How to change InnoDB log file size in MySQL or MariaDB

Changing the InnoDB redo log size gives the server more room to absorb write bursts before it has to checkpoint dirty pages back to the data files. That can reduce flush pressure and write stalls on busy systems, but larger redo logs also mean more work during crash recovery after an unclean shutdown.

InnoDB records committed changes in the redo log before the modified pages are flushed to the tablespace. Current MySQL releases size redo as total capacity through innodb_redo_log_capacity and keep the files in a #innodb_redo directory by default, while current MariaDB releases still size redo with innodb_log_file_size and keep the files as ib_logfile* in the redo log directory.

The exact procedure depends on version. MySQL 8.0.30 and newer can resize redo online, and current MariaDB documentation marks innodb_log_file_size as dynamic from MariaDB 10.9 onward. Older MySQL and older MariaDB releases still need a clean stop, a config change, and a restart with the old redo files moved out of the way. Record the current paths first, and make sure the redo directory has enough free space for the new size.

1. Identify the server product and version before changing any redo settings.

   $ mysql --table -u root -p -e "SELECT VERSION() AS version, @@version_comment AS comment;"
   +---------+------------------------------+
   | version | comment                      |
   +---------+------------------------------+
   | 8.4.8   | MySQL Community Server - GPL |
   +---------+------------------------------+

   On MariaDB, the same command reports a version string such as 11.4.10-MariaDB and a comment such as mariadb.org binary distribution.

2. Record the current redo settings and directories.

   $ mysql --table -u root -p -e "SHOW GLOBAL VARIABLES WHERE Variable_name IN ('datadir','innodb_log_group_home_dir','innodb_log_file_size','innodb_log_files_in_group','innodb_redo_log_capacity');"
   +---------------------------+-----------------+
   | Variable_name             | Value           |
   +---------------------------+-----------------+
   | datadir                   | /var/lib/mysql/ |
   | innodb_log_file_size      | 50331648        |
   | innodb_log_files_in_group | 2               |
   | innodb_log_group_home_dir | ./              |
   | innodb_redo_log_capacity  | 104857600       |
   +---------------------------+-----------------+

   On current MariaDB releases, innodb_redo_log_capacity is absent and innodb_log_files_in_group may also be absent because MariaDB deprecated and removed that setting after the redo layout changed.

3. Choose a target size that matches the workload.

   Larger redo logs reduce checkpoint pressure during sustained writes, but they also lengthen crash recovery because more redo may need to be scanned and applied on startup.

4. Confirm free disk space in the redo log directory before resizing.

   $ df -h /var/lib/mysql
   Filesystem      Size  Used Avail Use% Mounted on
   /dev/vda1        59G   20G   36G  36% /var/lib/mysql

   If innodb_log_group_home_dir is ./, use the datadir path. If innodb_log_group_home_dir points somewhere else, check that directory instead.

5. Create or edit a late-loaded configuration drop-in so the new size survives restarts.

   $ sudoedit /etc/mysql/conf.d/z-redo-log.cnf

   MariaDB on Debian or Ubuntu commonly uses /etc/mysql/mariadb.conf.d/z-redo-log.cnf.
   RHEL-family systems commonly use /etc/my.cnf.d/z-redo-log.cnf.

6. Add the redo setting that matches the server branch you identified.

   MySQL 8.0.30 and newer use innodb_redo_log_capacity as total redo space. MariaDB and older MySQL releases use innodb_log_file_size. Current MariaDB releases default to one redo file, so do not assume ib_logfile1 exists.

   [mysqld]
   innodb_redo_log_capacity=256M

   [mariadb]
   innodb_log_file_size=256M

   For MySQL 8.0.29 and older, place innodb_log_file_size=256M under [mysqld] instead of using innodb_redo_log_capacity.

7. If the server is MySQL 8.0.30 or newer, apply the new total redo capacity online.

   $ mysql --table -u root -p -e "SET GLOBAL innodb_redo_log_capacity = 268435456; SHOW GLOBAL VARIABLES LIKE 'innodb_redo_log_capacity';"
   +--------------------------+-----------+
   | Variable_name            | Value     |
   +--------------------------+-----------+
   | innodb_redo_log_capacity | 268435456 |
   +--------------------------+-----------+

   When innodb_redo_log_capacity is defined, MySQL ignores innodb_log_file_size and innodb_log_files_in_group for sizing. The runtime change is immediate, but the configuration file still needs the same value for persistence.

8. If the server is MariaDB 10.9 or newer, apply the new redo file size online and wait for the resize to complete.

   $ mariadb --table -u root -p -e "SET GLOBAL innodb_log_file_size = 268435456; SHOW GLOBAL VARIABLES LIKE 'innodb_log_file_size';"
   +----------------------+-----------+
   | Variable_name        | Value     |
   +----------------------+-----------+
   | innodb_log_file_size | 268435456 |
   +----------------------+-----------+

   Current MariaDB documentation marks innodb_log_file_size as dynamic from MariaDB 10.9 onward. The resize runs in the background, so keep polling the variable until it shows the new value and leave the same size in the config file so a restart does not fall back to the old setting.

9. If the server is older MySQL or older MariaDB, stop it cleanly before replacing redo files.

   $ sudo systemctl stop mysql

   Replace mysql with mariadb or mysqld if that is the service unit on the host.

10. On older releases, move the existing redo files out of the redo log directory before starting the server again.

    $ sudo mv /var/lib/mysql/ib_logfile0 /var/lib/mysql/ib_logfile0.bak
    $ sudo mv /var/lib/mysql/ib_logfile1 /var/lib/mysql/ib_logfile1.bak

    Current MariaDB releases usually keep only ib_logfile0, while older MySQL releases commonly use both ib_logfile0 and ib_logfile1. Move the files that actually exist in the directory reported by innodb_log_group_home_dir or datadir.

11. If you used the older-release path, start the database service again after moving the redo files.

    $ sudo systemctl start mysql

    For the online-resize path on MySQL 8.0.30+ or MariaDB 10.9+, no immediate restart is required for the live change itself. Leave the matching value in the config file and verify restart persistence during the next planned maintenance window instead of forcing an outage just to reload the same setting.

12. Verify that the running server now reports the intended redo setting.

    $ mysql --table -u root -p -e "SHOW GLOBAL VARIABLES LIKE 'innodb_redo_log_capacity';"
    +--------------------------+-----------+
    | Variable_name            | Value     |
    +--------------------------+-----------+
    | innodb_redo_log_capacity | 268435456 |
    +--------------------------+-----------+

    On MariaDB or older MySQL, check SHOW GLOBAL VARIABLES LIKE 'innodb_log_file_size'; instead.

13. Confirm the on-disk redo layout matches the server branch you changed.

    $ ls -ld /var/lib/mysql/#innodb_redo
    $ ls -1 /var/lib/mysql/ib_logfile*

    MySQL 8.0.30 and newer keep redo files in the #innodb_redo directory. MariaDB and older MySQL releases keep the redo files as ib_logfile* in the redo log directory. Run the command that matches the branch you changed.