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Use snapshots during SMTape backup

Contributors netapp-aaron-holt netapp-aherbin
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You should understand how snapshots are used during an SMTape baseline backup and an incremental backup. There are also considerations to keep in mind while performing a backup using SMTape.

Baseline backup

While performing a baseline backup, you can specify the name of the snapshot to be backed up to tape. If no snapshot is specified, then depending on the access type of the volume (read/write or read-only), either a snapshot is created automatically or existing snapshots are used. When you specify a snapshot for the backup, all the snapshots older than the specified snapshot are also backed up to tape.

If you do not specify a snapshot for the backup, the following occurs:

  • For a read/write volume, a snapshot is created automatically.

    The newly created snapshot and all the older snapshots are backed up to tape.

  • For a read-only volume, all the snapshots, including the latest snapshot, are backed up to tape.

    Any new snapshots created after the backup is started are not backed up.

Incremental backup

For SMTape incremental or differential backup operations, the NDMP-compliant backup applications create and manage the snapshots.

You must always specify a snapshot while performing an incremental backup operation. For a successful incremental backup operation, the snapshot backed up during the previous backup operation (baseline or incremental) must be on the volume from which the backup is performed. To ensure that you use this backed-up snapshot, you must consider the snapshot policy assigned on this volume while configuring the backup policy.

Considerations on SMTape backups on SnapMirror destinations

  • A data protection mirror relationship creates temporary snapshots on the destination volume for replication.

    You should not use these snapshots for SMTape backup.

  • If a SnapMirror update occurs on a destination volume in a data protection mirror relationship during an SMTape backup operation on the same volume, then the snapshot that is backed up by SMTape must not be deleted on the source volume.

    During the backup operation, SMTape locks the snapshot on the destination volume and if the corresponding snapshot is deleted on the source volume, then the subsequent SnapMirror update operation fails.

  • You should not use these snapshots during incremental backup.