open_files_limit
INFO
Rule IDs: os_007
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
- auto-sized based on max_connections (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/server-system-variables.html#sysvar_open_files_limit
- Other vendors
What is checked
Rules that reference this variable, with their severity and what each rule detects:
- INFO
os_007: Increase OS file descriptor limit (ulimit -n) to at least match open_files_limit in MySQL.
Tuning guidance
- Recommended actions:
- Increase OS file descriptor limit (ulimit -n) to at least match open_files_limit in MySQL.
- Trade-offs: OS tuning (swap, THP, NUMA, I/O scheduler) operates outside MySQL but directly affects database performance. Changes require root access and may need a reboot.
Example
Configure in my.cnf (or equivalent) or server startup options, then restart.