7.5.11.3 System Monitoring

Health Monitor provides the following on-demand tables and corresponding history tables:

• system_cpu_stats and system_cpu_stats_history: CPU activity for the system and individual CPUs.

  The history table is enabled or disabled by health_monitor.system_cpu_stats_history.

• system_disk_stats and system_disk_stats_history: I/O activity for block devices.

  The history table is enabled or disabled by health_monitor.system_disk_stats_history.

• system_memory_stats and system_memory_stats_history: System memory and paging statistics.

  The history table is enabled or disabled by health_monitor.system_memory_stats_history.

• system_process_stats and system_process_stats_history: MySQL server process and thread activity.

  The history table is enabled or disabled by health_monitor.system_process_stats_history.

System statistics are enabled by default with health_monitor.system_running=ON.

The on-demand tables obtain a snapshot when queried. Their contents exist for the query and can differ between queries and connections. The health_monitor.system_sample_rate system variable controls the history sampling interval.

The default history interval is 60 seconds and the default retention is 86400 seconds. CPU and disk histories contain multiple rows per sample, depending on the number of CPUs and block devices. Process history contains one aggregate row per sample rather than every server thread.

CPU times and completed I/O counters represent accumulated activity, not an instantaneous utilization percentage or throughput rate. Compare measurements over a known interval when calculating rates. Do not sum an aggregate CPU or process row with its individual CPU or thread rows. health_monitor.system_running=OFF stops new system statistics collection. On-demand tables produce no new statistics, and previously collected history remains accessible.