innodb_write_io_threads
INFO
Rule IDs: io_006
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 not dynamic (
Dynamic= No). It must be set inmy.cnfor on the command line; changing it requires a restart. - Default value
- 4 (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_write_io_threads
- Other vendors
What is checked
Rules that reference this variable, with their severity and what each rule detects:
- INFO
io_006: On high-core systems with write-heavy workloads, consider increasing innodb_write_io_threads to 8-16.
Tuning guidance
- Recommended actions:
- On high-core systems with write-heavy workloads, consider increasing innodb_write_io_threads to 8-16.
- 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
Configure in my.cnf (or equivalent) or server startup options, then restart.