Using the correct IO scheduler can increase performance and reduce the possibility of database timeouts when the system is under extreme write load. For file systems running on an SSD, or in a virtualized environment, the noop scheduler is recommended. For all other systems, the deadline scheduler is recommended. To determine which scheduler is configured on your system, run this command:
$ cat /sys/block/<block-device>/queue/scheduler
$ cat /sys/block/sda/queue/scheduler
Changing the scheduler on a running system can be done with the following command:
$ echo 'deadline' > /sys/block/sda/queue/scheduler
The change will take effect after the system is restarted. The procedure for configuring a scheduler to use at startup depends on the version of Linux. See the Linux documentation for your specific version for the correct way to configure this setting.