
+        self.update_remote_physical_size_gauge(Some(index_part));
+        self.stop_impl(&mut upload_queue);

        upload_queue
            .stopped_mut()
@@ -421,7 +412,8 @@ impl RemoteTimelineClient {
        match &mut *self.upload_queue.lock().unwrap() {
            UploadQueue::Uninitialized => None,
            UploadQueue::Initialized(q) => q.get_last_remote_consistent_lsn_projected(),
-            UploadQueue::Stopped(q) => q
+            UploadQueue::Stopped(UploadQueueStopped::Uninitialized) => None,
+            UploadQueue::Stopped(UploadQueueStopped::Deletable(q)) => q
                .upload_queue_for_deletion
                .get_last_remote_consistent_lsn_projected(),
        }
@@ -431,7 +423,8 @@ impl RemoteTimelineClient {
        match &mut *self.upload_queue.lock().unwrap() {
            UploadQueue::Uninitialized => None,
            UploadQueue::Initialized(q) => Some(q.get_last_remote_consistent_lsn_visible()),
-            UploadQueue::Stopped(q) => Some(
+            UploadQueue::Stopped(UploadQueueStopped::Uninitialized) => None,
+            UploadQueue::Stopped(UploadQueueStopped::Deletable(q)) => Some(
                q.upload_queue_for_deletion
                    .get_last_remote_consistent_lsn_visible(),
            ),
@@ -600,14 +593,14 @@ impl RemoteTimelineClient {
        upload_queue: &mut UploadQueueInitialized,
        metadata: TimelineMetadata,
    ) {
+        let disk_consistent_lsn = upload_queue.latest_metadata.disk_consistent_lsn();
+
        info!(
-            "scheduling metadata upload with {} files ({} changed)",
+            "scheduling metadata upload up to consistent LSN {disk_consistent_lsn} with {} files ({} changed)",
            upload_queue.latest_files.len(),
            upload_queue.latest_files_changes_since_metadata_upload_scheduled,
        );

-        let disk_consistent_lsn = upload_queue.latest_metadata.disk_consistent_lsn();
-
        let index_part = IndexPart::new(
            upload_queue.latest_files.clone(),
            disk_consistent_lsn,
@@ -898,7 +891,7 @@ impl RemoteTimelineClient {
    /// Wait for all previously scheduled operations to complete, and then stop.
    ///
    /// Not cancellation safe
-    pub(crate) async fn shutdown(self: &Arc<Self>) -> Result<(), StopError> {
+    pub(crate) async fn shutdown(self: &Arc<Self>) {
        // On cancellation the queue is left in ackward state of refusing new operations but
        // proper stop is yet to be called. On cancel the original or some later task must call
        // `stop` or `shutdown`.
@@ -909,8 +902,12 @@ impl RemoteTimelineClient {
        let fut = {
            let mut guard = self.upload_queue.lock().unwrap();
            let upload_queue = match &mut *guard {
-                UploadQueue::Stopped(_) => return Ok(()),
-                UploadQueue::Uninitialized => return Err(StopError::QueueUninitialized),
+                UploadQueue::Stopped(_) => return,
+                UploadQueue::Uninitialized => {
+                    // transition into Stopped state
+                    self.stop_impl(&mut guard);
+                    return;
+                }
                UploadQueue::Initialized(ref mut init) => init,
            };

@@ -942,7 +939,7 @@ impl RemoteTimelineClient {
            }
        }

-        self.stop()
+        self.stop();
    }

    /// Set the deleted_at field in the remote index file.
@@ -1058,6 +1055,26 @@ impl RemoteTimelineClient {
        Ok(())
    }

+    async fn flush_deletion_queue(&self) -> Result<(), DeletionQueueError> {
+        match tokio::time::timeout(
+            DELETION_QUEUE_FLUSH_TIMEOUT,
+            self.deletion_queue_client.flush_immediate(),
+        )
+        .await
+        {
+            Ok(result) => result,
+            Err(_timeout) => {
+                // Flushing remote deletions is not mandatory: we flush here to make the system easier to test, and
+                // to ensure that _usually_ objects are really gone after a DELETE is acked.  However, in case of deletion
+                // queue issues (https://github.com/neondatabase/neon/issues/6440), we don't want to wait indefinitely here.
+                tracing::warn!(
+                    "Timed out waiting for deletion queue flush, acking deletion anyway"
+                );
+                Ok(())
+            }
+        }
+    }
+
    /// Prerequisites: UploadQueue should be in stopped state and deleted_at should be successfuly set.
    /// The function deletes layer files one by one, then lists the prefix to see if we leaked something
    /// deletes leaked files if any and proceeds with deletion of index file at the end.
@@ -1107,7 +1124,7 @@ impl RemoteTimelineClient {

        // Execute all pending deletions, so that when we proceed to do a list_prefixes below, we aren't
        // taking the burden of listing all the layers that we already know we should delete.
-        self.deletion_queue_client.flush_immediate().await?;
+        self.flush_deletion_queue().await?;

        let cancel = shutdown_token();

@@ -1181,7 +1198,7 @@ impl RemoteTimelineClient {

        // Timeline deletion is rare and we have probably emitted a reasonably number of objects: wait
        // for a flush to a persistent deletion list so that we may be sure deletion will occur.
-        self.deletion_queue_client.flush_immediate().await?;
+        self.flush_deletion_queue().await?;

        fail::fail_point!("timeline-delete-after-index-delete", |_| {
            Err(anyhow::anyhow!(
@@ -1324,12 +1341,7 @@ impl RemoteTimelineClient {
            // upload finishes or times out soon enough.
            if cancel.is_cancelled() {
                info!("upload task cancelled by shutdown request");
-                match self.stop() {
-                    Ok(()) => {}
-                    Err(StopError::QueueUninitialized) => {
-                        unreachable!("we never launch an upload task if the queue is uninitialized, and once it is initialized, we never go back")
-                    }
-                }
+                self.stop();
                return;
            }

@@ -1582,19 +1594,25 @@ impl RemoteTimelineClient {
    /// Use [`RemoteTimelineClient::shutdown`] for graceful stop.
    ///
    /// In-progress operations will still be running after this function returns.
-    /// Use `task_mgr::shutdown_tasks(None, Some(self.tenant_id), Some(timeline_id))`
+    /// Use `task_mgr::shutdown_tasks(Some(TaskKind::RemoteUploadTask), Some(self.tenant_shard_id), Some(timeline_id))`
    /// to wait for them to complete, after calling this function.
-    pub(crate) fn stop(&self) -> Result<(), StopError> {
+    pub(crate) fn stop(&self) {
        // Whichever *task* for this RemoteTimelineClient grabs the mutex first will transition the queue
        // into stopped state, thereby dropping all off the queued *ops* which haven't become *tasks* yet.
        // The other *tasks* will come here and observe an already shut down queue and hence simply wrap up their business.
        let mut guard = self.upload_queue.lock().unwrap();
-        match &mut *guard {
-            UploadQueue::Uninitialized => Err(StopError::QueueUninitialized),
+        self.stop_impl(&mut guard);
+    }
+
+    fn stop_impl(&self, guard: &mut std::sync::MutexGuard<UploadQueue>) {
+        match &mut **guard {
+            UploadQueue::Uninitialized => {
+                info!("UploadQueue is in state Uninitialized, nothing to do");
+                **guard = UploadQueue::Stopped(UploadQueueStopped::Uninitialized);
+            }
            UploadQueue::Stopped(_) => {
                // nothing to do
                info!("another concurrent task already shut down the queue");
-                Ok(())
            }
            UploadQueue::Initialized(initialized) => {
                info!("shutting down upload queue");
@@ -1627,11 +1645,13 @@ impl RemoteTimelineClient {
                    };

                    let upload_queue = std::mem::replace(
-                        &mut *guard,
-                        UploadQueue::Stopped(UploadQueueStopped {
-                            upload_queue_for_deletion,
-                            deleted_at: SetDeletedFlagProgress::NotRunning,
-                        }),
+                        &mut **guard,
+                        UploadQueue::Stopped(UploadQueueStopped::Deletable(
+                            UploadQueueStoppedDeletable {
+                                upload_queue_for_deletion,
+                                deleted_at: SetDeletedFlagProgress::NotRunning,
+                            },
+                        )),
                    );
                    if let UploadQueue::Initialized(qi) = upload_queue {
                        qi
@@ -1660,10 +1680,6 @@ impl RemoteTimelineClient {
                    // which is exactly what we want to happen.
                    drop(op);
                }
-
-                // We're done.
-                drop(guard);
-                Ok(())
            }
        }
    }
@@ -15,6 +15,7 @@ use crate::{
    tenant::{
        config::SecondaryLocationConfig,
        debug_assert_current_span_has_tenant_and_timeline_id,
+        ephemeral_file::is_ephemeral_file,
        remote_timeline_client::{
            index::LayerFileMetadata, is_temp_download_file, FAILED_DOWNLOAD_WARN_THRESHOLD,
            FAILED_REMOTE_OP_RETRIES,
@@ -534,7 +535,11 @@ impl<'a> TenantDownloader<'a> {
            .await
            .maybe_fatal_err(&context_msg)?;

-        tracing::debug!("Wrote local heatmap to {}", heatmap_path);
+        tracing::debug!(
+            "Wrote local heatmap to {}, with {} timelines",
+            heatmap_path,
+            heatmap.timelines.len()
+        );

        // Clean up any local layers that aren't in the heatmap.  We do this first for all timelines, on the general
        // principle that deletions should be done before writes wherever possible, and so that we can use this
@@ -547,6 +552,10 @@ impl<'a> TenantDownloader<'a> {
        // Download the layers in the heatmap
        for timeline in heatmap.timelines {
            if self.secondary_state.cancel.is_cancelled() {
+                tracing::debug!(
+                    "Cancelled before downloading timeline {}",
+                    timeline.timeline_id
+                );
                return Ok(());
            }

@@ -764,16 +773,48 @@ impl<'a> TenantDownloader<'a> {
            }
        };

+        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 Ok(());
            }

            // Existing on-disk layers: just update their access time.
            if let Some(on_disk) = timeline_state.on_disk_layers.get(&layer.name) {
                tracing::debug!("Layer {} is already on disk", layer.name);
+
+                if cfg!(debug_assertions) {
+                    // Debug for https://github.com/neondatabase/neon/issues/6966: check that the files we think
+                    // are already present on disk are really there.
+                    let local_path = self
+                        .conf
+                        .timeline_path(tenant_shard_id, &timeline.timeline_id)
+                        .join(layer.name.file_name());
+                    match tokio::fs::metadata(&local_path).await {
+                        Ok(meta) => {
+                            tracing::debug!(
+                                "Layer {} present at {}, size {}",
+                                layer.name,
+                                local_path,
+                                meta.len(),
+                            );
+                        }
+                        Err(e) => {
+                            tracing::warn!(
+                                "Layer {} not found at {} ({})",
+                                layer.name,
+                                local_path,
+                                e
+                            );
+                            debug_assert!(false);
+                        }
+                    }
+                }
+
                if on_disk.metadata != LayerFileMetadata::from(&layer.metadata)
                    || on_disk.access_time != layer.access_time
                {
@@ -950,7 +991,10 @@ async fn init_timeline_state(
            // Secondary mode doesn't use local metadata files, but they might have been left behind by an attached tenant.
            warn!(path=?dentry.path(), "found legacy metadata file, these should have been removed in load_tenant_config");
            continue;
-        } else if crate::is_temporary(&file_path) || is_temp_download_file(&file_path) {
+        } else if crate::is_temporary(&file_path)
+            || is_temp_download_file(&file_path)
+            || is_ephemeral_file(file_name)
+        {
            // Temporary files are frequently left behind from restarting during downloads
            tracing::info!("Cleaning up temporary file {file_path}");
            if let Err(e) = tokio::fs::remove_file(&file_path)
@@ -9,6 +9,7 @@ use crate::{
    metrics::SECONDARY_MODE,
    tenant::{
        config::AttachmentMode,
+        mgr::GetTenantError,
        mgr::TenantManager,
        remote_timeline_client::remote_heatmap_path,
        span::debug_assert_current_span_has_tenant_id,
@@ -292,8 +293,11 @@ impl JobGenerator<UploadPending, WriteInProgress, WriteComplete, UploadCommand>
            "Starting heatmap write on command");
        let tenant = self
            .tenant_manager
-            .get_attached_tenant_shard(*tenant_shard_id, true)
+            .get_attached_tenant_shard(*tenant_shard_id)
            .map_err(|e| anyhow::anyhow!(e))?;
+        if !tenant.is_active() {
+            return Err(GetTenantError::NotActive(*tenant_shard_id).into());
+        }

        Ok(UploadPending {
            // Ignore our state for last digest: this forces an upload even if nothing has changed
@@ -300,6 +300,7 @@ where

        let tenant_shard_id = job.get_tenant_shard_id();
        let barrier = if let Some(barrier) = self.get_running(tenant_shard_id) {
+            tracing::info!("Command already running, waiting for it");
            barrier
        } else {
            let running = self.spawn_now(job);
@@ -3,7 +3,7 @@
 pub mod delta_layer;
 mod filename;
 pub mod image_layer;
-mod inmemory_layer;
+pub(crate) mod inmemory_layer;
 pub(crate) mod layer;
 mod layer_desc;

@@ -25,7 +25,7 @@ use std::cmp::{Ordering, Reverse};
 use std::collections::hash_map::Entry;
 use std::collections::{BinaryHeap, HashMap};
 use std::ops::Range;
-use std::sync::Mutex;
+use std::sync::{Arc, Mutex};
 use std::time::{Duration, SystemTime, UNIX_EPOCH};
 use tracing::warn;
 use utils::history_buffer::HistoryBufferWithDropCounter;
@@ -41,8 +41,8 @@ pub use layer_desc::{PersistentLayerDesc, PersistentLayerKey};

 pub(crate) use layer::{EvictionError, Layer, ResidentLayer};

-use super::layer_map::InMemoryLayerHandle;
-use super::timeline::layer_manager::LayerManager;
+use self::inmemory_layer::InMemoryLayerFileId;
+
 use super::timeline::GetVectoredError;
 use super::PageReconstructError;

@@ -204,23 +204,30 @@ impl Default for ValuesReconstructState {
    }
 }

-/// Description of layer to be read - the layer map can turn
-/// this description into the actual layer.
-#[derive(PartialEq, Eq, Hash, Debug, Clone)]
-pub(crate) enum ReadableLayerDesc {
-    Persistent {
-        desc: PersistentLayerDesc,
-        lsn_range: Range<Lsn>,
-    },
-    InMemory {
-        handle: InMemoryLayerHandle,
-        lsn_ceil: Lsn,
-    },
+/// A key that uniquely identifies a layer in a timeline
+#[derive(Debug, PartialEq, Eq, Clone, Hash)]
+pub(crate) enum LayerId {
+    PersitentLayerId(PersistentLayerKey),
+    InMemoryLayerId(InMemoryLayerFileId),
 }

-/// Wraper for 'ReadableLayerDesc' sorted by Lsn
+/// Layer wrapper for the read path. Note that it is valid
+/// to use these layers even after external operations have
+/// been performed on them (compaction, freeze, etc.).
 #[derive(Debug)]
-struct ReadableLayerDescOrdered(ReadableLayerDesc);
+pub(crate) enum ReadableLayer {
+    PersistentLayer(Layer),
+    InMemoryLayer(Arc<InMemoryLayer>),
+}
+
+/// A partial description of a read to be done.
+#[derive(Debug, Clone)]
+struct ReadDesc {
+    /// An id used to resolve the readable layer within the fringe
+    layer_id: LayerId,
+    /// Lsn range for the read, used for selecting the next read
+    lsn_range: Range<Lsn>,
+}

 /// Data structure which maintains a fringe of layers for the
 /// read path. The fringe is the set of layers which intersects
@@ -231,41 +238,64 @@ struct ReadableLayerDescOrdered(ReadableLayerDesc);
 /// a two layer indexing scheme.
 #[derive(Debug)]
 pub(crate) struct LayerFringe {
-    layers_by_lsn: BinaryHeap<ReadableLayerDescOrdered>,
-    layers: HashMap<ReadableLayerDesc, KeySpace>,
+    planned_reads_by_lsn: BinaryHeap<ReadDesc>,
+    layers: HashMap<LayerId, LayerKeyspace>,
+}
+
+#[derive(Debug)]
+struct LayerKeyspace {
+    layer: ReadableLayer,
+    target_keyspace: KeySpace,
 }

 impl LayerFringe {
    pub(crate) fn new() -> Self {
        LayerFringe {
-            layers_by_lsn: BinaryHeap::new(),
+            planned_reads_by_lsn: BinaryHeap::new(),
            layers: HashMap::new(),
        }
    }

