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MySQL Health Checks

Structured Markdown documentation to diagnose, measure, and optimize MySQL.

This page is original PmaControl documentation. It keeps a practical index structure for MySQL optimization work, without copying third-party content or depending on an external product.

Objective

A MySQL health check verifies whether the server is operationally healthy: availability, capacity, coherent limits, absence of critical signals, and minimum configuration quality.

Essential Checks

  1. Uptime and recent restarts.
  2. Connection saturation compared with max_connections.
  3. Disk-read ratio from the buffer pool.
  4. Temporary tables created on disk.
  5. Connection errors and Aborted_clients.
  6. Long locks, deadlocks, and waiting queries.
  7. Free space for datadir, binary logs, and redo logs.

Basic SQL

SHOW GLOBAL STATUS LIKE 'Uptime';
SHOW GLOBAL STATUS LIKE 'Max_used_connections';
SHOW GLOBAL STATUS LIKE 'Created_tmp_disk_tables';
SHOW ENGINE INNODB STATUS\G

Interpretation

A health check should not only output a red/green list. It must explain impact, priority, and how to confirm the diagnosis.