innodb_io_capacity_max
INFO
Rule IDs: io_002
Overview
- Purpose
- Documented in the MySQL 8.4 manual as a server system variable (scope: Global). Purpose and semantics are described at the linked manual page.
- Dynamic (MySQL 8.4 reference)
- MySQL 8.4 marks this variable as dynamic (
Dynamic= Yes). Runtime changes useSET GLOBAL(global scope) orSET SESSION(session scope) — confirm syntax and persistence (SET PERSIST) in the manual. - Default value
- 2000 (MySQL 8.4)
- Version and product notes
- MariaDB and Percona Server may use different names, defaults, or dynamic behavior; verify their documentation.
- Documentation
- https://dev.mysql.com/doc/refman/8.4/en/innodb-parameters.html#sysvar_innodb_io_capacity_max
- Other vendors
What is checked
Rules that reference this variable, with their severity and what each rule detects:
- INFO
io_002: Set innodb_io_capacity_max to at least 2x innodb_io_capacity for adequate flush headroom during peak load.
Tuning guidance
- Recommended actions:
- Set innodb_io_capacity_max to at least 2x innodb_io_capacity for adequate flush headroom during peak load.
- Trade-offs: Higher I/O capacity values push more writes to disk, reducing lag and crash recovery time, but can saturate storage on spinning disks. Match settings to your storage hardware (SSD vs HDD).
Example
SET GLOBAL innodb_io_capacity_max = 4000; -- 2x innodb_io_capacity
Always validate on a non-production instance first. Use SET PERSIST (MySQL 8.0+) for changes that should survive restarts.