Check mysql-open-files

Overview

Checks the open file usage in MySQL/MariaDB as a percentage of the configured open_files_limit. If the usage approaches the limit, the server may start refusing new connections or fail to open tables.

Important Notes:

Data Collection:

  • Queries SHOW GLOBAL VARIABLES for open_files_limit

  • Queries SHOW GLOBAL STATUS for Open_files

  • Calculates the percentage of open files relative to the limit

  • Logic is taken from MySQLTuner script:mysql_stats(), v1.9.8

Fact Sheet

Fact

Value

Check Plugin Download

https://github.com/Linuxfabrik/monitoring-plugins/tree/main/check-plugins/mysql-open-files

Nagios/Icinga Check Name

check_mysql_open_files

Check Interval Recommendation

Every 5 minutes

Can be called without parameters

Yes

Runs on

Cross-platform

Compiled for Windows

No

3rd Party Python modules

pymysql

Help

usage: mysql-open-files [-h] [-V] [--always-ok]
                        [--defaults-file DEFAULTS_FILE]
                        [--defaults-group DEFAULTS_GROUP] [--timeout TIMEOUT]

Checks the open file usage in MySQL/MariaDB as a percentage of the configured
open_files_limit. Alerts when the usage rate approaches the limit.

options:
  -h, --help            show this help message and exit
  -V, --version         show program's version number and exit
  --always-ok           Always returns OK.
  --defaults-file DEFAULTS_FILE
                        MySQL/MariaDB cnf file to read user, host and password
                        from. Example: `--defaults-
                        file=/var/spool/icinga2/.my.cnf`. Default:
                        /var/spool/icinga2/.my.cnf
  --defaults-group DEFAULTS_GROUP
                        Group/section to read from in the cnf file. Default:
                        client
  --timeout TIMEOUT     Network timeout in seconds. Default: 3 (seconds)

Usage Examples

./mysql-open-files --defaults-file=/var/spool/icinga2/.my.cnf

Output:

0.2% of open_files_limit used (80.0/32.8K).

States

  • WARN if the number of open files exceeds 85% of open_files_limit.

  • --always-ok suppresses all alerts and always returns OK.

Perfdata / Metrics

Name

Type

Description

mysql_open_files

Number

Number of regular files currently opened by the server. Does not include sockets or pipes.

mysql_open_files_limit

Number

The number of file descriptors available to MySQL/MariaDB.

mysql_pct_files_open

Percentage

Open_files / open_files_limit * 100

Credits, License