-    pub(crate) fn next_layer(&mut self) -> Option<(ReadableLayerDesc, KeySpace)> {
-        let handle = match self.layers_by_lsn.pop() {
-            Some(h) => h,
+    pub(crate) fn next_layer(&mut self) -> Option<(ReadableLayer, KeySpace, Range<Lsn>)> {
+        let read_desc = match self.planned_reads_by_lsn.pop() {
+            Some(desc) => desc,
            None => return None,
        };

-        let removed = self.layers.remove_entry(&handle.0);
+        let removed = self.layers.remove_entry(&read_desc.layer_id);
        match removed {
-            Some((layer, keyspace)) => Some((layer, keyspace)),
+            Some((
+                _,
+                LayerKeyspace {
+                    layer,
+                    target_keyspace,
+                },
+            )) => Some((layer, target_keyspace, read_desc.lsn_range)),
            None => unreachable!("fringe internals are always consistent"),
        }
    }

-    pub(crate) fn update(&mut self, layer: ReadableLayerDesc, keyspace: KeySpace) {
-        let entry = self.layers.entry(layer.clone());
+    pub(crate) fn update(
+        &mut self,
+        layer: ReadableLayer,
+        keyspace: KeySpace,
+        lsn_range: Range<Lsn>,
+    ) {
+        let layer_id = layer.id();
+        let entry = self.layers.entry(layer_id.clone());
        match entry {
            Entry::Occupied(mut entry) => {
-                entry.get_mut().merge(&keyspace);
+                entry.get_mut().target_keyspace.merge(&keyspace);
            }
            Entry::Vacant(entry) => {
-                self.layers_by_lsn
-                    .push(ReadableLayerDescOrdered(entry.key().clone()));
-                entry.insert(keyspace);
+                self.planned_reads_by_lsn.push(ReadDesc {
+                    lsn_range,
+                    layer_id: layer_id.clone(),
+                });
+                entry.insert(LayerKeyspace {
+                    layer,
+                    target_keyspace: keyspace,
+                });
            }
        }
    }
@@ -277,77 +307,55 @@ impl Default for LayerFringe {
    }
 }

-impl Ord for ReadableLayerDescOrdered {
+impl Ord for ReadDesc {
    fn cmp(&self, other: &Self) -> Ordering {
-        let ord = self.0.get_lsn_ceil().cmp(&other.0.get_lsn_ceil());
+        let ord = self.lsn_range.end.cmp(&other.lsn_range.end);
        if ord == std::cmp::Ordering::Equal {
-            self.0
-                .get_lsn_floor()
-                .cmp(&other.0.get_lsn_floor())
-                .reverse()
+            self.lsn_range.start.cmp(&other.lsn_range.start).reverse()
        } else {
            ord
        }
    }
 }

-impl PartialOrd for ReadableLayerDescOrdered {
+impl PartialOrd for ReadDesc {
    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
        Some(self.cmp(other))
    }
 }

-impl PartialEq for ReadableLayerDescOrdered {
+impl PartialEq for ReadDesc {
    fn eq(&self, other: &Self) -> bool {
-        self.0.get_lsn_floor() == other.0.get_lsn_floor()
-            && self.0.get_lsn_ceil() == other.0.get_lsn_ceil()
+        self.lsn_range == other.lsn_range
    }
 }

-impl Eq for ReadableLayerDescOrdered {}
+impl Eq for ReadDesc {}

-impl ReadableLayerDesc {
-    pub(crate) fn get_lsn_floor(&self) -> Lsn {
+impl ReadableLayer {
+    pub(crate) fn id(&self) -> LayerId {
        match self {
-            ReadableLayerDesc::Persistent { lsn_range, .. } => lsn_range.start,
-            ReadableLayerDesc::InMemory { handle, .. } => handle.get_lsn_floor(),
-        }
-    }
-
-    pub(crate) fn get_lsn_ceil(&self) -> Lsn {
-        match self {
-            ReadableLayerDesc::Persistent { lsn_range, .. } => lsn_range.end,
-            ReadableLayerDesc::InMemory { lsn_ceil, .. } => *lsn_ceil,
+            Self::PersistentLayer(layer) => LayerId::PersitentLayerId(layer.layer_desc().key()),
+            Self::InMemoryLayer(layer) => LayerId::InMemoryLayerId(layer.file_id()),
        }
    }

    pub(crate) async fn get_values_reconstruct_data(
        &self,
-        layer_manager: &LayerManager,
        keyspace: KeySpace,
+        lsn_range: Range<Lsn>,
        reconstruct_state: &mut ValuesReconstructState,
        ctx: &RequestContext,
    ) -> Result<(), GetVectoredError> {
        match self {
-            ReadableLayerDesc::Persistent { desc, lsn_range } => {
-                let layer = layer_manager.get_from_desc(desc);
+            ReadableLayer::PersistentLayer(layer) => {
                layer
-                    .get_values_reconstruct_data(
-                        keyspace,
-                        lsn_range.clone(),
-                        reconstruct_state,
-                        ctx,
-                    )
+                    .get_values_reconstruct_data(keyspace, lsn_range, reconstruct_state, ctx)
                    .await
            }
-            ReadableLayerDesc::InMemory { handle, lsn_ceil } => {
-                let layer = layer_manager
-                    .layer_map()
-                    .get_in_memory_layer(handle)
-                    .unwrap();
-
+            ReadableLayer::InMemoryLayer(layer) => {
                layer
-                    .get_values_reconstruct_data(keyspace, *lsn_ceil, reconstruct_state, ctx)
+                    .get_values_reconstruct_data(keyspace, lsn_range.end, reconstruct_state, ctx)
                    .await
            }
        }
@@ -47,6 +47,7 @@ use anyhow::{anyhow, bail, ensure, Context, Result};
 use bytes::BytesMut;
 use camino::{Utf8Path, Utf8PathBuf};
 use futures::StreamExt;
+use itertools::Itertools;
 use pageserver_api::keyspace::KeySpace;
 use pageserver_api::models::LayerAccessKind;
 use pageserver_api::shard::TenantShardId;
@@ -946,6 +947,34 @@ impl DeltaLayerInner {
        Ok(planner.finish())
    }

+    fn get_min_read_buffer_size(
+        planned_reads: &[VectoredRead],
+        read_size_soft_max: usize,
+    ) -> usize {
+        let Some(largest_read) = planned_reads.iter().max_by_key(|read| read.size()) else {
+            return read_size_soft_max;
+        };
+
+        let largest_read_size = largest_read.size();
+        if largest_read_size > read_size_soft_max {
+            // If the read is oversized, it should only contain one key.
+            let offenders = largest_read
+                .blobs_at
+                .as_slice()
+                .iter()
+                .map(|(_, blob_meta)| format!("{}@{}", blob_meta.key, blob_meta.lsn))
+                .join(", ");
+            tracing::warn!(
+                "Oversized vectored read ({} > {}) for keys {}",
+                largest_read_size,
+                read_size_soft_max,
+                offenders
+            );
+        }
+
+        largest_read_size
+    }
+
    async fn do_reads_and_update_state(
        &self,
        reads: Vec<VectoredRead>,
@@ -959,7 +988,8 @@ impl DeltaLayerInner {
            .expect("Layer is loaded with max vectored bytes config")
            .0
            .into();
-        let mut buf = Some(BytesMut::with_capacity(max_vectored_read_bytes));
+        let buf_size = Self::get_min_read_buffer_size(&reads, max_vectored_read_bytes);
+        let mut buf = Some(BytesMut::with_capacity(buf_size));

        // Note that reads are processed in reverse order (from highest key+lsn).
        // This is the order that `ReconstructState` requires such that it can
@@ -986,7 +1016,7 @@ impl DeltaLayerInner {

                    // We have "lost" the buffer since the lower level IO api
                    // doesn't return the buffer on error. Allocate a new one.
-                    buf = Some(BytesMut::with_capacity(max_vectored_read_bytes));
+                    buf = Some(BytesMut::with_capacity(buf_size));

                    continue;
                }
@@ -1210,9 +1240,16 @@ impl<'a> pageserver_compaction::interface::CompactionDeltaEntry<'a, Key> for Del
 mod test {
    use std::collections::BTreeMap;

+    use itertools::MinMaxResult;
+    use rand::prelude::{SeedableRng, SliceRandom, StdRng};
+    use rand::RngCore;
+
    use super::*;
    use crate::{
-        context::DownloadBehavior, task_mgr::TaskKind, tenant::disk_btree::tests::TestDisk,
+        context::DownloadBehavior,
+        task_mgr::TaskKind,
+        tenant::{disk_btree::tests::TestDisk, harness::TenantHarness},
+        DEFAULT_PG_VERSION,
    };

    /// Construct an index for a fictional delta layer and and then
@@ -1332,4 +1369,229 @@ mod test {

        assert_eq!(planned_blobs, expected_blobs);
    }
+
+    mod constants {
+        use utils::lsn::Lsn;
+
+        /// Offset used by all lsns in this test
+        pub(super) const LSN_OFFSET: Lsn = Lsn(0x08);
+        /// Number of unique keys including in the test data
+        pub(super) const KEY_COUNT: u8 = 60;
+        /// Max number of different lsns for each key
+        pub(super) const MAX_ENTRIES_PER_KEY: u8 = 20;
+        /// Possible value sizes for each key along with a probability weight
+        pub(super) const VALUE_SIZES: [(usize, u8); 3] = [(100, 2), (1024, 2), (1024 * 1024, 1)];
+        /// Probability that there will be a gap between the current key and the next one (33.3%)
+        pub(super) const KEY_GAP_CHANGES: [(bool, u8); 2] = [(true, 1), (false, 2)];
+        /// The minimum size of a key range in all the generated reads
+        pub(super) const MIN_RANGE_SIZE: i128 = 10;
+        /// The number of ranges included in each vectored read
+        pub(super) const RANGES_COUNT: u8 = 2;
+        /// The number of vectored reads performed
+        pub(super) const READS_COUNT: u8 = 100;
+        /// Soft max size of a vectored read. Will be violated if we have to read keys
+        /// with values larger than the limit
+        pub(super) const MAX_VECTORED_READ_BYTES: usize = 64 * 1024;
+    }
+
+    struct Entry {
+        key: Key,
+        lsn: Lsn,
+        value: Vec<u8>,
+    }
+
+    fn generate_entries(rng: &mut StdRng) -> Vec<Entry> {
+        let mut current_key = Key::MIN;
+
+        let mut entries = Vec::new();
+        for _ in 0..constants::KEY_COUNT {
+            let count = rng.gen_range(1..constants::MAX_ENTRIES_PER_KEY);
+            let mut lsns_iter =
+                std::iter::successors(Some(Lsn(constants::LSN_OFFSET.0 + 0x08)), |lsn| {
+                    Some(Lsn(lsn.0 + 0x08))
+                });
+            let mut lsns = Vec::new();
+            while lsns.len() < count as usize {
+                let take = rng.gen_bool(0.5);
+                let lsn = lsns_iter.next().unwrap();
+                if take {
+                    lsns.push(lsn);
+                }
+            }
+
+            for lsn in lsns {
+                let size = constants::VALUE_SIZES
+                    .choose_weighted(rng, |item| item.1)
+                    .unwrap()
+                    .0;
+                let mut buf = vec![0; size];
+                rng.fill_bytes(&mut buf);
+
+                entries.push(Entry {
+                    key: current_key,
+                    lsn,
+                    value: buf,
+                })
+            }
+
+            let gap = constants::KEY_GAP_CHANGES
+                .choose_weighted(rng, |item| item.1)
+                .unwrap()
+                .0;
+            if gap {
+                current_key = current_key.add(2);
+            } else {
+                current_key = current_key.add(1);
+            }
+        }
+
+        entries
+    }
+
+    struct EntriesMeta {
+        key_range: Range<Key>,
+        lsn_range: Range<Lsn>,
+        index: BTreeMap<(Key, Lsn), Vec<u8>>,
+    }
+
+    fn get_entries_meta(entries: &[Entry]) -> EntriesMeta {
+        let key_range = match entries.iter().minmax_by_key(|e| e.key) {
+            MinMaxResult::MinMax(min, max) => min.key..max.key.next(),
+            _ => panic!("More than one entry is always expected"),
+        };
+
+        let lsn_range = match entries.iter().minmax_by_key(|e| e.lsn) {
+            MinMaxResult::MinMax(min, max) => min.lsn..Lsn(max.lsn.0 + 1),
+            _ => panic!("More than one entry is always expected"),
+        };
+
+        let mut index = BTreeMap::new();
+        for entry in entries.iter() {
+            index.insert((entry.key, entry.lsn), entry.value.clone());
+        }
+
+        EntriesMeta {
+            key_range,
+            lsn_range,
+            index,
+        }
+    }
+
+    fn pick_random_keyspace(rng: &mut StdRng, key_range: &Range<Key>) -> KeySpace {
+        let start = key_range.start.to_i128();
+        let end = key_range.end.to_i128();
+
+        let mut keyspace = KeySpace::default();
+
+        for _ in 0..constants::RANGES_COUNT {
+            let mut range: Option<Range<Key>> = Option::default();
+            while range.is_none() || keyspace.overlaps(range.as_ref().unwrap()) {
+                let range_start = rng.gen_range(start..end);
+                let range_end_offset = range_start + constants::MIN_RANGE_SIZE;
+                if range_end_offset >= end {
+                    range = Some(Key::from_i128(range_start)..Key::from_i128(end));
+                } else {
+                    let range_end = rng.gen_range((range_start + constants::MIN_RANGE_SIZE)..end);
+                    range = Some(Key::from_i128(range_start)..Key::from_i128(range_end));
+                }
+            }
+            keyspace.ranges.push(range.unwrap());
+        }
+
+        keyspace
+    }
+
+    #[tokio::test]
+    async fn test_delta_layer_vectored_read_end_to_end() -> anyhow::Result<()> {
+        let harness = TenantHarness::create("test_delta_layer_oversized_vectored_read")?;
+        let (tenant, ctx) = harness.load().await;
+
+        let timeline_id = TimelineId::generate();
+        let timeline = tenant
+            .create_test_timeline(timeline_id, constants::LSN_OFFSET, DEFAULT_PG_VERSION, &ctx)
+            .await?;
+
+        tracing::info!("Generating test data ...");
+
+        let rng = &mut StdRng::seed_from_u64(0);
+        let entries = generate_entries(rng);
+        let entries_meta = get_entries_meta(&entries);
+
+        tracing::info!("Done generating {} entries", entries.len());
+
+        tracing::info!("Writing test data to delta layer ...");
+        let mut writer = DeltaLayerWriter::new(
+            harness.conf,
+            timeline_id,
+            harness.tenant_shard_id,
+            entries_meta.key_range.start,
+            entries_meta.lsn_range.clone(),
+        )
+        .await?;
+
+        for entry in entries {
+            let (_, res) = writer
+                .put_value_bytes(entry.key, entry.lsn, entry.value, false)
+                .await;
+            res?;
+        }
+
+        let resident = writer.finish(entries_meta.key_range.end, &timeline).await?;
+
+        let inner = resident.get_inner_delta(&ctx).await?;
+
+        let file_size = inner.file.metadata().await?.len();
+        tracing::info!(
+            "Done writing test data to delta layer. Resulting file size is: {}",
+            file_size
+        );
+
+        for i in 0..constants::READS_COUNT {
+            tracing::info!("Doing vectored read {}/{}", i + 1, constants::READS_COUNT);
+
+            let block_reader = FileBlockReader::new(&inner.file, inner.file_id);
+            let index_reader = DiskBtreeReader::<_, DELTA_KEY_SIZE>::new(
+                inner.index_start_blk,
+                inner.index_root_blk,
+                block_reader,
+            );
+
+            let planner = VectoredReadPlanner::new(constants::MAX_VECTORED_READ_BYTES);
+            let mut reconstruct_state = ValuesReconstructState::new();
+            let keyspace = pick_random_keyspace(rng, &entries_meta.key_range);
+            let data_end_offset = inner.index_start_blk as u64 * PAGE_SZ as u64;
+
+            let vectored_reads = DeltaLayerInner::plan_reads(
+                keyspace.clone(),
+                entries_meta.lsn_range.clone(),
+                data_end_offset,
+                index_reader,
+                planner,
+                &mut reconstruct_state,
+                &ctx,
+            )
+            .await?;
+
+            let vectored_blob_reader = VectoredBlobReader::new(&inner.file);
+            let buf_size = DeltaLayerInner::get_min_read_buffer_size(
+                &vectored_reads,
+                constants::MAX_VECTORED_READ_BYTES,
+            );
+            let mut buf = Some(BytesMut::with_capacity(buf_size));
+
+            for read in vectored_reads {
+                let blobs_buf = vectored_blob_reader
+                    .read_blobs(&read, buf.take().expect("Should have a buffer"))
+                    .await?;
+                for meta in blobs_buf.blobs.iter() {
+                    let value = &blobs_buf.buf[meta.start..meta.end];
+                    assert_eq!(value, entries_meta.index[&(meta.meta.key, meta.meta.lsn)]);
+                }
+
+                buf = Some(blobs_buf.buf);
+            }
+        }
+
+        Ok(())
+    }
 }
@@ -44,6 +44,7 @@ use anyhow::{anyhow, bail, ensure, Context, Result};
 use bytes::{Bytes, BytesMut};
 use camino::{Utf8Path, Utf8PathBuf};
 use hex;
+use itertools::Itertools;
 use pageserver_api::keyspace::KeySpace;
 use pageserver_api::models::LayerAccessKind;
 use pageserver_api::shard::TenantShardId;
@@ -540,7 +541,25 @@ impl ImageLayerInner {

