Throttles for hosts and host clusters

Throttling is a mechanism to control amount of resources that are used when the system is processing I/Os on a specific host or host cluster. If a throttle is defined, the system either processes the I/O, or delays the processing of the I/O to free resources for more critical I/O.

For each type of throttle, you can either IOPS or bandwidth limit or both. The throttle limit controls whether the processing of the host I/O continues or if it is delayed for later processing. Several reasons can exist to delay processing for specific host and host clusters. For example, if a host or host cluster has I/O intensive workloads, such as data mining systems, you can create a throttle limit that automatically delays the processing of I/O operations that exceed the configured throttle. Each host in the system may have a throttle defined or you can define throttle limits for a host cluster. In case of a host cluster throttle, all the hosts in the host cluster share the throttle limit.

Note: If you are creating a host cluster, any hosts that are added cannot have throttles configured. Throttles can be applied to the entire host cluster.