HP P4000 9.0 HP StorageWorks P4000 SAN Solution User Guide - Page 213
Using snapshots, Snapshots versus backups, Prerequisites, Using snapshots - vss provider
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13 Using snapshots Snapshots are a copy of a volume for use with backup and other applications. Snapshots are one of the following types: • Application-managed -Snapshot of a volume that is taken while the application that is serving that volume is quiesced. Because the application is quiesced, the data in the snapshot is consistent with the application's view of the data. That is, no data was in flight or cached waiting to be written. This type requires the use of the HP P4000 VSS Provider (VSS Provider). For more information, see "Requirements for application-managed snapshots" on page 216. • Point-in-time -Snapshot that is taken at a specific point in time, but an application writing to that volume may not be quiesced. Thus, data may be in flight or cached and the actual data on the volume may not be consistent with the application's view of the data. Snapshots versus backups Backups are typically stored on different physical devices, such as tapes. Snapshots are stored in the same cluster as the volume. Therefore, snapshots protect against data deletion, but not device or storage media failure. Use snapshots along with backups to improve your overall data backup strategy. Prerequisites Before you create a snapshot, you must create a management group, a cluster, and a volume to receive it. Use the Management Groups, Clusters and Volumes wizard to create them. For information, see • "Creating a management group" on page 146 • "Creating additional clusters" on page 177 • "Creating a volume" on page 208 • "The effect of snapshots on cluster space" on page 197 Using snapshots You create snapshots from a volume on the cluster. At any time you can roll a volume back to a specific snapshot, create a SmartClone volume, or use Remote Copy from a snapshot. You can mount a snapshot to a different server and recover data from the snapshot to that server. Snapshots can be used for these cases: • Source for creating backups • Data or file system preservation before upgrading software • Protection against data deletion • File-level restore without tape or backup software • Source volumes for data mining, test and development, and other data use. P4000 SAN Solution user guide 213
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