        let vectored_blob_reader = VectoredBlobReader::new(&self.file);
        for read in reads.into_iter() {
-            let buf = BytesMut::with_capacity(max_vectored_read_bytes);
+            let buf_size = read.size();
+
+            if buf_size > max_vectored_read_bytes {
+                // If the read is oversized, it should only contain one key.
+                let offenders = read
+                    .blobs_at
+                    .as_slice()
+                    .iter()
+                    .map(|(_, blob_meta)| format!("{}@{}", blob_meta.key, blob_meta.lsn))
+                    .join(", ");
+                tracing::warn!(
+                    "Oversized vectored read ({} > {}) for keys {}",
+                    buf_size,
+                    max_vectored_read_bytes,
+                    offenders
+                );
+            }
+
+            let buf = BytesMut::with_capacity(buf_size);
            let res = vectored_blob_reader.read_blobs(&read, buf).await;

            match res {
@@ -12,7 +12,7 @@ use crate::tenant::ephemeral_file::EphemeralFile;
 use crate::tenant::storage_layer::ValueReconstructResult;
 use crate::tenant::timeline::GetVectoredError;
 use crate::tenant::{PageReconstructError, Timeline};
-use crate::walrecord;
+use crate::{page_cache, walrecord};
 use anyhow::{anyhow, ensure, Result};
 use pageserver_api::keyspace::KeySpace;
 use pageserver_api::models::InMemoryLayerInfo;
@@ -23,8 +23,12 @@ use tracing::*;
 use utils::{bin_ser::BeSer, id::TimelineId, lsn::Lsn, vec_map::VecMap};
 // avoid binding to Write (conflicts with std::io::Write)
 // while being able to use std::fmt::Write's methods
+use crate::metrics::TIMELINE_EPHEMERAL_BYTES;
+use std::cmp::Ordering;
 use std::fmt::Write as _;
 use std::ops::Range;
+use std::sync::atomic::Ordering as AtomicOrdering;
+use std::sync::atomic::{AtomicU64, AtomicUsize};
 use tokio::sync::{RwLock, RwLockWriteGuard};

 use super::{
@@ -32,10 +36,14 @@ use super::{
    ValuesReconstructState,
 };

+#[derive(Debug, PartialEq, Eq, Clone, Copy, Hash)]
+pub(crate) struct InMemoryLayerFileId(page_cache::FileId);
+
 pub struct InMemoryLayer {
    conf: &'static PageServerConf,
    tenant_shard_id: TenantShardId,
    timeline_id: TimelineId,
+    file_id: InMemoryLayerFileId,

    /// This layer contains all the changes from 'start_lsn'. The
    /// start is inclusive.
@@ -70,6 +78,8 @@ pub struct InMemoryLayerInner {
    /// Each serialized Value is preceded by a 'u32' length field.
    /// PerSeg::page_versions map stores offsets into this file.
    file: EphemeralFile,
+
+    resource_units: GlobalResourceUnits,
 }

 impl std::fmt::Debug for InMemoryLayerInner {
@@ -78,7 +88,126 @@ impl std::fmt::Debug for InMemoryLayerInner {
    }
 }

+/// State shared by all in-memory (ephemeral) layers.  Updated infrequently during background ticks in Timeline,
+/// to minimize contention.
+///
+/// This global state is used to implement behaviors that require a global view of the system, e.g.
+/// rolling layers proactively to limit the total amount of dirty data.
+pub(crate) struct GlobalResources {
+    // Limit on how high dirty_bytes may grow before we start freezing layers to reduce it.
+    // Zero means unlimited.
+    pub(crate) max_dirty_bytes: AtomicU64,
+    // How many bytes are in all EphemeralFile objects
+    dirty_bytes: AtomicU64,
+    // How many layers are contributing to dirty_bytes
+    dirty_layers: AtomicUsize,
+}
+
+// Per-timeline RAII struct for its contribution to [`GlobalResources`]
+struct GlobalResourceUnits {
+    // How many dirty bytes have I added to the global dirty_bytes: this guard object is responsible
+    // for decrementing the global counter by this many bytes when dropped.
+    dirty_bytes: u64,
+}
+
+impl GlobalResourceUnits {
+    // Hint for the layer append path to update us when the layer size differs from the last
+    // call to update_size by this much.  If we don't reach this threshold, we'll still get
+    // updated when the Timeline "ticks" in the background.
+    const MAX_SIZE_DRIFT: u64 = 10 * 1024 * 1024;
+
+    fn new() -> Self {
+        GLOBAL_RESOURCES
+            .dirty_layers
+            .fetch_add(1, AtomicOrdering::Relaxed);
+        Self { dirty_bytes: 0 }
+    }
+
+    /// Do not call this frequently: all timelines will write to these same global atomics,
+    /// so this is a relatively expensive operation.  Wait at least a few seconds between calls.
+    ///
+    /// Returns the effective layer size limit that should be applied, if any, to keep
+    /// the total number of dirty bytes below the configured maximum.
+    fn publish_size(&mut self, size: u64) -> Option<u64> {
+        let new_global_dirty_bytes = match size.cmp(&self.dirty_bytes) {
+            Ordering::Equal => GLOBAL_RESOURCES.dirty_bytes.load(AtomicOrdering::Relaxed),
+            Ordering::Greater => {
+                let delta = size - self.dirty_bytes;
+                let old = GLOBAL_RESOURCES
+                    .dirty_bytes
+                    .fetch_add(delta, AtomicOrdering::Relaxed);
+                old + delta
+            }
+            Ordering::Less => {
+                let delta = self.dirty_bytes - size;
+                let old = GLOBAL_RESOURCES
+                    .dirty_bytes
+                    .fetch_sub(delta, AtomicOrdering::Relaxed);
+                old - delta
+            }
+        };
+
+        // This is a sloppy update: concurrent updates to the counter will race, and the exact
+        // value of the metric might not be the exact latest value of GLOBAL_RESOURCES::dirty_bytes.
+        // That's okay: as long as the metric contains some recent value, it doesn't have to always
+        // be literally the last update.
+        TIMELINE_EPHEMERAL_BYTES.set(new_global_dirty_bytes);
+
+        self.dirty_bytes = size;
+
+        let max_dirty_bytes = GLOBAL_RESOURCES
+            .max_dirty_bytes
+            .load(AtomicOrdering::Relaxed);
+        if max_dirty_bytes > 0 && new_global_dirty_bytes > max_dirty_bytes {
+            // Set the layer file limit to the average layer size: this implies that all above-average
+            // sized layers will be elegible for freezing.  They will be frozen in the order they
+            // next enter publish_size.
+            Some(
+                new_global_dirty_bytes
+                    / GLOBAL_RESOURCES.dirty_layers.load(AtomicOrdering::Relaxed) as u64,
+            )
+        } else {
+            None
+        }
+    }
+
+    // Call publish_size if the input size differs from last published size by more than
+    // the drift limit
+    fn maybe_publish_size(&mut self, size: u64) {
+        let publish = match size.cmp(&self.dirty_bytes) {
+            Ordering::Equal => false,
+            Ordering::Greater => size - self.dirty_bytes > Self::MAX_SIZE_DRIFT,
+            Ordering::Less => self.dirty_bytes - size > Self::MAX_SIZE_DRIFT,
+        };
+
+        if publish {
+            self.publish_size(size);
+        }
+    }
+}
+
+impl Drop for GlobalResourceUnits {
+    fn drop(&mut self) {
+        GLOBAL_RESOURCES
+            .dirty_layers
+            .fetch_sub(1, AtomicOrdering::Relaxed);
+
+        // Subtract our contribution to the global total dirty bytes
+        self.publish_size(0);
+    }
+}
+
+pub(crate) static GLOBAL_RESOURCES: GlobalResources = GlobalResources {
+    max_dirty_bytes: AtomicU64::new(0),
+    dirty_bytes: AtomicU64::new(0),
+    dirty_layers: AtomicUsize::new(0),
+};
+
 impl InMemoryLayer {
+    pub(crate) fn file_id(&self) -> InMemoryLayerFileId {
+        self.file_id
+    }
+
    pub(crate) fn get_timeline_id(&self) -> TimelineId {
        self.timeline_id
    }
@@ -93,6 +222,10 @@ impl InMemoryLayer {
        }
    }

+    pub(crate) fn try_len(&self) -> Option<u64> {
+        self.inner.try_read().map(|i| i.file.len()).ok()
+    }
+
    pub(crate) fn assert_writable(&self) {
        assert!(self.end_lsn.get().is_none());
    }
@@ -318,8 +451,10 @@ impl InMemoryLayer {
        trace!("initializing new empty InMemoryLayer for writing on timeline {timeline_id} at {start_lsn}");

        let file = EphemeralFile::create(conf, tenant_shard_id, timeline_id).await?;
+        let key = InMemoryLayerFileId(file.id());

        Ok(InMemoryLayer {
+            file_id: key,
            conf,
            timeline_id,
            tenant_shard_id,
@@ -328,6 +463,7 @@ impl InMemoryLayer {
            inner: RwLock::new(InMemoryLayerInner {
                index: HashMap::new(),
                file,
+                resource_units: GlobalResourceUnits::new(),
            }),
        })
    }
@@ -378,9 +514,18 @@ impl InMemoryLayer {
            warn!("Key {} at {} already exists", key, lsn);
        }

+        let size = locked_inner.file.len();
+        locked_inner.resource_units.maybe_publish_size(size);
+
        Ok(())
    }

+    pub(crate) async fn tick(&self) -> Option<u64> {
+        let mut inner = self.inner.write().await;
+        let size = inner.file.len();
+        inner.resource_units.publish_size(size)
+    }
+
    pub(crate) async fn put_tombstones(&self, _key_ranges: &[(Range<Key>, Lsn)]) -> Result<()> {
        // TODO: Currently, we just leak the storage for any deleted keys
        Ok(())
@@ -0,0 +1,119 @@
+//! failpoints for unit tests, implying `#[cfg(test)]`.
+//!
+//! These are not accessible over http.
+
+use super::*;
+
+impl Layer {
+    /// Enable a failpoint from a unit test.
+    pub(super) fn enable_failpoint(&self, failpoint: Failpoint) {
+        self.0.failpoints.lock().unwrap().push(failpoint);
+    }
+}
+
+impl LayerInner {
+    /// Query if this failpoint is enabled, as in, arrive at a failpoint.
+    ///
+    /// Calls to this method need to be `#[cfg(test)]` guarded.
+    pub(super) async fn failpoint(&self, kind: FailpointKind) -> Result<(), FailpointHit> {
+        let fut = {
+            let mut fps = self.failpoints.lock().unwrap();
+            // find the *last* failpoint for cases in which we need to use multiple for the same
+            // thing (two blocked evictions)
+            let fp = fps.iter_mut().rfind(|x| x.kind() == kind);
+
+            let Some(fp) = fp else {
+                return Ok(());
+            };
+
+            fp.hit()
+        };
+
+        fut.await
+    }
+}
+
+#[derive(Debug, PartialEq, Eq)]
+pub(crate) enum FailpointKind {
+    /// Failpoint acts as an accurate cancelled by drop here; see the only site of use.
+    AfterDeterminingLayerNeedsNoDownload,
+    /// Failpoint for stalling eviction starting
+    WaitBeforeStartingEvicting,
+    /// Failpoint hit in the spawned task
+    WaitBeforeDownloading,
+}
+
+pub(crate) enum Failpoint {
+    AfterDeterminingLayerNeedsNoDownload,
+    WaitBeforeStartingEvicting(
+        Option<utils::completion::Completion>,
+        utils::completion::Barrier,
+    ),
+    WaitBeforeDownloading(
+        Option<utils::completion::Completion>,
+        utils::completion::Barrier,
+    ),
+}
+
+impl Failpoint {
+    fn kind(&self) -> FailpointKind {
+        match self {
+            Failpoint::AfterDeterminingLayerNeedsNoDownload => {
+                FailpointKind::AfterDeterminingLayerNeedsNoDownload
+            }
+            Failpoint::WaitBeforeStartingEvicting(..) => FailpointKind::WaitBeforeStartingEvicting,
+            Failpoint::WaitBeforeDownloading(..) => FailpointKind::WaitBeforeDownloading,
+        }
+    }
+
+    fn hit(&mut self) -> impl std::future::Future<Output = Result<(), FailpointHit>> + 'static {
+        use futures::future::FutureExt;
+
+        // use boxed futures to avoid Either hurdles
+        match self {
+            Failpoint::AfterDeterminingLayerNeedsNoDownload => {
+                let kind = self.kind();
+
+                async move { Err(FailpointHit(kind)) }.boxed()
+            }
+            Failpoint::WaitBeforeStartingEvicting(arrival, b)
+            | Failpoint::WaitBeforeDownloading(arrival, b) => {
+                // first one signals arrival
+                drop(arrival.take());
+
+                let b = b.clone();
+
+                async move {
+                    tracing::trace!("waiting on a failpoint barrier");
+                    b.wait().await;
+                    tracing::trace!("done waiting on a failpoint barrier");
+                    Ok(())
+                }
+                .boxed()
+            }
+        }
+    }
+}
+
+impl std::fmt::Display for FailpointKind {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        std::fmt::Debug::fmt(self, f)
+    }
+}
+
+#[derive(Debug)]
+pub(crate) struct FailpointHit(FailpointKind);
+
+impl std::fmt::Display for FailpointHit {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        std::fmt::Debug::fmt(self, f)
+    }
+}
+
+impl std::error::Error for FailpointHit {}
+
+impl From<FailpointHit> for DownloadError {
+    fn from(value: FailpointHit) -> Self {
+        DownloadError::Failpoint(value.0)
+    }
+}
@@ -1,14 +1,13 @@
-use futures::StreamExt;
 use pageserver_api::key::CONTROLFILE_KEY;
 use tokio::task::JoinSet;
-use tracing::Instrument;
 use utils::{
    completion::{self, Completion},
    id::TimelineId,
 };

+use super::failpoints::{Failpoint, FailpointKind};
 use super::*;
-use crate::{context::DownloadBehavior, task_mgr::BACKGROUND_RUNTIME};
+use crate::context::DownloadBehavior;
 use crate::{task_mgr::TaskKind, tenant::harness::TenantHarness};

