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docs(immich): cap server-side job concurrency to protect sdc + log recurrence

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A library-wide Duplicate Detection run on 2026-06-01 fanned the ML/thumbnail
backfill out at thumbnailGeneration concurrency 8, saturating the shared sdc
HDD and starving etcd -> kube-apiserver down ~30 min (5th IO-pressure incident
on sdc). Capped server-side thumbnailGeneration/metadataExtraction/library to 2
in the Immich DB system-config; documented in the Immich row and recorded the
recurrence + still-TODO IO-isolation fixes in the 2026-05-25 post-mortem (this
also commits that previously-untracked post-mortem).

[ci skip]

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
This commit is contained in:
Viktor Barzin 2026-06-01 12:33:17 +00:00
parent af4bfbe046
commit 0dd4a31eff
2 changed files with 199 additions and 1 deletions
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@ -134,7 +134,7 @@ Repo IDs: infra=1, Website=2, finance=3, health=4, travel_blog=5, webhook-handle
| Service | Key Operational Knowledge |
|---------|--------------------------|
| Nextcloud | MaxRequestWorkers=150, needs 8Gi limit (Apache transient memory spikes, see commit eb94144), very generous startup probe |
| Immich | ML on SSD (CUDA), disable ModSecurity (breaks streaming), frequent upgrades. **Video transcoding is GPU-accelerated**: `immich-server` is pinned to GPU node1 (nodeSelector `nvidia.com/gpu.present` + NoSchedule toleration + `gpu-workload` priority) with a time-sliced `nvidia.com/gpu=1` slice — the stock immich-server image's ffmpeg already ships h264/hevc_nvenc + NVDEC. Activated via `ffmpeg.accel=nvenc` + `accelDecode=true` in the **DB** system-config (`system_metadata` table, key `system-config`, JSONB — NOT Terraform; app config is DB-managed here like oauth/smtp). Direct DB edits need a pod **recreate** to reload (config is cached at boot; only API-driven changes broadcast a reload). If Immich is ever reinstalled fresh (not restored), re-set these two keys. Thumbnails/previews live on SSD NFS (sdb) — do NOT move to block storage (HDD sdc = slower + the contended IO domain). |
| Immich | ML on SSD (CUDA), disable ModSecurity (breaks streaming), frequent upgrades. **Video transcoding is GPU-accelerated**: `immich-server` is pinned to GPU node1 (nodeSelector `nvidia.com/gpu.present` + NoSchedule toleration + `gpu-workload` priority) with a time-sliced `nvidia.com/gpu=1` slice — the stock immich-server image's ffmpeg already ships h264/hevc_nvenc + NVDEC. Activated via `ffmpeg.accel=nvenc` + `accelDecode=true` in the **DB** system-config (`system_metadata` table, key `system-config`, JSONB — NOT Terraform; app config is DB-managed here like oauth/smtp). Direct DB edits need a pod **recreate** to reload (config is cached at boot; only API-driven changes broadcast a reload). If Immich is ever reinstalled fresh (not restored), re-set these two keys. Thumbnails/previews live on SSD NFS (sdb) — do NOT move to block storage (HDD sdc = slower + the contended IO domain). **Background-job concurrency is capped to protect sdc** (DB-managed system-config, `system_metadata` key `system-config`, JSONB `job.*.concurrency`; re-set on fresh install): `thumbnailGeneration=2`, `metadataExtraction=2`, `library=2` — these jobs read ORIGINALS off the HDD library. Left uncapped (were 8/4/4) a library-wide job (e.g. Duplicate Detection on 2026-06-01) fans the ML/thumbnail backfill out into a read storm that saturates sdc and starves etcd → apiserver down. `sidecar`/`smartSearch`/`faceDetection` stay at Immich defaults (small `.xmp` / SSD previews). Apply via Job Settings UI or the `system-config` API; **direct DB edits need an `immich-server` pod recreate to reload** (config cached at boot). See `docs/post-mortems/2026-05-25-immich-anca-elements-io-storm.md`. |
| CrowdSec | Pin version, disable Metabase when not needed (CPU hog), LAPI scaled to 3, **DB on PostgreSQL** (migrated from MySQL), flush config: max_items=10000/max_age=7d/agents_autodelete=30d, DECISION_DURATION=168h in blocklist CronJob |
| Frigate | GPU stall detection in liveness probe (inference speed check), high CPU |
| Authentik | 3 replicas, PgBouncer in front of PostgreSQL, strip auth headers before forwarding |