windows_exporter/docs/runbooks/windowsdiskwritelatencyhigh.md

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WindowsDiskWriteLatencyHigh

Meaning

Average disk write service time exceeds the configured threshold for 15 minutes. The default is 0.05 seconds (50 ms) per operation, computed from write-time and write-operation counter rates. Volumes with no writes produce no latency sample.

Impact

Slow writes may delay transactions, log flushing, file uploads, or paging. An average can conceal short periods of very high latency.

Diagnosis

1. Inspect windows:logical_disk_write_latency:seconds, write IOPS, write throughput, windows:logical_disk_busy:ratio, and queued requests for the affected volume.
2. Use Resource Monitor to find processes generating writes. Review backup jobs, database checkpoints, log growth, and scheduled maintenance.
3. Check free space and storage-controller health. Inspect System event logs for disk, controller, multipath, or network-storage errors.
4. For virtual machines or remote storage, inspect the backing datastore and array for throughput limits and contention.

Mitigation

Reduce competing writes or move maintenance jobs. Repair storage-path problems and expand IOPS or throughput capacity. Coordinate database or logging changes with the application owner. Avoid disabling durability guarantees to silence an alert. Confirm application write latency recovers and the disk metrics improve.