Chapter 6. I/O Scheduling

You can use an input/output (I/O) scheduler to improve disk performance both when Red Hat Enterprise Linux 7 is a virtualization host as well as when it is a virtualization guest.

6.1. I/O Scheduling with Red Hat Enterprise Linux as a Virtualization Host

When using Red Hat Enterprise Linux 7 as a host for virtualized guests, the default deadline scheduler is usually ideal. This scheduler performs well on nearly all workloads.
However, if maximizing I/O throughput is more important than minimizing I/O latency on the guest workloads, it may be beneficial to use the cfq scheduler instead.