 /// Used in tests to advance a future to wanted await point, and not futher.
@@ -21,7 +20,7 @@ const FOREVER: std::time::Duration = std::time::Duration::from_secs(ADVANCE.as_s
 /// Demonstrate the API and resident -> evicted -> resident -> deleted transitions.
 #[tokio::test]
 async fn smoke_test() {
-    let handle = BACKGROUND_RUNTIME.handle();
+    let handle = tokio::runtime::Handle::current();

    let h = TenantHarness::create("smoke_test").unwrap();
    let span = h.span();
@@ -38,7 +37,7 @@ async fn smoke_test() {
    let layer = {
        let mut layers = {
            let layers = timeline.layers.read().await;
-            layers.resident_layers().collect::<Vec<_>>().await
+            layers.likely_resident_layers().collect::<Vec<_>>()
        };

        assert_eq!(layers.len(), 1);
@@ -88,7 +87,7 @@ async fn smoke_test() {
    //
    // ZERO for timeout does not work reliably, so first take up all spawn_blocking slots to
    // artificially slow it down.
-    let helper = SpawnBlockingPoolHelper::consume_all_spawn_blocking_threads(handle).await;
+    let helper = SpawnBlockingPoolHelper::consume_all_spawn_blocking_threads(&handle).await;

    match layer
        .evict_and_wait(std::time::Duration::ZERO)
@@ -99,7 +98,7 @@ async fn smoke_test() {
            // expected, but note that the eviction is "still ongoing"
            helper.release().await;
            // exhaust spawn_blocking pool to ensure it is now complete
-            SpawnBlockingPoolHelper::consume_and_release_all_of_spawn_blocking_threads(handle)
+            SpawnBlockingPoolHelper::consume_and_release_all_of_spawn_blocking_threads(&handle)
                .await;
        }
        other => unreachable!("{other:?}"),
@@ -108,7 +107,7 @@ async fn smoke_test() {
    // only way to query if a layer is resident is to acquire a ResidentLayer instance.
    // Layer::keep_resident never downloads, but it might initialize if the layer file is found
    // downloaded locally.
-    let none = layer.keep_resident().await.unwrap();
+    let none = layer.keep_resident().await;
    assert!(
        none.is_none(),
        "Expected none, because eviction removed the local file, found: {none:?}"
@@ -167,6 +166,7 @@ async fn smoke_test() {
    rtc.wait_completion().await.unwrap();

    assert_eq!(rtc.get_remote_physical_size(), 0);
+    assert_eq!(0, LAYER_IMPL_METRICS.inits_cancelled.get())
 }

 /// This test demonstrates a previous hang when a eviction and deletion were requested at the same
@@ -174,7 +174,7 @@ async fn smoke_test() {
 #[tokio::test(start_paused = true)]
 async fn evict_and_wait_on_wanted_deleted() {
    // this is the runtime on which Layer spawns the blocking tasks on
-    let handle = BACKGROUND_RUNTIME.handle();
+    let handle = tokio::runtime::Handle::current();

    let h = TenantHarness::create("evict_and_wait_on_wanted_deleted").unwrap();
    utils::logging::replace_panic_hook_with_tracing_panic_hook().forget();
@@ -188,7 +188,7 @@ async fn evict_and_wait_on_wanted_deleted() {
    let layer = {
        let mut layers = {
            let layers = timeline.layers.read().await;
-            layers.resident_layers().collect::<Vec<_>>().await
+            layers.likely_resident_layers().collect::<Vec<_>>()
        };

        assert_eq!(layers.len(), 1);
@@ -213,11 +213,11 @@ async fn evict_and_wait_on_wanted_deleted() {
        drop(resident);

        // make sure the eviction task gets to run
-        SpawnBlockingPoolHelper::consume_and_release_all_of_spawn_blocking_threads(handle).await;
+        SpawnBlockingPoolHelper::consume_and_release_all_of_spawn_blocking_threads(&handle).await;

        let resident = layer.keep_resident().await;
        assert!(
-            matches!(resident, Ok(None)),
+            resident.is_none(),
            "keep_resident should not have re-initialized: {resident:?}"
        );

@@ -235,24 +235,332 @@ async fn evict_and_wait_on_wanted_deleted() {
        layers.finish_gc_timeline(&[layer]);
    }

-    SpawnBlockingPoolHelper::consume_and_release_all_of_spawn_blocking_threads(handle).await;
+    SpawnBlockingPoolHelper::consume_and_release_all_of_spawn_blocking_threads(&handle).await;

    assert_eq!(1, LAYER_IMPL_METRICS.started_deletes.get());
    assert_eq!(1, LAYER_IMPL_METRICS.completed_deletes.get());
    assert_eq!(1, LAYER_IMPL_METRICS.started_evictions.get());
    assert_eq!(1, LAYER_IMPL_METRICS.completed_evictions.get());
+    assert_eq!(0, LAYER_IMPL_METRICS.inits_cancelled.get())
 }

-/// This test shows that ensures we are able to read the layer while the layer eviction has been
-/// started but not completed due to spawn_blocking pool being blocked.
-///
-/// Here `Layer::keep_resident` is used to "simulate" reads, because it cannot download.
-#[tokio::test(start_paused = true)]
-async fn residency_check_while_evict_and_wait_on_clogged_spawn_blocking() {
-    // this is the runtime on which Layer spawns the blocking tasks on
-    let handle = BACKGROUND_RUNTIME.handle();
-    let h = TenantHarness::create("residency_check_while_evict_and_wait_on_clogged_spawn_blocking")
+/// This test ensures we are able to read the layer while the layer eviction has been
+/// started but not completed.
+#[test]
+fn read_wins_pending_eviction() {
+    let rt = tokio::runtime::Builder::new_current_thread()
+        .max_blocking_threads(1)
+        .enable_all()
+        .start_paused(true)
+        .build()
        .unwrap();
+
+    rt.block_on(async move {
+        // this is the runtime on which Layer spawns the blocking tasks on
+        let handle = tokio::runtime::Handle::current();
+        let h = TenantHarness::create("read_wins_pending_eviction").unwrap();
+        let (tenant, ctx) = h.load().await;
+        let span = h.span();
+        let download_span = span.in_scope(|| tracing::info_span!("downloading", timeline_id = 1));
+
+        let timeline = tenant
+            .create_test_timeline(TimelineId::generate(), Lsn(0x10), 14, &ctx)
+            .await
+            .unwrap();
+
+        let layer = {
+            let mut layers = {
+                let layers = timeline.layers.read().await;
+                layers.likely_resident_layers().collect::<Vec<_>>()
+            };
+
+            assert_eq!(layers.len(), 1);
+
+            layers.swap_remove(0)
+        };
+
+        // setup done
+
+        let resident = layer.keep_resident().await.unwrap();
+
+        let mut evict_and_wait = std::pin::pin!(layer.evict_and_wait(FOREVER));
+
+        // drive the future to await on the status channel
+        tokio::time::timeout(ADVANCE, &mut evict_and_wait)
+            .await
+            .expect_err("should had been a timeout since we are holding the layer resident");
+        assert_eq!(1, LAYER_IMPL_METRICS.started_evictions.get());
+
+        let (completion, barrier) = utils::completion::channel();
+        let (arrival, arrived_at_barrier) = utils::completion::channel();
+        layer.enable_failpoint(Failpoint::WaitBeforeStartingEvicting(
+            Some(arrival),
+            barrier,
+        ));
+
+        // now the eviction cannot proceed because the threads are consumed while completion exists
+        drop(resident);
+        arrived_at_barrier.wait().await;
+        assert!(!layer.is_likely_resident());
+
+        // because no actual eviction happened, we get to just reinitialize the DownloadedLayer
+        layer
+            .0
+            .get_or_maybe_download(false, None)
+            .instrument(download_span)
+            .await
+            .expect("should had reinitialized without downloading");
+
+        assert!(layer.is_likely_resident());
+
+        // reinitialization notifies of new resident status, which should error out all evict_and_wait
+        let e = tokio::time::timeout(ADVANCE, &mut evict_and_wait)
+            .await
+            .expect("no timeout, because get_or_maybe_download re-initialized")
+            .expect_err("eviction should not have succeeded because re-initialized");
+
+        // works as intended: evictions lose to "downloads"
+        assert!(matches!(e, EvictionError::Downloaded), "{e:?}");
+        assert_eq!(0, LAYER_IMPL_METRICS.completed_evictions.get());
+
+        // this is not wrong: the eviction is technically still "on the way" as it's still queued
+        // because of a failpoint
+        assert_eq!(
+            0,
+            LAYER_IMPL_METRICS
+                .cancelled_evictions
+                .values()
+                .map(|ctr| ctr.get())
+                .sum::<u64>()
+        );
+
+        drop(completion);
+
+        tokio::time::sleep(ADVANCE).await;
+        SpawnBlockingPoolHelper::consume_and_release_all_of_spawn_blocking_threads0(&handle, 1)
+            .await;
+
+        assert_eq!(0, LAYER_IMPL_METRICS.completed_evictions.get());
+
+        // now we finally can observe the original eviction failing
+        // it would had been possible to observe it earlier, but here it is guaranteed to have
+        // happened.
+        assert_eq!(
+            1,
+            LAYER_IMPL_METRICS
+                .cancelled_evictions
+                .values()
+                .map(|ctr| ctr.get())
+                .sum::<u64>()
+        );
+
+        assert_eq!(
+            1,
+            LAYER_IMPL_METRICS.cancelled_evictions[EvictionCancelled::AlreadyReinitialized].get()
+        );
+
+        assert_eq!(0, LAYER_IMPL_METRICS.inits_cancelled.get())
+    });
+}
+
+/// Use failpoint to delay an eviction starting to get a VersionCheckFailed.
+#[test]
+fn multiple_pending_evictions_in_order() {
+    let name = "multiple_pending_evictions_in_order";
+    let in_order = true;
+    multiple_pending_evictions_scenario(name, in_order);
+}
+
+/// Use failpoint to reorder later eviction before first to get a UnexpectedEvictedState.
+#[test]
+fn multiple_pending_evictions_out_of_order() {
+    let name = "multiple_pending_evictions_out_of_order";
+    let in_order = false;
+    multiple_pending_evictions_scenario(name, in_order);
+}
+
+fn multiple_pending_evictions_scenario(name: &'static str, in_order: bool) {
+    let rt = tokio::runtime::Builder::new_current_thread()
+        .max_blocking_threads(1)
+        .enable_all()
+        .start_paused(true)
+        .build()
+        .unwrap();
+
+    rt.block_on(async move {
+        // this is the runtime on which Layer spawns the blocking tasks on
+        let handle = tokio::runtime::Handle::current();
+        let h = TenantHarness::create(name).unwrap();
+        let (tenant, ctx) = h.load().await;
+        let span = h.span();
+        let download_span = span.in_scope(|| tracing::info_span!("downloading", timeline_id = 1));
+
+        let timeline = tenant
+            .create_test_timeline(TimelineId::generate(), Lsn(0x10), 14, &ctx)
+            .await
+            .unwrap();
+
+        let layer = {
+            let mut layers = {
+                let layers = timeline.layers.read().await;
+                layers.likely_resident_layers().collect::<Vec<_>>()
+            };
+
+            assert_eq!(layers.len(), 1);
+
+            layers.swap_remove(0)
+        };
+
+        // setup done
+
+        let resident = layer.keep_resident().await.unwrap();
+
+        let mut evict_and_wait = std::pin::pin!(layer.evict_and_wait(FOREVER));
+
+        // drive the future to await on the status channel
+        tokio::time::timeout(ADVANCE, &mut evict_and_wait)
+            .await
+            .expect_err("should had been a timeout since we are holding the layer resident");
+        assert_eq!(1, LAYER_IMPL_METRICS.started_evictions.get());
+
+        let (completion1, barrier) = utils::completion::channel();
+        let mut completion1 = Some(completion1);
+        let (arrival, arrived_at_barrier) = utils::completion::channel();
+        layer.enable_failpoint(Failpoint::WaitBeforeStartingEvicting(
+            Some(arrival),
+            barrier,
+        ));
+
+        // now the eviction cannot proceed because we are simulating arbitrary long delay for the
+        // eviction task start.
+        drop(resident);
+        assert!(!layer.is_likely_resident());
+
+        arrived_at_barrier.wait().await;
+
+        // because no actual eviction happened, we get to just reinitialize the DownloadedLayer
+        layer
+            .0
+            .get_or_maybe_download(false, None)
+            .instrument(download_span)
+            .await
+            .expect("should had reinitialized without downloading");
+
+        assert!(layer.is_likely_resident());
+
+        // reinitialization notifies of new resident status, which should error out all evict_and_wait
+        let e = tokio::time::timeout(ADVANCE, &mut evict_and_wait)
+            .await
+            .expect("no timeout, because get_or_maybe_download re-initialized")
+            .expect_err("eviction should not have succeeded because re-initialized");
+
+        // works as intended: evictions lose to "downloads"
+        assert!(matches!(e, EvictionError::Downloaded), "{e:?}");
+        assert_eq!(0, LAYER_IMPL_METRICS.completed_evictions.get());
+
+        // this is not wrong: the eviction is technically still "on the way" as it's still queued
+        // because of a failpoint
+        assert_eq!(
+            0,
+            LAYER_IMPL_METRICS
+                .cancelled_evictions
+                .values()
+                .map(|ctr| ctr.get())
+                .sum::<u64>()
+        );
+
+        assert_eq!(0, LAYER_IMPL_METRICS.completed_evictions.get());
+
+        // configure another failpoint for the second eviction -- evictions are per initialization,
+        // so now that we've reinitialized the inner, we get to run two of them at the same time.
+        let (completion2, barrier) = utils::completion::channel();
+        let (arrival, arrived_at_barrier) = utils::completion::channel();
+        layer.enable_failpoint(Failpoint::WaitBeforeStartingEvicting(
+            Some(arrival),
+            barrier,
+        ));
+
+        let mut second_eviction = std::pin::pin!(layer.evict_and_wait(FOREVER));
+
+        // advance to the wait on the queue
+        tokio::time::timeout(ADVANCE, &mut second_eviction)
+            .await
+            .expect_err("timeout because failpoint is blocking");
+
+        arrived_at_barrier.wait().await;
+
+        assert_eq!(2, LAYER_IMPL_METRICS.started_evictions.get());
+
+        let mut release_earlier_eviction = |expected_reason| {
+            assert_eq!(
+                0,
+                LAYER_IMPL_METRICS.cancelled_evictions[expected_reason].get(),
+            );
+
+            drop(completion1.take().unwrap());
+
+            let handle = &handle;
+
+            async move {
+                tokio::time::sleep(ADVANCE).await;
+                SpawnBlockingPoolHelper::consume_and_release_all_of_spawn_blocking_threads0(
+                    handle, 1,
+                )
+                .await;
+
+                assert_eq!(
+                    1,
+                    LAYER_IMPL_METRICS.cancelled_evictions[expected_reason].get(),
+                );
+            }
+        };
+
+        if in_order {
+            release_earlier_eviction(EvictionCancelled::VersionCheckFailed).await;
+        }
+
+        // release the later eviction which is for the current version
+        drop(completion2);
+        tokio::time::sleep(ADVANCE).await;
+        SpawnBlockingPoolHelper::consume_and_release_all_of_spawn_blocking_threads0(&handle, 1)
+            .await;
+
+        if !in_order {
+            release_earlier_eviction(EvictionCancelled::UnexpectedEvictedState).await;
+        }
+
+        tokio::time::timeout(ADVANCE, &mut second_eviction)
+            .await
+            .expect("eviction goes through now that spawn_blocking is unclogged")
+            .expect("eviction should succeed, because version matches");
+
+        assert_eq!(1, LAYER_IMPL_METRICS.completed_evictions.get());
+
+        // ensure the cancelled are unchanged
+        assert_eq!(
+            1,
+            LAYER_IMPL_METRICS
+                .cancelled_evictions
+                .values()
+                .map(|ctr| ctr.get())
+                .sum::<u64>()
+        );
+
+        assert_eq!(0, LAYER_IMPL_METRICS.inits_cancelled.get())
+    });
+}
+
+/// The test ensures with a failpoint that a pending eviction is not cancelled by what is currently
+/// a `Layer::keep_resident` call.
+///
+/// This matters because cancelling the eviction would leave us in a state where the file is on
+/// disk but the layer internal state says it has not been initialized. Futhermore, it allows us to
+/// have non-repairing `Layer::is_likely_resident`.
+#[tokio::test(start_paused = true)]
+async fn cancelled_get_or_maybe_download_does_not_cancel_eviction() {
+    let handle = tokio::runtime::Handle::current();
+    let h =
+        TenantHarness::create("cancelled_get_or_maybe_download_does_not_cancel_eviction").unwrap();
    let (tenant, ctx) = h.load().await;

    let timeline = tenant
@@ -263,7 +571,7 @@ async fn residency_check_while_evict_and_wait_on_clogged_spawn_blocking() {
    let layer = {
        let mut layers = {
            let layers = timeline.layers.read().await;
-            layers.resident_layers().collect::<Vec<_>>().await
+            layers.likely_resident_layers().collect::<Vec<_>>()
        };

        assert_eq!(layers.len(), 1);
@@ -271,90 +579,154 @@ async fn residency_check_while_evict_and_wait_on_clogged_spawn_blocking() {
        layers.swap_remove(0)
    };

