HP MSA 1040 HP MSA 1040 SMU Reference Guide (762784-001, March 2014) - Page 24

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. MasterVolume-1 Snapshot-1 Preserved Data (Monday) 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. Snap Pool-1 MasterVolume-1 Snapshot-1 Preserved Data (Monday) Modified Data (Tuesday) 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. Snap Pool-1 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 69) or multiple snapshots (page 68) • Changing a snapshot's default mapping (page 70) or explicit mappings (page 67) • "Deleting snapshots" (page 70) • "Resetting a snapshot" (page 70) • Viewing information about a snapshot (page 107), a vdisk (page 100), all vdisks (page 99), or the system (page 93) • "Rolling back a volume" (page 73) • "Deleting schedules" (page 78) 24 Getting started