Rolling Back A Volume - HP P2000 G3 Reference Manual

Rolling back a volume

You can roll back (revert) the data in a volume to the data that existed when a specified snapshot was
created. You also have the option of including its modified data (data written to the snapshot since it was
created). For example, you might want to take a snapshot, mount it for read/write, and then install new
software on the snapshot for testing. If the software installation is successful, you can roll back the volume
to the contents of the modified snapshot.
CAUTION:
• Before rolling back a volume you must unmount it from data hosts to avoid data corruption. If you want
to include snapshot modified data in the roll back, you must also unmount the snapshot.
• Whenever you perform a roll back, the data that existed on the volume is replaced by the data on the
snapshot; that is, all data on the volume written since the snapshot was taken is lost. As a precaution,
take a snapshot of the volume before starting a roll back.
Only one roll back is allowed on the same volume at one time. Additional roll backs are queued until the
current roll back is complete. However, after the roll back is requested, the volume is available for use as if
the roll back has already completed.
During a roll back operation using snapshot modified data, the snapshot must be unmounted and cannot
be accessed. Unmounting ensures that all data cached by the host is written to the snapshot; if the unmount
is not performed at the host level prior to starting the roll back, data may remain in host cache, and thus
not be rolled back to the master volume. As a precaution against inadvertently accessing the snapshot, the
system also takes the snapshot offline, as shown by the Snapshot Overview panel. The snapshot becomes
inaccessible in order to prevent any data corruption to the master volume. The snapshot can be remounted
once the roll back is complete. The roll back's progress is shown in the Roll Back Volume panel.
To roll back a volume
1. Unmount the volume from hosts.
2. If the roll back will include snapshot modified data, unmount the snapshot from hosts.
3. In the Configuration View panel, right-click a volume and select Provisioning > Roll Back Volume.
4. In the main panel, set the options:
• For Volume.
• From Snapshot Volume. Enter the name of the snapshot to roll back to.
• With Modified Data. Select this option to include the snapshot's modified data in the roll back.
Otherwise, the master volume will contain only the data that existed when the snapshot was
created.
5. Click Roll Back Volume. The roll back starts. You can now remount the volume. The panel shows the roll
back's progress.
6. When the roll back is complete, if you unmounted the snapshot you can remount it.
HP StorageWorks P2000 G3 MSA System SMU Reference Guide 73