Add storage.wal.failover.write_and_sync.latency
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Fixes DOC-13184 Summary of changes: - Add a mention of the `storage.wal.failover.write_and_sync.latency` metric to the `wal-failover-metrics.md` include file, which will pull it into the 'WAL failover' and 'cockroach start' pages. - We're also doing a cockroachdb/cockroach PR to mark this metric as 'essential', so it shows up in the list of Storage essential metrics at e.g. https://www.cockroachlabs.com/docs/v25.3/essential-metrics-self-hosted.html#storage
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rmloveland
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Oct 14, 2025
This change marks the `storage.wal.failover.write_and_sync.latency` metric as "Essential" so it gets automatically pulled into the 'Essential Metrics' documentation at e.g., https://www.cockroachlabs.com/docs/stable/essential-metrics-self-hosted.html#storage This is necessary since we are adding some words about this metric to the docs via cockroachdb/docs#20566 We would like to then backport this change to all supported versions of CockroachDB which have WAL failover (i.e., v24.1 and later).
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sumeerbhola
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Oct 15, 2025
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src/current/_includes/v25.4/wal-failover-metrics.md line 7 at r1 (raw file):
- `storage.wal.failover.switch.count`: Count of the number of times WAL writing has switched from primary to secondary store, and vice versa. - `storage.wal.fsync.latency` monitors the latencies of WAL files. If you have WAL failover enabled and are failing over, `storage.wal.fsync.latency` will include the latency of the stalled primary. - `storage.wal.failover.write_and_sync.latency` metric is up one level from `storage.wal.fsync.latency`, and during the failover will report the latency actually observed by higher levels (which should be ~equivalent to the latency of the secondary).
It is not just during the failover. We should say something like.
When WAL failover is configured in a cluster, the operator should monitor this metric which shows the effective latency observed by the higher layer writing to the WAL. This metric is expected to stay low in a healthy system, regardless of whether WAL files are being written to the primary or secondary.
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thanks @sumeerbhola, i've updated in 998c744 - PTAL once we're happy with this change and it's had docs review I would like to backport it to the WAL failover docs for all versions where this metric is supported which previous versions have this metric available? is it everything v24.1+ or only a subset? |
craig bot
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Oct 15, 2025
155395: storage: mark add'l WAL latency metric essential r=rmloveland a=rmloveland This change marks the `storage.wal.failover.write_and_sync.latency` metric as "Essential" so it gets automatically pulled into the 'Essential Metrics' documentation at e.g., https://www.cockroachlabs.com/docs/stable/essential-metrics-self-hosted.html#storage This is necessary since we are adding some words about this metric to the docs via cockroachdb/docs#20566 We would like to then backport this change to all supported versions of CockroachDB which have WAL failover (i.e., v24.1 and later). Addresses part of DOC-13184 Co-authored-by: Rich Loveland <[email protected]>
rmloveland
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Oct 16, 2025
This change marks the `storage.wal.failover.write_and_sync.latency` metric as "Essential" so it gets automatically pulled into the 'Essential Metrics' documentation at e.g., https://www.cockroachlabs.com/docs/stable/essential-metrics-self-hosted.html#storage This is necessary since we are adding some words about this metric to the docs via cockroachdb/docs#20566 We would like to then backport this change to all supported versions of CockroachDB which have WAL failover (i.e., v24.1 and later).
rmloveland
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Oct 16, 2025
This change marks the `storage.wal.failover.write_and_sync.latency` metric as "Essential" so it gets automatically pulled into the 'Essential Metrics' documentation at e.g., https://www.cockroachlabs.com/docs/stable/essential-metrics-self-hosted.html#storage This is necessary since we are adding some words about this metric to the docs via cockroachdb/docs#20566 We would like to then backport this change to all supported versions of CockroachDB which have WAL failover (i.e., v24.1 and later).
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Fixes DOC-13184
Summary of changes:
Add a mention of the
storage.wal.failover.write_and_sync.latencymetric to thewal-failover-metrics.mdinclude file, which will pull it into the 'WAL failover' and 'cockroach start' pages.We're also doing storage: mark add'l WAL latency metric essential cockroach#155395 to mark this metric as 'essential', so it shows up in the list of Storage essential metrics at e.g. https://www.cockroachlabs.com/docs/v25.3/essential-metrics-self-hosted.html#storage