-    // setup done
+    // this failpoint will simulate the `get_or_maybe_download` becoming cancelled (by returning an
+    // Err) at the right time as in "during" the `LayerInner::needs_download`.
+    layer.enable_failpoint(Failpoint::AfterDeterminingLayerNeedsNoDownload);

-    let resident = layer.keep_resident().await.unwrap();
+    let (completion, barrier) = utils::completion::channel();
+    let (arrival, arrived_at_barrier) = utils::completion::channel();
+
+    layer.enable_failpoint(Failpoint::WaitBeforeStartingEvicting(
+        Some(arrival),
+        barrier,
+    ));
+
+    tokio::time::timeout(ADVANCE, layer.evict_and_wait(FOREVER))
+        .await
+        .expect_err("should had advanced to waiting on channel");
+
+    arrived_at_barrier.wait().await;
+
+    // simulate a cancelled read which is cancelled before it gets to re-initialize
+    let e = layer
+        .0
+        .get_or_maybe_download(false, None)
+        .await
+        .unwrap_err();
+    assert!(
+        matches!(
+            e,
+            DownloadError::Failpoint(FailpointKind::AfterDeterminingLayerNeedsNoDownload)
+        ),
+        "{e:?}"
+    );
+
+    assert!(
+        layer.0.needs_download().await.unwrap().is_none(),
+        "file is still on disk"
+    );
+
+    // release the eviction task
+    drop(completion);
+    tokio::time::sleep(ADVANCE).await;
+    SpawnBlockingPoolHelper::consume_and_release_all_of_spawn_blocking_threads(&handle).await;
+
+    // failpoint is still enabled, but it is not hit
+    let e = layer
+        .0
+        .get_or_maybe_download(false, None)
+        .await
+        .unwrap_err();
+    assert!(matches!(e, DownloadError::DownloadRequired), "{e:?}");
+
+    // failpoint is not counted as cancellation either
+    assert_eq!(0, LAYER_IMPL_METRICS.inits_cancelled.get())
+}
+
+#[tokio::test(start_paused = true)]
+async fn evict_and_wait_does_not_wait_for_download() {
+    // let handle = tokio::runtime::Handle::current();
+    let h = TenantHarness::create("evict_and_wait_does_not_wait_for_download").unwrap();
+    let (tenant, ctx) = h.load().await;
+    let span = h.span();
+    let download_span = span.in_scope(|| tracing::info_span!("downloading", timeline_id = 1));
+
+    let timeline = tenant
+        .create_test_timeline(TimelineId::generate(), Lsn(0x10), 14, &ctx)
+        .await
+        .unwrap();
+
+    let layer = {
+        let mut layers = {
+            let layers = timeline.layers.read().await;
+            layers.likely_resident_layers().collect::<Vec<_>>()
+        };
+
+        assert_eq!(layers.len(), 1);
+
+        layers.swap_remove(0)
+    };
+
+    // kind of forced setup: start an eviction but do not allow it progress until we are
+    // downloading
+    let (eviction_can_continue, barrier) = utils::completion::channel();
+    let (arrival, eviction_arrived) = utils::completion::channel();
+    layer.enable_failpoint(Failpoint::WaitBeforeStartingEvicting(
+        Some(arrival),
+        barrier,
+    ));

    let mut evict_and_wait = std::pin::pin!(layer.evict_and_wait(FOREVER));

-    // drive the future to await on the status channel
+    // use this once-awaited other_evict to synchronize with the eviction
+    let other_evict = layer.evict_and_wait(FOREVER);
+
    tokio::time::timeout(ADVANCE, &mut evict_and_wait)
        .await
-        .expect_err("should had been a timeout since we are holding the layer resident");
-    assert_eq!(1, LAYER_IMPL_METRICS.started_evictions.get());
+        .expect_err("should had advanced");
+    eviction_arrived.wait().await;
+    drop(eviction_can_continue);
+    other_evict.await.unwrap();

-    // clog up BACKGROUND_RUNTIME spawn_blocking
-    let helper = SpawnBlockingPoolHelper::consume_all_spawn_blocking_threads(handle).await;
+    // now the layer is evicted, and the "evict_and_wait" is waiting on the receiver
+    assert!(!layer.is_likely_resident());

-    // now the eviction cannot proceed because the threads are consumed while completion exists
-    drop(resident);
+    // following new evict_and_wait will fail until we've completed the download
+    let e = layer.evict_and_wait(FOREVER).await.unwrap_err();
+    assert!(matches!(e, EvictionError::NotFound), "{e:?}");

-    // because no actual eviction happened, we get to just reinitialize the DownloadedLayer
-    layer
-        .keep_resident()
-        .await
-        .expect("keep_resident should had reinitialized without downloading")
-        .expect("ResidentLayer");
+    let (download_can_continue, barrier) = utils::completion::channel();
+    let (arrival, _download_arrived) = utils::completion::channel();
+    layer.enable_failpoint(Failpoint::WaitBeforeDownloading(Some(arrival), barrier));

-    // because the keep_resident check alters wanted evicted without sending a message, we will
-    // never get completed
-    let e = tokio::time::timeout(ADVANCE, &mut evict_and_wait)
-        .await
-        .expect("no timeout, because keep_resident re-initialized")
-        .expect_err("eviction should not have succeeded because re-initialized");
+    let mut download = std::pin::pin!(layer
+        .0
+        .get_or_maybe_download(true, None)
+        .instrument(download_span));

-    // works as intended: evictions lose to "downloads"
-    assert!(matches!(e, EvictionError::Downloaded), "{e:?}");
-    assert_eq!(0, LAYER_IMPL_METRICS.completed_evictions.get());
-
-    // this is not wrong: the eviction is technically still "on the way" as it's still queued
-    // because spawn_blocking is clogged up
-    assert_eq!(
-        0,
-        LAYER_IMPL_METRICS
-            .cancelled_evictions
-            .values()
-            .map(|ctr| ctr.get())
-            .sum::<u64>()
+    assert!(
+        !layer.is_likely_resident(),
+        "during download layer is evicted"
    );

-    let mut second_eviction = std::pin::pin!(layer.evict_and_wait(FOREVER));
-
-    // advance to the wait on the queue
-    tokio::time::timeout(ADVANCE, &mut second_eviction)
+    tokio::time::timeout(ADVANCE, &mut download)
        .await
-        .expect_err("timeout because spawn_blocking is clogged");
+        .expect_err("should had timed out because of failpoint");

-    // in this case we don't leak started evictions, but I think there is still a chance of that
-    // happening, because we could have upgrades race multiple evictions while only one of them
-    // happens?
-    assert_eq!(2, LAYER_IMPL_METRICS.started_evictions.get());
+    // now we finally get to continue, and because the latest state is downloading, we deduce that
+    // original eviction succeeded
+    evict_and_wait.await.unwrap();

-    helper.release().await;
+    // however a new evict_and_wait will fail
+    let e = layer.evict_and_wait(FOREVER).await.unwrap_err();
+    assert!(matches!(e, EvictionError::NotFound), "{e:?}");

-    // the second_eviction gets to run here
-    //
-    // synchronize to be *strictly* after the second_eviction spawn_blocking run
-    SpawnBlockingPoolHelper::consume_and_release_all_of_spawn_blocking_threads(handle).await;
+    assert!(!layer.is_likely_resident());

-    tokio::time::timeout(ADVANCE, &mut second_eviction)
-        .await
-        .expect("eviction goes through now that spawn_blocking is unclogged")
-        .expect("eviction should succeed, because version matches");
+    drop(download_can_continue);
+    download.await.expect("download should had succeeded");
+    assert!(layer.is_likely_resident());

-    assert_eq!(1, LAYER_IMPL_METRICS.completed_evictions.get());
+    // only now can we evict
+    layer.evict_and_wait(FOREVER).await.unwrap();
+}

-    // now we finally can observe the original spawn_blocking failing
-    // it would had been possible to observe it earlier, but here it is guaranteed to have
-    // happened.
-    assert_eq!(
-        1,
-        LAYER_IMPL_METRICS
-            .cancelled_evictions
-            .values()
-            .map(|ctr| ctr.get())
-            .sum::<u64>()
-    );
+#[test]
+fn layer_size() {
+    assert_eq!(std::mem::size_of::<LayerAccessStats>(), 2040);
+    assert_eq!(std::mem::size_of::<PersistentLayerDesc>(), 104);
+    assert_eq!(std::mem::size_of::<LayerInner>(), 2328);
+    // it also has the utf8 path
 }

 struct SpawnBlockingPoolHelper {
@@ -371,31 +743,41 @@ impl SpawnBlockingPoolHelper {
    ///
    /// This should be no issue nowdays, because nextest runs each test in it's own process.
    async fn consume_all_spawn_blocking_threads(handle: &tokio::runtime::Handle) -> Self {
-        let (completion, barrier) = completion::channel();
-        let (tx, mut rx) = tokio::sync::mpsc::channel(8);
+        let default_max_blocking_threads = 512;

-        let assumed_max_blocking_threads = 512;
+        Self::consume_all_spawn_blocking_threads0(handle, default_max_blocking_threads).await
+    }
+
+    async fn consume_all_spawn_blocking_threads0(
+        handle: &tokio::runtime::Handle,
+        threads: usize,
+    ) -> Self {
+        assert_ne!(threads, 0);
+
+        let (completion, barrier) = completion::channel();
+        let (started, starts_completed) = completion::channel();

        let mut blocking_tasks = JoinSet::new();

-        for _ in 0..assumed_max_blocking_threads {
+        for _ in 0..threads {
            let barrier = barrier.clone();
-            let tx = tx.clone();
+            let started = started.clone();
            blocking_tasks.spawn_blocking_on(
                move || {
-                    tx.blocking_send(()).unwrap();
-                    drop(tx);
+                    drop(started);
                    tokio::runtime::Handle::current().block_on(barrier.wait());
                },
                handle,
            );
        }

+        drop(started);
+
+        starts_completed.wait().await;
+
        drop(barrier);

-        for _ in 0..assumed_max_blocking_threads {
-            rx.recv().await.unwrap();
-        }
+        tracing::trace!("consumed all threads");

        SpawnBlockingPoolHelper {
            awaited_by_spawn_blocking_tasks: completion,
@@ -415,13 +797,22 @@ impl SpawnBlockingPoolHelper {
        while let Some(res) = blocking_tasks.join_next().await {
            res.expect("none of the tasks should had panicked");
        }
+
+        tracing::trace!("released all threads");
    }

    /// In the tests it is used as an easy way of making sure something scheduled on the target
    /// runtimes `spawn_blocking` has completed, because it must've been scheduled and completed
    /// before our tasks have a chance to schedule and complete.
    async fn consume_and_release_all_of_spawn_blocking_threads(handle: &tokio::runtime::Handle) {
-        Self::consume_all_spawn_blocking_threads(handle)
+        Self::consume_and_release_all_of_spawn_blocking_threads0(handle, 512).await
+    }
+
+    async fn consume_and_release_all_of_spawn_blocking_threads0(
+        handle: &tokio::runtime::Handle,
+        threads: usize,
+    ) {
+        Self::consume_all_spawn_blocking_threads0(handle, threads)
            .await
            .release()
            .await
@@ -435,7 +826,7 @@ fn spawn_blocking_pool_helper_actually_works() {
    // because the amount is not configurable for our helper, expect the same amount as
    // BACKGROUND_RUNTIME using the tokio defaults would have.
    let rt = tokio::runtime::Builder::new_current_thread()
-        .max_blocking_threads(512)
+        .max_blocking_threads(1)
        .enable_all()
        .build()
        .unwrap();
@@ -445,7 +836,8 @@ fn spawn_blocking_pool_helper_actually_works() {
    rt.block_on(async move {
        // this will not return until all threads are spun up and actually executing the code
        // waiting on `consumed` to be `SpawnBlockingPoolHelper::release`'d.
-        let consumed = SpawnBlockingPoolHelper::consume_all_spawn_blocking_threads(handle).await;
+        let consumed =
+            SpawnBlockingPoolHelper::consume_all_spawn_blocking_threads0(handle, 1).await;

        println!("consumed");

@@ -125,18 +125,8 @@ impl Timeline {
                    )
                    .await
                    .map_err(anyhow::Error::from)?;
-                if let Some(remote_client) = &self.remote_client {
-                    for layer in layers {
-                        remote_client.schedule_layer_file_upload(layer)?;
-                    }
-                }

-                if let Some(remote_client) = &self.remote_client {
-                    // should any new image layer been created, not uploading index_part will
-                    // result in a mismatch between remote_physical_size and layermap calculated
-                    // size, which will fail some tests, but should not be an issue otherwise.
-                    remote_client.schedule_index_upload_for_file_changes()?;
-                }
+                self.upload_new_image_layers(layers)?;
            }
            Err(err) => {
                // no partitioning? This is normal, if the timeline was just created
@@ -818,7 +808,10 @@ impl TimelineAdaptor {
        self.timeline
            .finish_compact_batch(&self.new_deltas, &self.new_images, &layers_to_delete)
            .await?;
-        self.new_images.clear();
+
+        self.timeline
+            .upload_new_image_layers(std::mem::take(&mut self.new_images))?;
+
        self.new_deltas.clear();
        self.layers_to_delete.clear();
        Ok(())
@@ -6,7 +6,7 @@ use std::{
 use anyhow::Context;
 use pageserver_api::{models::TimelineState, shard::TenantShardId};
 use tokio::sync::OwnedMutexGuard;
-use tracing::{debug, error, info, instrument, Instrument};
+use tracing::{error, info, instrument, Instrument};
 use utils::{crashsafe, fs_ext, id::TimelineId};

 use crate::{
@@ -14,81 +14,14 @@ use crate::{
    deletion_queue::DeletionQueueClient,
    task_mgr::{self, TaskKind},
    tenant::{
-        debug_assert_current_span_has_tenant_and_timeline_id,
        metadata::TimelineMetadata,
-        remote_timeline_client::{
-            self, PersistIndexPartWithDeletedFlagError, RemoteTimelineClient,
-        },
+        remote_timeline_client::{PersistIndexPartWithDeletedFlagError, RemoteTimelineClient},
        CreateTimelineCause, DeleteTimelineError, Tenant,
    },
 };

 use super::{Timeline, TimelineResources};

-/// Now that the Timeline is in Stopping state, request all the related tasks to shut down.
-async fn stop_tasks(timeline: &Timeline) -> Result<(), DeleteTimelineError> {
-    debug_assert_current_span_has_tenant_and_timeline_id();
-    // Notify any timeline work to drop out of loops/requests
-    tracing::debug!("Cancelling CancellationToken");
-    timeline.cancel.cancel();
-
-    // Stop the walreceiver first.
-    debug!("waiting for wal receiver to shutdown");
-    let maybe_started_walreceiver = { timeline.walreceiver.lock().unwrap().take() };
-    if let Some(walreceiver) = maybe_started_walreceiver {
-        walreceiver.stop().await;
-    }
-    debug!("wal receiver shutdown confirmed");
-
-    // Shut down the layer flush task before the remote client, as one depends on the other
-    task_mgr::shutdown_tasks(
-        Some(TaskKind::LayerFlushTask),
-        Some(timeline.tenant_shard_id),
-        Some(timeline.timeline_id),
-    )
-    .await;
-
-    // Prevent new uploads from starting.
-    if let Some(remote_client) = timeline.remote_client.as_ref() {
-        let res = remote_client.stop();
-        match res {
-            Ok(()) => {}
-            Err(e) => match e {
-                remote_timeline_client::StopError::QueueUninitialized => {
-                    // This case shouldn't happen currently because the
-                    // load and attach code bails out if _any_ of the timeline fails to fetch its IndexPart.
-                    // That is, before we declare the Tenant as Active.
-                    // But we only allow calls to delete_timeline on Active tenants.
-                    return Err(DeleteTimelineError::Other(anyhow::anyhow!("upload queue is uninitialized, likely the timeline was in Broken state prior to this call because it failed to fetch IndexPart during load or attach, check the logs")));
-                }
-            },
-        }
-    }
-
-    // Stop & wait for the remaining timeline tasks, including upload tasks.
-    // NB: This and other delete_timeline calls do not run as a task_mgr task,
-    //     so, they are not affected by this shutdown_tasks() call.
-    info!("waiting for timeline tasks to shutdown");
-    task_mgr::shutdown_tasks(
-        None,
-        Some(timeline.tenant_shard_id),
-        Some(timeline.timeline_id),
-    )
-    .await;
-
-    fail::fail_point!("timeline-delete-before-index-deleted-at", |_| {
-        Err(anyhow::anyhow!(
-            "failpoint: timeline-delete-before-index-deleted-at"
-        ))?
-    });
-
-    tracing::debug!("Waiting for gate...");
-    timeline.gate.close().await;
-    tracing::debug!("Shutdown complete");
-
-    Ok(())
-}
-
 /// Mark timeline as deleted in S3 so we won't pick it up next time
 /// during attach or pageserver restart.
 /// See comment in persist_index_part_with_deleted_flag.
@@ -282,7 +215,14 @@ impl DeleteTimelineFlow {

        guard.mark_in_progress()?;

