Verifying the Disk I/O Scheduler on Linux 7 Systems

Disk I/O schedulers reorder, delay, or merge requests for disk I/O to achieve better throughput and lower latency.

Linux has multiple disk I/O schedulers available, including deadline, noop, anticipatory, and Completely Fair Queuing (cfq) on Oracle Linux 7, Red Hat Enterprise Linux 7, and SUSE Linux Enterprise Server 12 systems. You should consult with your storage vendor for the appropriate I/O scheduler configuration to achieve best performance on Oracle Automatic Storage Management (Oracle ASM).

In general, Oracle recommends that you set the I/O Scheduler to deadline for rotating storage devices (HDDs) and to none for non-rotating storage devices such as SSDs and NVMe on Oracle Linux 7, Red Hat Enterprise Linux 7, and SUSE Linux Enterprise Server 12 systems.

On each cluster node, enter the following command as root to verify the configured disk I/O scheduler value.

cat /sys/block/${ASM_DISK}/queue/scheduler
noop [deadline] cfq

In this example, the default disk I/O scheduler is deadline and ASM_DISK is a rotational Oracle ASM disk device.

Note:

Contact your storage vendor for more information about how to configure I/O scheduler on Linux for your storage devices.