Disk I/O Saturation from Write Load
criticalStorage I/O capacity exhausted by high write workload. Write operations queue waiting for disk, causing latency increases and potential transaction timeouts. Often occurs during batch updates, bulk inserts, or when storage IOPS provisioning is insufficient.
mysql.innodb.data_pending_writes > 10 sustained, mysql.innodb.os_log_pending_fsyncs > 5, mysql.innodb.data_pending_fsyncs > 10, with mysql.innodb.data_writes and mysql.innodb.os_file_writes at sustained high rates
Check storage type and provisioned IOPS. Monitor mysql.innodb.data_written and mysql.innodb.os_log_written to quantify write throughput. Upgrade storage class (e.g., gp2 to gp3 or io1/io2) for higher sustained IOPS. Review innodb_flush_log_at_trx_commit setting - if set to 1 (full durability), consider 2 for better performance if some data loss is acceptable. Monitor mysql.innodb.dblwr_writes and mysql.innodb.dblwr_pages_written - high doublewrite activity indicates write amplification. Consider instance class upgrade if network bandwidth to storage is limiting.