-        stop_tasks(&timeline).await?;
+        // Now that the Timeline is in Stopping state, request all the related tasks to shut down.
+        timeline.shutdown(super::ShutdownMode::Hard).await;
+
+        fail::fail_point!("timeline-delete-before-index-deleted-at", |_| {
+            Err(anyhow::anyhow!(
+                "failpoint: timeline-delete-before-index-deleted-at"
+            ))?
+        });

        set_deleted_in_remote_index(&timeline).await?;

@@ -51,6 +51,7 @@ pub struct EvictionTaskTenantState {
 impl Timeline {
    pub(super) fn launch_eviction_task(
        self: &Arc<Self>,
+        parent: Arc<Tenant>,
        background_tasks_can_start: Option<&completion::Barrier>,
    ) {
        let self_clone = Arc::clone(self);
@@ -66,20 +67,19 @@ impl Timeline {
            ),
            false,
            async move {
-                let cancel = task_mgr::shutdown_token();
                tokio::select! {
-                    _ = cancel.cancelled() => { return Ok(()); }
+                    _ = self_clone.cancel.cancelled() => { return Ok(()); }
                    _ = completion::Barrier::maybe_wait(background_tasks_can_start) => {}
                };

-                self_clone.eviction_task(cancel).await;
+                self_clone.eviction_task(parent).await;
                Ok(())
            },
        );
    }

    #[instrument(skip_all, fields(tenant_id = %self.tenant_shard_id.tenant_id, shard_id = %self.tenant_shard_id.shard_slug(), timeline_id = %self.timeline_id))]
-    async fn eviction_task(self: Arc<Self>, cancel: CancellationToken) {
+    async fn eviction_task(self: Arc<Self>, tenant: Arc<Tenant>) {
        use crate::tenant::tasks::random_init_delay;

        // acquire the gate guard only once within a useful span
@@ -94,7 +94,7 @@ impl Timeline {
                EvictionPolicy::OnlyImitiate(lat) => lat.period,
                EvictionPolicy::NoEviction => Duration::from_secs(10),
            };
-            if random_init_delay(period, &cancel).await.is_err() {
+            if random_init_delay(period, &self.cancel).await.is_err() {
                return;
            }
        }
@@ -103,13 +103,13 @@ impl Timeline {
        loop {
            let policy = self.get_eviction_policy();
            let cf = self
-                .eviction_iteration(&policy, &cancel, &guard, &ctx)
+                .eviction_iteration(&tenant, &policy, &self.cancel, &guard, &ctx)
                .await;

            match cf {
                ControlFlow::Break(()) => break,
                ControlFlow::Continue(sleep_until) => {
-                    if tokio::time::timeout_at(sleep_until, cancel.cancelled())
+                    if tokio::time::timeout_at(sleep_until, self.cancel.cancelled())
                        .await
                        .is_ok()
                    {
@@ -123,6 +123,7 @@ impl Timeline {
    #[instrument(skip_all, fields(policy_kind = policy.discriminant_str()))]
    async fn eviction_iteration(
        self: &Arc<Self>,
+        tenant: &Tenant,
        policy: &EvictionPolicy,
        cancel: &CancellationToken,
        gate: &GateGuard,
@@ -137,7 +138,7 @@ impl Timeline {
            }
            EvictionPolicy::LayerAccessThreshold(p) => {
                match self
-                    .eviction_iteration_threshold(p, cancel, gate, ctx)
+                    .eviction_iteration_threshold(tenant, p, cancel, gate, ctx)
                    .await
                {
                    ControlFlow::Break(()) => return ControlFlow::Break(()),
@@ -146,7 +147,11 @@ impl Timeline {
                (p.period, p.threshold)
            }
            EvictionPolicy::OnlyImitiate(p) => {
-                if self.imitiate_only(p, cancel, gate, ctx).await.is_break() {
+                if self
+                    .imitiate_only(tenant, p, cancel, gate, ctx)
+                    .await
+                    .is_break()
+                {
                    return ControlFlow::Break(());
                }
                (p.period, p.threshold)
@@ -175,6 +180,7 @@ impl Timeline {

    async fn eviction_iteration_threshold(
        self: &Arc<Self>,
+        tenant: &Tenant,
        p: &EvictionPolicyLayerAccessThreshold,
        cancel: &CancellationToken,
        gate: &GateGuard,
@@ -193,7 +199,10 @@ impl Timeline {
            _ = self.cancel.cancelled() => return ControlFlow::Break(()),
        };

-        match self.imitate_layer_accesses(p, cancel, gate, ctx).await {
+        match self
+            .imitate_layer_accesses(tenant, p, cancel, gate, ctx)
+            .await
+        {
            ControlFlow::Break(()) => return ControlFlow::Break(()),
            ControlFlow::Continue(()) => (),
        }
@@ -225,24 +234,18 @@ impl Timeline {
        {
            let guard = self.layers.read().await;
            let layers = guard.layer_map();
-            for hist_layer in layers.iter_historic_layers() {
-                let hist_layer = guard.get_from_desc(&hist_layer);
+            for layer in layers.iter_historic_layers() {
+                let layer = guard.get_from_desc(&layer);

                // guard against eviction while we inspect it; it might be that eviction_task and
                // disk_usage_eviction_task both select the same layers to be evicted, and
                // seemingly free up double the space. both succeeding is of no consequence.
-                let guard = match hist_layer.keep_resident().await {
-                    Ok(Some(l)) => l,
-                    Ok(None) => continue,
-                    Err(e) => {
-                        // these should not happen, but we cannot make them statically impossible right
-                        // now.
-                        tracing::warn!(layer=%hist_layer, "failed to keep the layer resident: {e:#}");
-                        continue;
-                    }
-                };

-                let last_activity_ts = hist_layer.access_stats().latest_activity_or_now();
+                if !layer.is_likely_resident() {
+                    continue;
+                }
+
+                let last_activity_ts = layer.access_stats().latest_activity_or_now();

                let no_activity_for = match now.duration_since(last_activity_ts) {
                    Ok(d) => d,
@@ -265,9 +268,8 @@ impl Timeline {
                        continue;
                    }
                };
-                let layer = guard.drop_eviction_guard();
+
                if no_activity_for > p.threshold {
-                    // this could cause a lot of allocations in some cases
                    js.spawn(async move {
                        layer
                            .evict_and_wait(std::time::Duration::from_secs(5))
@@ -322,6 +324,7 @@ impl Timeline {
    /// disk usage based eviction task.
    async fn imitiate_only(
        self: &Arc<Self>,
+        tenant: &Tenant,
        p: &EvictionPolicyLayerAccessThreshold,
        cancel: &CancellationToken,
        gate: &GateGuard,
@@ -338,7 +341,8 @@ impl Timeline {
            _ = self.cancel.cancelled() => return ControlFlow::Break(()),
        };

-        self.imitate_layer_accesses(p, cancel, gate, ctx).await
+        self.imitate_layer_accesses(tenant, p, cancel, gate, ctx)
+            .await
    }

    /// If we evict layers but keep cached values derived from those layers, then
@@ -368,6 +372,7 @@ impl Timeline {
    #[instrument(skip_all)]
    async fn imitate_layer_accesses(
        &self,
+        tenant: &Tenant,
        p: &EvictionPolicyLayerAccessThreshold,
        cancel: &CancellationToken,
        gate: &GateGuard,
@@ -403,17 +408,11 @@ impl Timeline {
        // Make one of the tenant's timelines draw the short straw and run the calculation.
        // The others wait until the calculation is done so that they take into account the
        // imitated accesses that the winner made.
-        let tenant = match crate::tenant::mgr::get_tenant(self.tenant_shard_id, true) {
-            Ok(t) => t,
-            Err(_) => {
-                return ControlFlow::Break(());
-            }
-        };
        let mut state = tenant.eviction_task_tenant_state.lock().await;
        match state.last_layer_access_imitation {
            Some(ts) if ts.elapsed() < inter_imitate_period => { /* no need to run */ }
            _ => {
-                self.imitate_synthetic_size_calculation_worker(&tenant, cancel, ctx)
+                self.imitate_synthetic_size_calculation_worker(tenant, cancel, ctx)
                    .await;
                state.last_layer_access_imitation = Some(tokio::time::Instant::now());
            }
@@ -487,7 +486,7 @@ impl Timeline {
    #[instrument(skip_all)]
    async fn imitate_synthetic_size_calculation_worker(
        &self,
-        tenant: &Arc<Tenant>,
+        tenant: &Tenant,
        cancel: &CancellationToken,
        ctx: &RequestContext,
    ) {
@@ -1,5 +1,4 @@
 use anyhow::{bail, ensure, Context, Result};
-use futures::StreamExt;
 use pageserver_api::shard::TenantShardId;
 use std::{collections::HashMap, sync::Arc};
 use tracing::trace;
@@ -121,9 +120,10 @@ impl LayerManager {
    /// Called from `freeze_inmem_layer`, returns true if successfully frozen.
    pub(crate) async fn try_freeze_in_memory_layer(
        &mut self,
-        Lsn(last_record_lsn): Lsn,
+        lsn: Lsn,
        last_freeze_at: &AtomicLsn,
    ) {
+        let Lsn(last_record_lsn) = lsn;
        let end_lsn = Lsn(last_record_lsn + 1);

        if let Some(open_layer) = &self.layer_map.open_layer {
@@ -136,8 +136,11 @@ impl LayerManager {
            self.layer_map.frozen_layers.push_back(open_layer_rc);
            self.layer_map.open_layer = None;
            self.layer_map.next_open_layer_at = Some(end_lsn);
-            last_freeze_at.store(end_lsn);
        }
+
+        // Even if there was no layer to freeze, advance last_freeze_at to last_record_lsn+1: this
+        // accounts for regions in the LSN range where we might have ingested no data due to sharding.
+        last_freeze_at.store(end_lsn);
    }

    /// Add image layers to the layer map, called from `create_image_layers`.
@@ -241,29 +244,16 @@ impl LayerManager {
        layer.delete_on_drop();
    }

-    pub(crate) fn resident_layers(&self) -> impl futures::stream::Stream<Item = Layer> + '_ {
+    pub(crate) fn likely_resident_layers(&self) -> impl Iterator<Item = Layer> + '_ {
        // for small layer maps, we most likely have all resident, but for larger more are likely
        // to be evicted assuming lots of layers correlated with longer lifespan.

-        let layers = self
-            .layer_map()
-            .iter_historic_layers()
-            .map(|desc| self.get_from_desc(&desc));
-
-        let layers = futures::stream::iter(layers);
-
-        layers.filter_map(|layer| async move {
-            // TODO(#6028): this query does not really need to see the ResidentLayer
-            match layer.keep_resident().await {
-                Ok(Some(layer)) => Some(layer.drop_eviction_guard()),
-                Ok(None) => None,
-                Err(e) => {
-                    // these should not happen, but we cannot make them statically impossible right
-                    // now.
-                    tracing::warn!(%layer, "failed to keep the layer resident: {e:#}");
-                    None
-                }
-            }
+        self.layer_map().iter_historic_layers().filter_map(|desc| {
+            self.layer_fmgr
+                .0
+                .get(&desc.key())
+                .filter(|l| l.is_likely_resident())
+                .cloned()
        })
    }

@@ -86,6 +86,7 @@ impl<'t> UninitializedTimeline<'t> {
    /// Prepares timeline data by loading it from the basebackup archive.
    pub(crate) async fn import_basebackup_from_tar(
        self,
+        tenant: Arc<Tenant>,
        copyin_read: &mut (impl tokio::io::AsyncRead + Send + Sync + Unpin),
        base_lsn: Lsn,
        broker_client: storage_broker::BrokerClientChannel,
@@ -114,7 +115,7 @@ impl<'t> UninitializedTimeline<'t> {

        // All the data has been imported. Insert the Timeline into the tenant's timelines map
        let tl = self.finish_creation()?;
-        tl.activate(broker_client, None, ctx);
+        tl.activate(tenant, broker_client, None, ctx);
        Ok(tl)
    }

@@ -24,26 +24,21 @@ mod connection_manager;
 mod walreceiver_connection;

 use crate::context::{DownloadBehavior, RequestContext};
-use crate::task_mgr::{self, TaskKind, WALRECEIVER_RUNTIME};
+use crate::task_mgr::{TaskKind, WALRECEIVER_RUNTIME};
 use crate::tenant::debug_assert_current_span_has_tenant_and_timeline_id;
 use crate::tenant::timeline::walreceiver::connection_manager::{
    connection_manager_loop_step, ConnectionManagerState,
 };

-use pageserver_api::shard::TenantShardId;
 use std::future::Future;
 use std::num::NonZeroU64;
-use std::ops::ControlFlow;
 use std::sync::Arc;
 use std::time::Duration;
 use storage_broker::BrokerClientChannel;
-use tokio::select;
 use tokio::sync::watch;
 use tokio_util::sync::CancellationToken;
 use tracing::*;

-use utils::id::TimelineId;
-
 use self::connection_manager::ConnectionManagerStatus;

 use super::Timeline;
@@ -62,9 +57,10 @@ pub struct WalReceiverConf {
 }

 pub struct WalReceiver {
-    tenant_shard_id: TenantShardId,
-    timeline_id: TimelineId,
    manager_status: Arc<std::sync::RwLock<Option<ConnectionManagerStatus>>>,
+    /// All task spawned by [`WalReceiver::start`] and its children are sensitive to this token.
+    /// It's a child token of [`Timeline`] so that timeline shutdown can cancel WalReceiver tasks early for `freeze_and_flush=true`.
+    cancel: CancellationToken,
 }

 impl WalReceiver {
@@ -78,65 +74,58 @@ impl WalReceiver {
        let timeline_id = timeline.timeline_id;
        let walreceiver_ctx =
            ctx.detached_child(TaskKind::WalReceiverManager, DownloadBehavior::Error);
-
        let loop_status = Arc::new(std::sync::RwLock::new(None));
        let manager_status = Arc::clone(&loop_status);
-        task_mgr::spawn(
-            WALRECEIVER_RUNTIME.handle(),
-            TaskKind::WalReceiverManager,
-            Some(timeline.tenant_shard_id),
-            Some(timeline_id),
-            &format!("walreceiver for timeline {tenant_shard_id}/{timeline_id}"),
-            false,
+        let cancel = timeline.cancel.child_token();
+        WALRECEIVER_RUNTIME.spawn({
+            let cancel = cancel.clone();
            async move {
                debug_assert_current_span_has_tenant_and_timeline_id();
+                // acquire timeline gate so we know the task doesn't outlive the Timeline
+                let Ok(_guard) = timeline.gate.enter() else {
+                    debug!("WAL receiver manager could not enter the gate timeline gate, it's closed already");
+                    return;
+                };
                debug!("WAL receiver manager started, connecting to broker");
                let mut connection_manager_state = ConnectionManagerState::new(
                    timeline,
                    conf,
+                    cancel.clone(),
                );
-                loop {
-                    select! {
-                        _ = task_mgr::shutdown_watcher() => {
-                            trace!("WAL receiver shutdown requested, shutting down");
+                while !cancel.is_cancelled() {
+                    let loop_step_result = connection_manager_loop_step(
+                        &mut broker_client,
+                        &mut connection_manager_state,
+                        &walreceiver_ctx,
+                        &cancel,
+                        &loop_status,
+                    ).await;
+                    match loop_step_result {
+                        Ok(()) => continue,
+                        Err(_cancelled) => {
+                            trace!("Connection manager loop ended, shutting down");
                            break;
-                        },
-                        loop_step_result = connection_manager_loop_step(
-                            &mut broker_client,
-                            &mut connection_manager_state,
-                            &walreceiver_ctx,
-                            &loop_status,
-                        ) => match loop_step_result {
-                            ControlFlow::Continue(()) => continue,
-                            ControlFlow::Break(()) => {
-                                trace!("Connection manager loop ended, shutting down");
-                                break;
-                            }
-                        },
+                        }
                    }
                }
-
                connection_manager_state.shutdown().await;
                *loop_status.write().unwrap() = None;
-                Ok(())
+                debug!("task exits");
            }
            .instrument(info_span!(parent: None, "wal_connection_manager", tenant_id = %tenant_shard_id.tenant_id, shard_id = %tenant_shard_id.shard_slug(), timeline_id = %timeline_id))
-        );
+        });

