infra/stacks/dbaas
Viktor Barzin a2c8f906ec
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dbaas: stretch CNPG checkpoint timer 5->15min + raise WAL size (cut sdc write IOPS)
Viktor asked to reduce CNPG checkpoint/WAL writes as part of the sdc
IOPS-isolation work (code-oflt). The IOPS deep-dive found CNPG checkpoints
fire 100% on the 5-min timer (checkpoints_timed >> checkpoints_req), each
triggering a full-page-write burst + flush onto the contended 7200rpm sdc
spindle -- a top write-IOPS source after etcd.

Set checkpoint_timeout=15min + max_wal_size=4GB + min_wal_size=1GB so
checkpoints fire ~1/3 as often (fewer FPW) and WAL segments are recycled
rather than churned. All three are sighup-reloadable -> CNPG applies them
without a restart or failover. checkpoint_completion_target stays 0.9 so
each checkpoint's IO is still smeared across the interval. Bounded
recovery-time tradeoff (more WAL to replay on crash), acceptable for the
write relief. wal_compression left at pglz ('on') pending image
zstd-support verification.

Also refreshes the stale CNPG tuning note in .claude/CLAUDE.md (it listed
shared_buffers=512MB / effective_cache_size=1536MB / 2Gi; live is 1024MB /
2560MB / 3Gi).

Refs: code-oflt (etcd/sdc IO isolation).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
2026-06-29 11:41:09 +00:00
..
modules/dbaas dbaas: stretch CNPG checkpoint timer 5->15min + raise WAL size (cut sdc write IOPS) 2026-06-29 11:41:09 +00:00
main.tf fix: restore tree dropped by 6d224861; land stem95su gdrive-sync (10m) [ci skip] 2026-06-09 08:45:33 +00:00
secrets fix: restore tree dropped by 6d224861; land stem95su gdrive-sync (10m) [ci skip] 2026-06-09 08:45:33 +00:00
terragrunt.hcl fix: restore tree dropped by 6d224861; land stem95su gdrive-sync (10m) [ci skip] 2026-06-09 08:45:33 +00:00