Dell PowerVault MD3820f - Manual (Page 141)

4. Do one of the following:
– If you want to disable the schedule, de-select Enable Snapshot Image Scheduling.
– If you want to use a different existing schedule, click Import settings from existing schedule. The
Import Schedule Settings dialog is displayed. Select the new schedule you want to import from
the Existing schedules table and then click Import.
– If you want to edit the schedule, modify the schedule settings. For more information on the
schedule settings, see the online help.
5. Click OK to apply your changes to the schedule for the snapshot group or consistency group you
selected.
Performing Snapshot Rollbacks
You can rollback snapshot operations by either:
• Creating a snapshot virtual disk of a snapshot image, which allows you to retrieve deleted files from
that snapshot virtual disk (the base virtual disk remains undisturbed).
• Restoring a snapshot image to the base virtual disk, which allows you to roll back the base virtual disk
to a previous point-in-time.
NOTE: The host will have immediate access to the new-rolled-back base virtual disk, but the
existing base virtual disk will not allow the host read-write access after the rollback is initiated. You
can create a snapshot of the base virtual disk just before you start the rollback to save the pre-
rollback base virtual disk for recovery purposes.
Snapshot images are useful any time you want to roll back to a known good data set at a specific point in
time. For example, before performing a risky operation on a virtual disk, you can create a snapshot image
to enable “undo” capability for the entire virtual disk. You can start a rollback from the following types of
snapshot images:
• Snapshot image of a base virtual disk, which allows you to roll back the base virtual disk associated
with a snapshot group to a previous state.
• Consistency group snapshot image, which allows you to roll back all or select member virtual disks of
the consistency group to a previous state.
Snapshot Rollback Limitations
• The rollback operation does not change the content of the snapshot images that are associated with
the base virtual disk.
• You cannot perform the following actions when a rollback operation is in progress:
– Delete the snapshot image that is being used for the rollback.
– Create a new snapshot image for a base virtual disk that is participating in a rollback operation.
– Change the associated snapshot group’s Repository-Full Policy.
• You cannot start a rollback operation when any of these operations are in progress in the storage
array:
– Expanding the capacity of a disk group.
– Virtual disk Expansion (VDE) to increase the capacity of a virtual disk.
– Migrating a disk group to a different RAID level.
– Changing the segment size of a virtual disk.
• You cannot start a rollback operation if the base virtual disk is participating in a virtual disk copy.
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