EtcdHighCommitDurations

EtcdHighCommitDurations #

Etcd commit duration increasing, 99th percentile is over 0.25s

Alert Rule
alert: EtcdHighCommitDurations
annotations:
  description: |-
    Etcd commit duration increasing, 99th percentile is over 0.25s
      VALUE = {{ $value }}
      LABELS = {{ $labels }}    
  runbook: https://srerun.github.io/prometheus-alerts/runbooks/etcd-internal/etcdhighcommitdurations/
  summary: Etcd high commit durations (instance {{ $labels.instance }})
expr: histogram_quantile(0.99, rate(etcd_disk_backend_commit_duration_seconds_bucket[1m]))
  > 0.25
for: 2m
labels:
  severity: warning

Here is a runbook for the Prometheus alert rule EtcdHighCommitDurations:

Meaning #

The EtcdHighCommitDurations alert is triggered when the 99th percentile of etcd commit durations exceeds 0.25 seconds over a 1-minute period. This indicates that etcd is taking longer than expected to commit data to disk, which can lead to performance issues and increased latency in the system.

Impact #

A high etcd commit duration can have several negative impacts on the system:

  • Increased latency: As etcd takes longer to commit data, requests may be delayed, leading to increased latency and slower system response times.
  • Performance degradation: High commit durations can lead to reduced system performance, as etcd may become bottlenecked by slow disk I/O.
  • Data consistency issues: In extreme cases, high commit durations can lead to data consistency issues, as etcd may struggle to keep up with the rate of incoming requests.

Diagnosis #

To diagnose the root cause of high etcd commit durations, follow these steps:

  1. Check etcd disk usage: Verify that etcd has sufficient disk space available. High disk usage can cause slow commit durations.
  2. Investigate disk I/O performance: Check disk I/O performance metrics to determine if the disk is experiencing high latency or throughput issues.
  3. Review etcd configuration: Verify that etcd is configured correctly, including settings such as sync-commit and fsync-duration.
  4. Check for system resource contention: Verify that etcd has sufficient system resources (e.g., CPU, memory) and is not contending with other processes for resources.
  5. Check etcd logs: Review etcd logs for errors or warnings related to commit durations.

Mitigation #

To mitigate high etcd commit durations, follow these steps:

  1. Increase disk space: If disk usage is high, consider increasing available disk space or implementing disk cleanup mechanisms.
  2. Optimize disk I/O performance: Consider upgrading disk hardware or implementing disk I/O optimization techniques, such as caching or parallelizing I/O operations.
  3. Adjust etcd configuration: Consider adjusting etcd configuration settings, such as sync-commit and fsync-duration, to optimize commit performance.
  4. Resource allocation: Ensure that etcd has sufficient system resources (e.g., CPU, memory) and consider adjusting resource allocation if necessary.
  5. Monitor and analyze commit durations: Continue to monitor and analyze commit durations to identify trends and patterns, and adjust mitigation strategies as needed.
Edit this page