        Self {
-            tenant_shard_id,
-            timeline_id,
            manager_status,
+            cancel,
        }
    }

-    pub async fn stop(self) {
-        task_mgr::shutdown_tasks(
-            Some(TaskKind::WalReceiverManager),
-            Some(self.tenant_shard_id),
-            Some(self.timeline_id),
-        )
-        .await;
+    #[instrument(skip_all, level = tracing::Level::DEBUG)]
+    pub fn cancel(&self) {
+        debug_assert_current_span_has_tenant_and_timeline_id();
+        debug!("cancelling walreceiver tasks");
+        self.cancel.cancel();
    }

    pub(crate) fn status(&self) -> Option<ConnectionManagerStatus> {
@@ -170,14 +159,18 @@ enum TaskStateUpdate<E> {

 impl<E: Clone> TaskHandle<E> {
    /// Initializes the task, starting it immediately after the creation.
+    ///
+    /// The second argument to `task` is a child token of `cancel_parent` ([`CancellationToken::child_token`]).
+    /// It being a child token enables us to provide a [`Self::shutdown`] method.
    fn spawn<Fut>(
+        cancel_parent: &CancellationToken,
        task: impl FnOnce(watch::Sender<TaskStateUpdate<E>>, CancellationToken) -> Fut + Send + 'static,
    ) -> Self
    where
        Fut: Future<Output = anyhow::Result<()>> + Send,
        E: Send + Sync + 'static,
    {
-        let cancellation = CancellationToken::new();
+        let cancellation = cancel_parent.child_token();
        let (events_sender, events_receiver) = watch::channel(TaskStateUpdate::Started);

        let cancellation_clone = cancellation.clone();
@@ -197,6 +190,9 @@ impl<E: Clone> TaskHandle<E> {
        }
    }

+    /// # Cancel-Safety
+    ///
+    /// Cancellation-safe.
    async fn next_task_event(&mut self) -> TaskEvent<E> {
        match self.events_receiver.changed().await {
            Ok(()) => TaskEvent::Update((self.events_receiver.borrow()).clone()),
@@ -17,7 +17,7 @@ use crate::metrics::{
    WALRECEIVER_ACTIVE_MANAGERS, WALRECEIVER_BROKER_UPDATES, WALRECEIVER_CANDIDATES_ADDED,
    WALRECEIVER_CANDIDATES_REMOVED, WALRECEIVER_SWITCHES,
 };
-use crate::task_mgr::{shutdown_token, TaskKind};
+use crate::task_mgr::TaskKind;
 use crate::tenant::{debug_assert_current_span_has_tenant_and_timeline_id, Timeline};
 use anyhow::Context;
 use chrono::{NaiveDateTime, Utc};
@@ -27,7 +27,7 @@ use storage_broker::proto::SafekeeperTimelineInfo;
 use storage_broker::proto::SubscribeSafekeeperInfoRequest;
 use storage_broker::proto::TenantTimelineId as ProtoTenantTimelineId;
 use storage_broker::{BrokerClientChannel, Code, Streaming};
-use tokio::select;
+use tokio_util::sync::CancellationToken;
 use tracing::*;

 use postgres_connection::PgConnectionConfig;
@@ -45,27 +45,33 @@ use super::{
    TaskEvent, TaskHandle,
 };

+pub(crate) struct Cancelled;
+
 /// Attempts to subscribe for timeline updates, pushed by safekeepers into the broker.
 /// Based on the updates, desides whether to start, keep or stop a WAL receiver task.
 /// If storage broker subscription is cancelled, exits.
+///
+/// # Cancel-Safety
+///
+/// Not cancellation-safe. Use `cancel` token to request cancellation.
 pub(super) async fn connection_manager_loop_step(
    broker_client: &mut BrokerClientChannel,
    connection_manager_state: &mut ConnectionManagerState,
    ctx: &RequestContext,
+    cancel: &CancellationToken,
    manager_status: &std::sync::RwLock<Option<ConnectionManagerStatus>>,
-) -> ControlFlow<(), ()> {
-    match connection_manager_state
-        .timeline
-        .wait_to_become_active(ctx)
-        .await
-    {
+) -> Result<(), Cancelled> {
+    match tokio::select! {
+        _ = cancel.cancelled() => { return Err(Cancelled); },
+        st = connection_manager_state.timeline.wait_to_become_active(ctx) => { st }
+    } {
        Ok(()) => {}
        Err(new_state) => {
            debug!(
                ?new_state,
                "state changed, stopping wal connection manager loop"
            );
-            return ControlFlow::Break(());
+            return Err(Cancelled);
        }
    }

@@ -86,7 +92,7 @@ pub(super) async fn connection_manager_loop_step(
    // Subscribe to the broker updates. Stream shares underlying TCP connection
    // with other streams on this client (other connection managers). When
    // object goes out of scope, stream finishes in drop() automatically.
-    let mut broker_subscription = subscribe_for_timeline_updates(broker_client, id).await;
+    let mut broker_subscription = subscribe_for_timeline_updates(broker_client, id, cancel).await?;
    debug!("Subscribed for broker timeline updates");

    loop {
@@ -94,6 +100,7 @@ pub(super) async fn connection_manager_loop_step(

        // These things are happening concurrently:
        //
+        // - cancellation request
        //  - keep receiving WAL on the current connection
        //      - if the shared state says we need to change connection, disconnect and return
        //      - this runs in a separate task and we receive updates via a watch channel
@@ -101,7 +108,11 @@ pub(super) async fn connection_manager_loop_step(
        //  - receive updates from broker
        //      - this might change the current desired connection
        //  - timeline state changes to something that does not allow walreceiver to run concurrently
-        select! {
+
+        // NB: make sure each of the select expressions are cancellation-safe
+        // (no need for arms to be cancellation-safe).
+        tokio::select! {
+            _ = cancel.cancelled() => { return Err(Cancelled); }
            Some(wal_connection_update) = async {
                match connection_manager_state.wal_connection.as_mut() {
                    Some(wal_connection) => Some(wal_connection.connection_task.next_task_event().await),
@@ -133,7 +144,7 @@ pub(super) async fn connection_manager_loop_step(
            },

            // Got a new update from the broker
-            broker_update = broker_subscription.message() => {
+            broker_update = broker_subscription.message() /* TODO: review cancellation-safety */ => {
                match broker_update {
                    Ok(Some(broker_update)) => connection_manager_state.register_timeline_update(broker_update),
                    Err(status) => {
@@ -147,16 +158,17 @@ pub(super) async fn connection_manager_loop_step(
                                warn!("broker subscription failed: {status}");
                            }
                        }
-                        return ControlFlow::Continue(());
+                        return Ok(());
                    }
                    Ok(None) => {
                        error!("broker subscription stream ended"); // can't happen
-                        return ControlFlow::Continue(());
+                        return Ok(());
                    }
                }
            },

            new_event = async {
+                // Reminder: this match arm needs to be cancellation-safe.
                loop {
                    if connection_manager_state.timeline.current_state() == TimelineState::Loading {
                        warn!("wal connection manager should only be launched after timeline has become active");
@@ -182,11 +194,11 @@ pub(super) async fn connection_manager_loop_step(
                }
            } => match new_event {
                ControlFlow::Continue(()) => {
-                    return ControlFlow::Continue(());
+                    return Ok(());
                }
                ControlFlow::Break(()) => {
                    debug!("Timeline is no longer active, stopping wal connection manager loop");
-                    return ControlFlow::Break(());
+                    return Err(Cancelled);
                }
            },

@@ -218,16 +230,15 @@ pub(super) async fn connection_manager_loop_step(
 async fn subscribe_for_timeline_updates(
    broker_client: &mut BrokerClientChannel,
    id: TenantTimelineId,
-) -> Streaming<SafekeeperTimelineInfo> {
+    cancel: &CancellationToken,
+) -> Result<Streaming<SafekeeperTimelineInfo>, Cancelled> {
    let mut attempt = 0;
-    let cancel = shutdown_token();
-
    loop {
        exponential_backoff(
            attempt,
            DEFAULT_BASE_BACKOFF_SECONDS,
            DEFAULT_MAX_BACKOFF_SECONDS,
-            &cancel,
+            cancel,
        )
        .await;
        attempt += 1;
@@ -241,9 +252,14 @@ async fn subscribe_for_timeline_updates(
            subscription_key: Some(key),
        };

-        match broker_client.subscribe_safekeeper_info(request).await {
+        match {
+            tokio::select! {
+                r = broker_client.subscribe_safekeeper_info(request) => { r }
+                _ = cancel.cancelled() => { return Err(Cancelled); }
+            }
+        } {
            Ok(resp) => {
-                return resp.into_inner();
+                return Ok(resp.into_inner());
            }
            Err(e) => {
                // Safekeeper nodes can stop pushing timeline updates to the broker, when no new writes happen and
@@ -264,6 +280,8 @@ pub(super) struct ConnectionManagerState {
    id: TenantTimelineId,
    /// Use pageserver data about the timeline to filter out some of the safekeepers.
    timeline: Arc<Timeline>,
+    /// Child token of [`super::WalReceiver::cancel`], inherited to all tasks we spawn.
+    cancel: CancellationToken,
    conf: WalReceiverConf,
    /// Current connection to safekeeper for WAL streaming.
    wal_connection: Option<WalConnection>,
@@ -386,7 +404,11 @@ struct BrokerSkTimeline {
 }

 impl ConnectionManagerState {
-    pub(super) fn new(timeline: Arc<Timeline>, conf: WalReceiverConf) -> Self {
+    pub(super) fn new(
+        timeline: Arc<Timeline>,
+        conf: WalReceiverConf,
+        cancel: CancellationToken,
+    ) -> Self {
        let id = TenantTimelineId {
            tenant_id: timeline.tenant_shard_id.tenant_id,
            timeline_id: timeline.timeline_id,
@@ -394,6 +416,7 @@ impl ConnectionManagerState {
        Self {
            id,
            timeline,
+            cancel,
            conf,
            wal_connection: None,
            wal_stream_candidates: HashMap::new(),
@@ -401,6 +424,22 @@ impl ConnectionManagerState {
        }
    }

+    fn spawn<Fut>(
+        &self,
+        task: impl FnOnce(
+                tokio::sync::watch::Sender<TaskStateUpdate<WalConnectionStatus>>,
+                CancellationToken,
+            ) -> Fut
+            + Send
+            + 'static,
+    ) -> TaskHandle<WalConnectionStatus>
+    where
+        Fut: std::future::Future<Output = anyhow::Result<()>> + Send,
+    {
+        // TODO: get rid of TaskHandle
+        super::TaskHandle::spawn(&self.cancel, task)
+    }
+
    /// Shuts down the current connection (if any) and immediately starts another one with the given connection string.
    async fn change_connection(&mut self, new_sk: NewWalConnectionCandidate, ctx: &RequestContext) {
        WALRECEIVER_SWITCHES
@@ -419,7 +458,7 @@ impl ConnectionManagerState {
        );

        let span = info_span!("connection", %node_id);
-        let connection_handle = TaskHandle::spawn(move |events_sender, cancellation| {
+        let connection_handle = self.spawn(move |events_sender, cancellation| {
            async move {
                debug_assert_current_span_has_tenant_and_timeline_id();

@@ -447,6 +486,12 @@ impl ConnectionManagerState {
                                info!("walreceiver connection handling ended: {e}");
                                Ok(())
                            }
+                            WalReceiverError::ClosedGate => {
+                                info!(
+                                    "walreceiver connection handling ended because of closed gate"
+                                );
+                                Ok(())
+                            }
                            WalReceiverError::Other(e) => {
                                // give out an error to have task_mgr give it a really verbose logging
                                if cancellation.is_cancelled() {
@@ -486,6 +531,10 @@ impl ConnectionManagerState {

    /// Drops the current connection (if any) and updates retry timeout for the next
    /// connection attempt to the same safekeeper.
+    ///
+    /// # Cancel-Safety
+    ///
+    /// Not cancellation-safe.
    async fn drop_old_connection(&mut self, needs_shutdown: bool) {
        let wal_connection = match self.wal_connection.take() {
            Some(wal_connection) => wal_connection,
@@ -493,7 +542,14 @@ impl ConnectionManagerState {
        };

        if needs_shutdown {
-            wal_connection.connection_task.shutdown().await;
+            wal_connection
+                .connection_task
+                .shutdown()
+                // This here is why this function isn't cancellation-safe.
+                // If we got cancelled here, then self.wal_connection is already None and we lose track of the task.
+                // Even if our caller diligently calls Self::shutdown(), it will find a self.wal_connection=None
+                // and thus be ineffective.
+                .await;
        }

        let retry = self
@@ -838,6 +894,9 @@ impl ConnectionManagerState {
        }
    }

+    /// # Cancel-Safety
+    ///
+    /// Not cancellation-safe.
    pub(super) async fn shutdown(mut self) {
        if let Some(wal_connection) = self.wal_connection.take() {
            wal_connection.connection_task.shutdown().await;
@@ -986,7 +1045,7 @@ mod tests {
            sk_id: connected_sk_id,
            availability_zone: None,
            status: connection_status,
-            connection_task: TaskHandle::spawn(move |sender, _| async move {
+            connection_task: state.spawn(move |sender, _| async move {
                sender
                    .send(TaskStateUpdate::Progress(connection_status))
                    .ok();
@@ -1154,7 +1213,7 @@ mod tests {
            sk_id: connected_sk_id,
            availability_zone: None,
            status: connection_status,
-            connection_task: TaskHandle::spawn(move |sender, _| async move {
+            connection_task: state.spawn(move |sender, _| async move {
                sender
                    .send(TaskStateUpdate::Progress(connection_status))
                    .ok();
@@ -1221,7 +1280,7 @@ mod tests {
            sk_id: NodeId(1),
            availability_zone: None,
            status: connection_status,
-            connection_task: TaskHandle::spawn(move |sender, _| async move {
+            connection_task: state.spawn(move |sender, _| async move {
                sender
                    .send(TaskStateUpdate::Progress(connection_status))
                    .ok();
@@ -1285,7 +1344,7 @@ mod tests {
            sk_id: NodeId(1),
            availability_zone: None,
            status: connection_status,
-            connection_task: TaskHandle::spawn(move |_, _| async move { Ok(()) }),
+            connection_task: state.spawn(move |_, _| async move { Ok(()) }),
            discovered_new_wal: Some(NewCommittedWAL {
                discovered_at: time_over_threshold,
                lsn: new_lsn,
@@ -1341,6 +1400,7 @@ mod tests {
                timeline_id: TIMELINE_ID,
            },
            timeline,
+            cancel: CancellationToken::new(),
            conf: WalReceiverConf {
                wal_connect_timeout: Duration::from_secs(1),
                lagging_wal_timeout: Duration::from_secs(1),
@@ -1384,7 +1444,7 @@ mod tests {
            sk_id: connected_sk_id,
            availability_zone: None,
            status: connection_status,
-            connection_task: TaskHandle::spawn(move |sender, _| async move {
+            connection_task: state.spawn(move |sender, _| async move {
                sender
                    .send(TaskStateUpdate::Progress(connection_status))
                    .ok();
@@ -27,7 +27,6 @@ use super::TaskStateUpdate;
 use crate::{
    context::RequestContext,
    metrics::{LIVE_CONNECTIONS_COUNT, WALRECEIVER_STARTED_CONNECTIONS, WAL_INGEST},
-    task_mgr,
    task_mgr::TaskKind,
    task_mgr::WALRECEIVER_RUNTIME,
    tenant::{debug_assert_current_span_has_tenant_and_timeline_id, Timeline, WalReceiverInfo},
@@ -37,8 +36,8 @@ use crate::{
 use postgres_backend::is_expected_io_error;
 use postgres_connection::PgConnectionConfig;
 use postgres_ffi::waldecoder::WalStreamDecoder;
-use utils::pageserver_feedback::PageserverFeedback;
 use utils::{id::NodeId, lsn::Lsn};
+use utils::{pageserver_feedback::PageserverFeedback, sync::gate::GateError};

