Veritas Storage Foundation 5.1 SP1 Advanced Features Administrator"s Guide (5900-1503, April 2011)

Figure 17-6
Using a snapshot of a snapshot to restore a database
Original volume
V
Snapshot volume of V:
S1
Create instant snapshot S1 of volume V
1
Create instant snapshot S2 of S1
2
Original volume
V
Snapshot volume of V:
S1
vxsnap make source=S1
Snapshot volume of S1:
S2
Restore contents of V instantly from snapshot S2 and keep S1 as a
stable copy
4
Original volume
V
Snapshot volume of V:
S1
vxsnap restore V source=S2
Snapshot volume of S1:
S2
After contents of V have gone bad, apply the database to redo logs to S23
Original volume
V
Snapshot volume of V:
S1
Apply redo logs
Snapshot volume of S1:
S2
If you have configured snapshots in this way, you may wish to make one or more
of the snapshots into independent volumes. There are two vxsnap commands that
you can use to do this:
■ vxsnap dis dissociates a snapshot and turns it into an independent volume.
The snapshot to be dissociated must have been fully synchronized from its
parent. If a snapshot volume has a child snapshot volume, the child must also
have been fully synchronized. If the command succeeds, the child snapshot
becomes a snapshot of the original volume.
Figure 17-7 shows the effect of applying the vxsnap dis command to snapshots
with and without dependent snapshots.
209Administering volume snapshots
Cascaded snapshots