Resolving High Read Latency in Production Cluster: A Comprehensive Troubleshooting Approach

Problem:

The client is experiencing high read latency in their production cluster monitoring. They are seeking assistance in identifying the cause of this latency and resolving it to prevent potential outages.

Process:

Steps and measures undertaken to investigate the issue:

• Initial Assessment:
  • Requested logs/config from all nodes.
  • Observed server overload or potential network issues.
• Configuration Review:
  • Identified unnecessary line in commitlog_archiving.properties.
  • Advised on seed node configuration best practices.
• Additional Information Requested:
  • Requested network setup, disk IO, CPU, and memory usage details.
  • Suggested examining activity at 5:30 and providing higher quality charts.
  • Asked for hardware specifications of Cassandra nodes.

Solution:

Suggestions provided to the client for resolution and next steps:

• The expert proposed additional analysis steps to diagnose potential causes of latency.
• They recommended examining GC logs for long pauses and suggested switching to G1 Garbage Collector (GC) or tuning the existing CMS GC settings.
• Increasing heap size and dedicating servers exclusively to Cassandra were advised as potential performance improvements.
• The expert suggested reviewing and potentially adjusting cron and batch jobs that might impact system performance.
• Manual compaction and cleanup processes were recommended to optimize data storage and retrieval efficiency.
• Monitoring disk IO utilization and network activity was advised to identify potential bottlenecks or irregularities in system performance.

Conclusion:

The resolution of the high read latency issue in the client’s production cluster remained incomplete despite the comprehensive solution steps provided by the expert. The lack of complete information hindered the diagnostic process, as the client only provided partial requested data. While the expert made thorough recommendations addressing potential causes of latency, including configuration adjustments, performance tuning, and data analysis, the issue persists due to the absence of critical details and the current non-impactful nature of the latency on applications.