 /// Status of the connection.
 #[derive(Debug, Clone, Copy)]
@@ -68,6 +67,7 @@ pub(super) enum WalReceiverError {
    SuccessfulCompletion(String),
    /// Generic error
    Other(anyhow::Error),
+    ClosedGate,
 }

 impl From<tokio_postgres::Error> for WalReceiverError {
@@ -119,6 +119,16 @@ pub(super) async fn handle_walreceiver_connection(
 ) -> Result<(), WalReceiverError> {
    debug_assert_current_span_has_tenant_and_timeline_id();

+    // prevent timeline shutdown from finishing until we have exited
+    let _guard = timeline.gate.enter().map_err(|e| match e {
+        GateError::GateClosed => WalReceiverError::ClosedGate,
+    })?;
+    // This function spawns a side-car task (WalReceiverConnectionPoller).
+    // Get its gate guard now as well.
+    let poller_guard = timeline.gate.enter().map_err(|e| match e {
+        GateError::GateClosed => WalReceiverError::ClosedGate,
+    })?;
+
    WALRECEIVER_STARTED_CONNECTIONS.inc();

    // Connect to the database in replication mode.
@@ -156,22 +166,19 @@ pub(super) async fn handle_walreceiver_connection(
    }

    // The connection object performs the actual communication with the database,
-    // so spawn it off to run on its own.
+    // so spawn it off to run on its own. It shouldn't outlive this function, but,
+    // due to lack of async drop, we can't enforce that. However, we ensure that
+    // 1. it is sensitive to `cancellation` and
+    // 2. holds the Timeline gate open so that after timeline shutdown,
+    //    we know this task is gone.
    let _connection_ctx = ctx.detached_child(
        TaskKind::WalReceiverConnectionPoller,
        ctx.download_behavior(),
    );
    let connection_cancellation = cancellation.clone();
-    task_mgr::spawn(
-        WALRECEIVER_RUNTIME.handle(),
-        TaskKind::WalReceiverConnectionPoller,
-        Some(timeline.tenant_shard_id),
-        Some(timeline.timeline_id),
-        "walreceiver connection",
-        false,
+    WALRECEIVER_RUNTIME.spawn(
        async move {
            debug_assert_current_span_has_tenant_and_timeline_id();
-
            select! {
                connection_result = connection => match connection_result {
                    Ok(()) => debug!("Walreceiver db connection closed"),
@@ -182,6 +189,9 @@ pub(super) async fn handle_walreceiver_connection(
                                // with a similar error.
                            },
                            WalReceiverError::SuccessfulCompletion(_) => {}
+                            WalReceiverError::ClosedGate => {
+                                // doesn't happen at runtime
+                            }
                            WalReceiverError::Other(err) => {
                                warn!("Connection aborted: {err:#}")
                            }
@@ -190,7 +200,7 @@ pub(super) async fn handle_walreceiver_connection(
                },
                _ = connection_cancellation.cancelled() => debug!("Connection cancelled"),
            }
-            Ok(())
+            drop(poller_guard);
        }
        // Enrich the log lines emitted by this closure with meaningful context.
        // TODO: technically, this task outlives the surrounding function, so, the
@@ -303,6 +313,7 @@ pub(super) async fn handle_walreceiver_connection(

                trace!("received XLogData between {startlsn} and {endlsn}");

+                WAL_INGEST.bytes_received.inc_by(data.len() as u64);
                waldecoder.feed_bytes(data);

                {
@@ -389,17 +400,6 @@ pub(super) async fn handle_walreceiver_connection(
            }
        }

-        {
-            // This is a hack. It piggybacks on the keepalive messages sent by the
-            // safekeeper in order to enforce `checkpoint_timeout` on the currently
-            // open layer. This hack doesn't provide a bound on the total size of
-            // in-memory layers on a pageserver. See https://github.com/neondatabase/neon/issues/6916.
-            let mut writer = timeline.writer().await;
-            if let Err(err) = writer.tick().await {
-                warn!("Timeline writer tick failed: {err}");
-            }
-        }
-
        if let Some(last_lsn) = status_update {
            let timeline_remote_consistent_lsn = timeline
                .get_remote_consistent_lsn_visible()
@@ -121,11 +121,16 @@ pub(super) enum SetDeletedFlagProgress {
    Successful(NaiveDateTime),
 }

-pub(super) struct UploadQueueStopped {
+pub(super) struct UploadQueueStoppedDeletable {
    pub(super) upload_queue_for_deletion: UploadQueueInitialized,
    pub(super) deleted_at: SetDeletedFlagProgress,
 }

+pub(super) enum UploadQueueStopped {
+    Deletable(UploadQueueStoppedDeletable),
+    Uninitialized,
+}
+
 #[derive(thiserror::Error, Debug)]
 pub(crate) enum NotInitialized {
    #[error("queue is in state Uninitialized")]
@@ -249,12 +254,15 @@ impl UploadQueue {
        }
    }

-    pub(crate) fn stopped_mut(&mut self) -> anyhow::Result<&mut UploadQueueStopped> {
+    pub(crate) fn stopped_mut(&mut self) -> anyhow::Result<&mut UploadQueueStoppedDeletable> {
        match self {
            UploadQueue::Initialized(_) | UploadQueue::Uninitialized => {
                anyhow::bail!("queue is in state {}", self.as_str())
            }
-            UploadQueue::Stopped(stopped) => Ok(stopped),
+            UploadQueue::Stopped(UploadQueueStopped::Uninitialized) => {
+                anyhow::bail!("queue is in state Stopped(Uninitialized)")
+            }
+            UploadQueue::Stopped(UploadQueueStopped::Deletable(deletable)) => Ok(deletable),
        }
    }
 }
@@ -61,7 +61,7 @@ pub struct VectoredRead {
 }

 impl VectoredRead {
-    fn size(&self) -> usize {
+    pub fn size(&self) -> usize {
        (self.end - self.start) as usize
    }
 }
@@ -15,11 +15,23 @@ pub(crate) fn regenerate(tenants_path: &Path) -> anyhow::Result<PageserverUtiliz
        .map_err(std::io::Error::from)
        .context("statvfs tenants directory")?;

-    let blocksz = statvfs.block_size();
+    // https://unix.stackexchange.com/a/703650
+    let blocksz = if statvfs.fragment_size() > 0 {
+        statvfs.fragment_size()
+    } else {
+        statvfs.block_size()
+    };

    #[cfg_attr(not(target_os = "macos"), allow(clippy::unnecessary_cast))]
    let free = statvfs.blocks_available() as u64 * blocksz;
-    let used = crate::metrics::RESIDENT_PHYSICAL_SIZE_GLOBAL.get();
+
+    #[cfg_attr(not(target_os = "macos"), allow(clippy::unnecessary_cast))]
+    let used = statvfs
+        .blocks()
+        // use blocks_free instead of available here to match df in case someone compares
+        .saturating_sub(statvfs.blocks_free()) as u64
+        * blocksz;
+
    let captured_at = std::time::SystemTime::now();

    let doc = PageserverUtilization {
@@ -782,7 +782,7 @@ where
        }
    }
    // NB: don't use `buf.is_empty()` here; it is from the
-    // `impl Deref for Slice { Target = [u8] }`; the the &[u8]
+    // `impl Deref for Slice { Target = [u8] }`; the &[u8]
    // returned by it only covers the initialized portion of `buf`.
    // Whereas we're interested in ensuring that we filled the entire
    // buffer that the user passed in.
@@ -36,11 +36,12 @@ use bytes::{Bytes, BytesMut};
 use pageserver_api::key::key_to_rel_block;
 use pageserver_api::models::WalRedoManagerStatus;
 use pageserver_api::shard::TenantShardId;
-use std::sync::{Arc, RwLock};
+use std::sync::Arc;
 use std::time::Duration;
 use std::time::Instant;
 use tracing::*;
 use utils::lsn::Lsn;
+use utils::sync::heavier_once_cell;

 ///
 /// This is the real implementation that uses a Postgres process to
@@ -53,7 +54,19 @@ pub struct PostgresRedoManager {
    tenant_shard_id: TenantShardId,
    conf: &'static PageServerConf,
    last_redo_at: std::sync::Mutex<Option<Instant>>,
-    redo_process: RwLock<Option<Arc<process::WalRedoProcess>>>,
+    /// 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
+    /// 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,
+    /// it can take it out of rotation (= using [`heavier_once_cell::Guard::take_and_deinit`].
+    /// and retry redo, thereby starting the new process, while other redo tasks might
+    /// 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>>,
 }

 ///
@@ -101,6 +114,7 @@ impl PostgresRedoManager {
                        self.conf.wal_redo_timeout,
                        pg_version,
                    )
+                    .await
                };
                img = Some(result?);

@@ -121,6 +135,7 @@ impl PostgresRedoManager {
                self.conf.wal_redo_timeout,
                pg_version,
            )
+            .await
        }
    }

@@ -134,7 +149,7 @@ impl PostgresRedoManager {
                    chrono::Utc::now().checked_sub_signed(chrono::Duration::from_std(age).ok()?)
                })
            },
-            pid: self.redo_process.read().unwrap().as_ref().map(|p| p.id()),
+            pid: self.redo_process.get().map(|p| p.id()),
        })
    }
 }
@@ -152,7 +167,7 @@ impl PostgresRedoManager {
            tenant_shard_id,
            conf,
            last_redo_at: std::sync::Mutex::default(),
-            redo_process: RwLock::new(None),
+            redo_process: heavier_once_cell::OnceCell::default(),
        }
    }

@@ -164,8 +179,7 @@ impl PostgresRedoManager {
            if let Some(last_redo_at) = *g {
                if last_redo_at.elapsed() >= idle_timeout {
                    drop(g);
-                    let mut guard = self.redo_process.write().unwrap();
-                    *guard = None;
+                    drop(self.redo_process.get().map(|guard| guard.take_and_deinit()));
                }
            }
        }
@@ -174,8 +188,11 @@ impl PostgresRedoManager {
    ///
    /// Process one request for WAL redo using wal-redo postgres
    ///
+    /// # Cancel-Safety
+    ///
+    /// Cancellation safe.
    #[allow(clippy::too_many_arguments)]
-    fn apply_batch_postgres(
+    async fn apply_batch_postgres(
        &self,
        key: Key,
        lsn: Lsn,
@@ -191,42 +208,31 @@ impl PostgresRedoManager {
        const MAX_RETRY_ATTEMPTS: u32 = 1;
        let mut n_attempts = 0u32;
        loop {
-            // launch the WAL redo process on first use
-            let proc: Arc<process::WalRedoProcess> = {
-                let proc_guard = self.redo_process.read().unwrap();
-                match &*proc_guard {
-                    None => {
-                        // "upgrade" to write lock to launch the process
-                        drop(proc_guard);
-                        let mut proc_guard = self.redo_process.write().unwrap();
-                        match &*proc_guard {
-                            None => {
-                                let start = Instant::now();
-                                let proc = Arc::new(
-                                    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"
-                                );
-                                *proc_guard = Some(Arc::clone(&proc));
-                                proc
-                            }
-                            Some(proc) => Arc::clone(proc),
-                        }
+            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(
+                                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
                    }
-                    Some(proc) => Arc::clone(proc),
-                }
-            };
+                };

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

@@ -272,34 +278,34 @@ impl PostgresRedoManager {
                    n_attempts,
                    e,
                );
-                // Avoid concurrent callers hitting the same issue.
-                // We can't prevent it from happening because we want to enable parallelism.
-                {
-                    let mut guard = self.redo_process.write().unwrap();
-                    match &*guard {
-                        Some(current_field_value) => {
-                            if Arc::ptr_eq(current_field_value, &proc) {
-                                // We're the first to observe an error from `proc`, it's our job to take it out of rotation.
-                                *guard = None;
-                            }
-                        }
-                        None => {
-                            // Another thread was faster to observe the error, and already took the process out of rotation.
-                        }
-                    }
-                }
+                // Avoid concurrent callers hitting the same issue by taking `proc` out of the rotation.
+                // Note that there may be other tasks concurrent with us that also hold `proc`.
+                // We have to deal with that here.
+                // Also read the doc comment on field `self.redo_process`.
+                //
                // NB: there may still be other concurrent threads using `proc`.
                // The last one will send SIGKILL when the underlying Arc reaches refcount 0.
-                // NB: it's important to drop(proc) after drop(guard). Otherwise we'd keep
-                // holding the lock while waiting for the process to exit.
-                // NB: the drop impl blocks the current threads with a wait() system call for
-                // the child process. We dropped the `guard` above so that other threads aren't
-                // affected. But, it's good that the current thread _does_ block to wait.
-                // If we instead deferred the waiting into the background / to tokio, it could
-                // happen that if walredo always fails immediately, we spawn processes faster
+                //
+                // NB: the drop impl blocks the dropping thread with a wait() system call for
+                // the child process. In some ways the blocking is actually good: if we
+                // deferred the waiting into the background / to tokio if we used `tokio::process`,
+                // it could happen that if walredo always fails immediately, we spawn processes faster
                // than we can SIGKILL & `wait` for them to exit. By doing it the way we do here,
                // we limit this risk of run-away to at most $num_runtimes * $num_executor_threads.
                // This probably needs revisiting at some later point.
+                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.
+                        }
+                    }
+                }
+                // The last task that does this `drop()` of `proc` will do a blocking `wait()` syscall.
                drop(proc);
            } else if n_attempts != 0 {
                info!(n_attempts, "retried walredo succeeded");
@@ -111,6 +111,7 @@ static PageServer page_servers[MAX_SHARDS];

 static bool pageserver_flush(shardno_t shard_no);
 static void pageserver_disconnect(shardno_t shard_no);
+static void pageserver_disconnect_shard(shardno_t shard_no);

 static bool
 PagestoreShmemIsValid(void)
@@ -487,9 +488,32 @@ retry:
 	return ret;
 }

-
+/*
+ * Reset prefetch and drop connection to the shard.
+ * It also drops connection to all other shards involved in prefetch.
+ */
 static void
 pageserver_disconnect(shardno_t shard_no)
+{
+	/*
+	 * If the connection to any pageserver is lost, we throw away the
+	 * whole prefetch queue, even for other pageservers. It should not
+	 * cause big problems, because connection loss is supposed to be a
+	 * rare event.
+	 *
+	 * Prefetch state should be reset even if page_servers[shard_no].conn == NULL,
+	 * because prefetch request may be registered before connection is established.
+	 */
+	prefetch_on_ps_disconnect();
+
+	pageserver_disconnect_shard(shard_no);
+}
+
+/*
+ * Disconnect from specified shard
+ */
+static void
+pageserver_disconnect_shard(shardno_t shard_no)
 {
 	/*
 	 * If anything goes wrong while we were sending a request, it's not clear
@@ -503,14 +527,6 @@ pageserver_disconnect(shardno_t shard_no)
 		neon_shard_log(shard_no, LOG, "dropping connection to page server due to error");
 		PQfinish(page_servers[shard_no].conn);
 		page_servers[shard_no].conn = NULL;
-
-		/*
-		 * If the connection to any pageserver is lost, we throw away the
-		 * whole prefetch queue, even for other pageservers. It should not
-		 * cause big problems, because connection loss is supposed to be a
-		 * rare event.
-		 */
-		prefetch_on_ps_disconnect();
 	}
 	if (page_servers[shard_no].wes != NULL)
 	{
@@ -676,7 +692,8 @@ page_server_api api =
 {
 	.send = pageserver_send,
 	.flush = pageserver_flush,
-	.receive = pageserver_receive
+	.receive = pageserver_receive,
+	.disconnect = pageserver_disconnect_shard
 };

 static bool
@@ -312,7 +312,7 @@ pg_cluster_size(PG_FUNCTION_ARGS)
 {
 	int64		size;

-	size = GetZenithCurrentClusterSize();
+	size = GetNeonCurrentClusterSize();

 	if (size == 0)
 		PG_RETURN_NULL();
--- a/Show More
+++ b/Show More