Check mysql-innodb-buffer-pool-size

Overview

Checks the size of the InnoDB buffer pool in MySQL/MariaDB. Logic is taken from MySQLTuner script:mysql_innodb(), v1.9.8.

Always take care of both innodb_buffer_pool_size and innodb_log_file_size when making adjustments. For that have a look at the following output example InnoDB buffer pool / data size: 36.0GiB / 49.4GiB [WARNING]. Set innodb_buffer_pool_size >= 49.4GiB. innodb_log_file_size * innodb_log_files_in_group / innodb_buffer_pool_size = 9.0GiB * 2 / 36.0GiB = 50.0% [WARNING] (should be 25%). Set innodb_log_file_size to 4.5GiB.:

Here, buffer pool is 36 GB.
Data does not fit in, it needs 49 GB.
The check plugin complains and makes some suggestions on how to resize innodb_buffer_pool_size and innodb_log_file_size.
If we adjust innodb_buffer_pool_size to 50 GB, and innodb_log_files_in_group is set to 2 (deprecated and ignored from MariaDB 10.5.2), we should set innodb_log_file_size to 6.25 to get the 25% log file versus pool size ratio. Then both warnings should change to OK.
Attention: Assuming this is a database server with entirely/primarily InnoDB tables, you need at least 64 GB, following the rule that the InnoDB buffer pool size can be set up to 80% of the total memory in this case.

Hints:

Requires a user account with high privileges to access schemas like INFORMATION_SCHEMA. For most INFORMATION_SCHEMA tables, each MySQL user has the right to access them, but can see only the rows in the tables that correspond to objects for which the user has the proper access privileges.. So you can’t grant permission to INFORMATION_SCHEMA directly, you have to grant permission to the tables on your own schemas, and as you do, those tables will start showing up in INFORMATION_SCHEMA queries. Then this check provide correct results.
On RHEL 7+, one way to install the Python MySQL Connector is via pip install pymysql
On MariaDB 10.2.2+, innodb_buffer_pool_size can be set dynamically..
Compared to check_mysql / MySQLTuner this check currently:
- supports only simple login with username/password (not via SSL/TLS)
- does not support a connection via socket

Fact Sheet

Check Plugin Download	https://github.com/Linuxfabrik/monitoring-plugins/tree/main/check-plugins/mysql-innodb-buffer-pool-size
Check Interval Recommendation	Every 5 minutes
Can be called without parameters	Yes
Available for	Python 3, Windows
Requirements	Python module `pymysql`; User with no privileges, locked down to `127.0.0.1` - for example `monitoring@127.0.0.1`. Usernames in MySQL/MariaDB are limited to 16 chars in specific versions.

Help

usage: mysql-innodb-buffer-pool-size [-h] [-V] [--always-ok] [-H HOSTNAME]
                                     [-p PASSWORD] [--port PORT]
                                     [-u USERNAME]

Checks the size of the InnoDB buffer pool in MySQL/MariaDB.

options:
  -h, --help            show this help message and exit
  -V, --version         show program's version number and exit
  --always-ok           Always returns OK.
  -H HOSTNAME, --hostname HOSTNAME
                        MySQL/MariaDB hostname. Default: 127.0.0.1
  -p PASSWORD, --password PASSWORD
                        Use the indicated password to authenticate the
                        connection. Default:
  --port PORT           MySQL/MariaDB port. Default: 3306
  -u USERNAME, --username USERNAME
                        MySQL/MariaDB username. Default: root

Usage Examples

./mysql-innodb-buffer-pool-size --hostname localhost --username root --password mypassword

Output:

InnoDB buffer pool / data size: 36.0GiB / 49.4GiB [WARNING]. Set innodb_buffer_pool_size >= 49.4GiB. innodb_log_file_size * innodb_log_files_in_group / innodb_buffer_pool_size = 9.0GiB * 2 / 36.0GiB = 50.0% [WARNING] (should be 25%). Set innodb_log_file_size to 4.5GiB.

States

WARN if size of data does not fit into the InnoDB buffer pool.
WARN if the InnoDB log file size versus the InnoDB pool size ratio is not in the range of 20 to 30%.

Perfdata / Metrics

Name	Type	Description
mysql_innodb_buffer_pool_size	Bytes	InnoDB buffer pool size in bytes. The primary value to adjust on a database server with entirely/primarily InnoDB tables, can be set up to 80% of the total memory.
mysql_innodb_log_file_size	Bytes	Size in bytes of each InnoDB redo log file in the log group. The combined size can be no more than 512GB. Larger values mean less disk I/O due to less flushing checkpoint activity, but also slower recovery from a crash.
mysql_innodb_log_files_in_group	Number	Number of physical files in the InnoDB redo log. Deprecated and ignored from MariaDB 10.5.2.
mysql_innodb_log_size_pct	Percentage	innodb_log_file_size * innodb_log_files_in_group / innodb_buffer_pool_size * 100

Credits, License

Authors: Linuxfabrik GmbH, Zurich
License: The Unlicense, see LICENSE file.
Credits:
- heavily inspired by MySQLTuner (https://github.com/major/MySQLTuner-perl)