168 Configuration: Premium Feature—Snapshot Virtual DisksThe associated snapshot repository virtual disk must have sufficient capacityto process the rollback operation and the write operations from the host. Atmost, the snapshot repository virtual disk may need twice the size of the basedisk, plus additional metadata space equaling approximately 1/1000th (thatis, 0.1%) of the Base volume capacity.NOTE: Due to host server write operations, the content in the snapshot virtual diskmay have changed since creation of the snapshot. The rollback operation includesany changes made to the snapshot after it was created.You can set priority for a rollback operation. Higher priority allocates moresystem resources for the rollback operation and affects overall systemperformance.Rules and Guidelines for Performing a Snapshot RollbackThe following rules and guidelines apply to performing a snapshot rollback:• Rolling back a base virtual disk to a snapshot virtual disk does not affectthe contents of the snapshot virtual disks.• Only one snapshot rollback operation can be performed at a time.• While a base virtual disk that is undergoing a rollback, you cannot create anew snapshot virtual disks from that base virtual disk.• A snapshot rollback cannot be started while any of these operations areunderway:– Virtual Disk Capacity Expansion– Virtual Disk Expansion (VDE)– RAID Level Migration– Segment Size Migration– Virtual Disk Copy– Role Reversal (in remote replication)• If the base virtual disk is a secondary virtual disk in a remote replication,you cannot perform a snapshot rollback.• If any capacity used in the associated snapshot repository virtual diskcontains unreadable sectors, the snapshot rollback fails.
