MSA 2040 SMU Reference Guide

24 Getting started
The following figure shows the difference between rolling back the master volume to the data that existed when a
specified snapshot was created (preserved), and rolling back preserved and modified data.
Figure 2 Rolling back a master volume
Snapshot operations are I/O-intensive. Every write to a unique location in a master volume after a snapshot is taken
will cause an internal read and write operation to occur in order to preserve the snapshot data. If you intend to create
snapshots of, create volume copies of, or replicate volumes in a vdisk, ensure that the vdisk contains no more than
four master volumes, snap pools, or both. For example: 2 master volumes and 2 snap pools; 3 master volumes and 1
snap pool; 4 master volumes and 0 snap pools.
Related topics
• "Installing a license" (page 39)
• Creating a snapshot (page 71) or multiple snapshots (page 70)
• Changing a snapshot’s default mapping (page 72) or explicit mappings (page 69)
• "Deleting snapshots" (page 72)
• "Resetting a snapshot" (page 72)
• Viewing information about a snapshot (page 109), a vdisk (page 102), all vdisks (page 101), or the system
(page 95)
• "Rolling back a volume" (page 75)
• "Deleting schedules" (page 80)
MasterVolume-1
Snap Pool-1
MasterVolume-1
Snap Pool-1
Snapshot-1
(Monday)
Preserved Data
Modified Data
(Tuesday)
Snapshot-1
Modified Data
(Tuesday)
When you use the rollback feature, you
can choose to exclude the modified data,
which will revert the data on the master
volume to the preserved data when
the snapshot was taken.
(Monday)
Preserved Data
Or you can choose to include the modified
data since the snapshot was taken, which
will revert the data on the master volume
to the current snapshot.