kubernetes/apps/home-assistant/ha-pg-cluster.yaml

@@ -31,6 +31,11 @@ metadata:
   namespace: home-assistant
 spec:
   instances: 2
+  # switchover, not CNPG's default `restart`: any change that rolls the pods
+  # (walStorage below did) then promotes the already-rolled replica instead of
+  # restarting the primary in place, so the recorder loses seconds of writes
+  # rather than stopDelay plus a pg_wal move plus startup (REN-176).
+  primaryUpdateMethod: switchover
   smartShutdownTimeout: 10
   stopDelay: 60
   imageName: ghcr.io/cloudnative-pg/postgresql:16
@@ -61,7 +66,35 @@ spec:
     # one stalled night survives and two fill the volume; ~18.6 GiB carries
     # about four. Approved by the owner on REN-135.
     # ceph-block has allowVolumeExpansion: true, so this grows in place.
+    #
+    # Since REN-176 WAL lives on walStorage below, so the stall headroom above
+    # now belongs to that volume. 32Gi stays because a PVC cannot shrink.
     size: 32Gi
+  # WAL on its own volume (ha-pg-N-wal), approved by the owner on REN-176.
+  #
+  # PERMANENT. The CNPG webhook rejects removing walStorage once set ("walStorage
+  # cannot be disabled once configured"), so reverting this block fails
+  # admission and leaves the home-assistant Kustomization stuck. Undoing it
+  # means a new Cluster recovered from ha-pg-store. Adding it on 1.30.1 needs
+  # no re-clone: the operator creates the PVC, rolls each pod, and the instance
+  # manager moves pg_wal onto it before Postgres starts.
+  #
+  # This does NOT keep the recorder up when WAL fills: a full WAL disk still
+  # stops Postgres. What it does is keep WAL writable if PGDATA fills (a purge
+  # that stops running), and make WAL-volume usage a direct archiver-backlog
+  # signal.
+  #
+  # Sized so stall survival is no worse than the shared 32Gi gives today.
+  # Today: ~18.6 GiB free on PGDATA / 4.66 GiB/day of WAL = ~4.0 days.
+  #   1.86 GiB  normal pg_wal footprint (max_wal_size 2GB)
+  # + 18.64 GiB four days of full archiver outage at 4.66 GiB/day
+  #             (the nightly 56-119 segment burst, REN-136, is inside that rate)
+  # = 20.5 GiB -> 21Gi: (21 - 1.86) / 4.66 = ~4.1 days. 18Gi would give ~3.5,
+  # worse than today. RBD is thin, so the ceiling costs nothing until a stall
+  # fills it. The webhook requires min_wal_size < max_wal_size < this size.
+  walStorage:
+    storageClass: ceph-block
+    size: 21Gi
   plugins:
     - name: barman-cloud.cloudnative-pg.io
       isWALArchiver: true