Learn About Remote Virtual Disk Mirroring and Performance
When the data on the and participating in a are no longer synchronized, the of the primary virtual disk performs a copy operation to the data between the mirrored pair.
The RAID controller module owner of the primary virtual disk performs this operation in the background while processing local I/O writes to the primary virtual disk and associated to the secondary virtual disk. Because the resynchronization diverts RAID controller module processing resources from I/O activity, it can have a performance impact to the application. The defines how much processing time is allocated for synchronization activities relative to system performance.
The following guidelines might help you determine how long a synchronization priority might take and how much various synchronization priorities can affect system performance.
Synchronization Priority Rates
The following priority rates are available.
Lowest
Low
Medium
High
Highest
The lowest priority rate favors system performance, but the resynchronization takes longer. The
highest priority rate favors the resynchronization, but system performance might be compromised. The following guidelines roughly approximate the differences between the five priorities. size and
host I/O rate loads affect the synchronization time comparisons.
A resynchronization at the lowest synchronization priority rate takes approximately eight times as long as a resynchronization at the highest synchronization priority rate.
A resynchronization at the low synchronization priority
rate takes approximately six times as long as a resynchronization at the highest synchronization priority rate.
A resynchronization at the medium synchronization priority rate
takes approximately three-and-a-half times as long as a resynchronization at the highest synchronization priority rate.
A resynchronization at the high synchronization priority rate takes approximately twice as long as a resynchronization at the highest synchronization priority rate.