feat: optional dedicated WAL volume for dataservers - #13
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Add server.wal.{storage,storageClassName} to give the WAL its own
volumeClaimTemplate, mounted at the configured storage.wal.dir
(default /data/wal), so WAL fsyncs don't compete with database I/O
for the same disk — and on cloud block storage each volume brings its
own IOPS budget. The WAL claim inherits server.storageClassName unless
its own storageClassName is set (e.g. a faster class just for the WAL).
When server.wal is unset the chart renders exactly as before (single
data volume), so existing installs are unaffected. Chart 0.0.8.
Signed-off-by: Matteo Merli <mmerli@apache.org>
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Adds
server.wal.storage(and optionalserver.wal.storageClassName) to the oxia-cluster chart: when set, dataservers get a secondvolumeClaimTemplatenamedwal, mounted at the configuredserver.config.storage.wal.dir(default/data/wal).Why: separating the WAL from the database puts fsync-latency-critical writes on their own device — WAL appends stop competing with pebble compaction/read I/O, and on cloud block storage (e.g. EBS gp3) each volume brings its own IOPS/throughput budget. The
storageClassNameoverride also allows a faster class just for the WAL. This mirrors the standard deployment practice for ZooKeeper (dataLogDir) and etcd (--wal-dir).Compatibility:
server.walunset renders byte-identical to 0.0.7 (singledatavolume) — existing installs unaffected. The WAL claim inheritsserver.storageClassNameunless its own class is set. Mounting at the configured wal dir means the dataserver config needs no change.Chart version bumped to 0.0.8.
Verification
helm lintclean;helm templatechecked in three modes:dataclaim, no wal mount (unchanged)--set server.wal.storage=10Gi --set server.storageClassName=gp3→walclaim (10Gi, gp3) mounted at/data/wal--set server.wal.storageClassName=io2→ wal claim on io2 while data stays on gp3