HP StorageWorks 2000 Series Reference Manual page 117

Only one rollback is allowed on the same master volume at one time. Multiple
rollbacks on subsequent volumes on the same snap pool are performed sequentially;
that is, additional rollbacks are queued until the current rollback is complete.
However, after the rollback is requested, the master volume is available for use as if
the rollback has already completed.
To rollback a master volume:
1. Unmount the master volume from hosts.
2. If the rollback will include snapshot modified data, unmount the snapshot from
hosts.
3. Select Manage > Volume Management > Snapshot Services > Rollback Volume.
For each virtual disk, the virtual disk panel shows a status icon; the name, RAID
level, size, number of disk drives, and number of volumes; and utility status, if any.
4. Select a virtual disk.
The selected virtual disk's volume names, sizes, and types are displayed, and the
amount of free space.
5. Select the master volume to rollback.
6. Select the snapshot to rollback the master volume to.
7. Select whether to include or exclude data modified in the snapshot since it was
taken.
The default is Exclude, which means that the master volume will contain only the
data that existed when the snapshot was taken.
8. Click Rollback Master Volume.
When processing is complete, a message indicates whether the operation succeeded.