You can reduce the number of IOPS used to perform resynchronization on disk groups in the Virtual SAN cluster. Resynchronization throttling is a cluster-wide setting, and it is applied on a per disk group basis.
If VMs are not responding due to latency caused by resynchronization, you can throttle the number of IOPS used for resynchronization. Consider resynchronization throttling only if latencies are rising in the cluster due to resynchronization, or if resynchronization traffic is too high on a host.
Resynchronization throttling can increase the time required to complete resynchronization. Reprotection of non-compliant VMs might be delayed.
- Navigate to the Virtual SAN cluster in the vSphere Web Client.
- Select the Monitor tab and click vSAN.
- Select Resyncing Components and click Resync Throttling.
- (Optional) Click Show current resync traffic per host to view resynchronization activity.
- Select the Enable throttling for resyncing components traffic check box.
- Move the slider to set the throttle, as follows:
A general rule is to throttle the IOPS by half and allow some time for the cluster to adapt. If further action is needed, throttle the IOPS by half again until the cluster stabilizes.
- Move the slider to the right to increase the amount of IOPS allowed for resynchronization.
- Move the slider to the left to decrease the amount of IOPS allowed for resynchronization.
- Click OK.