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How a dump backup works

A dump backup writes file system data from disk to tape using a predefined process.

You can back up a volume, a qtree, or a subtree that is neither an entire volume nor an entire qtree.

The following table describes the process that Data ONTAP uses to back up the object indicated by the dump path:

Stage Action
1 For less than full volume or full qtree backups, Data ONTAP traverses directories to identify the files to be backed up.

If you are backing up an entire volume or qtree, Data ONTAP combines this stage with Stage 2.

2 For a full volume or full qtree backup, Data ONTAP identifies the directories in the volumes or qtrees to be backed up.
3 Data ONTAP writes the directories to tape.
4 Data ONTAP writes the files to tape.
5 Data ONTAP writes the ACL information (if applicable) to tape.

The dump backup uses a Snapshot copy of your data for the backup. Therefore, you do not have to take the storage system or volume offline before initiating the backup.

The dump backup names each Snapshot copy it creates as snapshot_for_backup.n, where n is an integer starting at 0. Each time the dump backup creates a Snapshot copy, it increments the integer by 1. The storage system resets the integer to 0 when it is rebooted. After the backup operation is completed, the dump engine deletes this Snapshot copy.

When Data ONTAP performs multiple dump backups simultaneously, the dump engine creates multiple Snapshot copies. For example, if Data ONTAP is running two dump backups simultaneously, you find the following Snapshot copies in the volumes from which data is being backed up: snapshot_for_backup.0 and snapshot_for_backup.1

Note: When you are backing up from a Snapshot copy, the dump engine does not create an additional Snapshot copy.

The dump engine does not back up inconsistent LUN clones. Inconsistent LUN clones are LUN clones whose backing Snapshot copies are missing and therefore have missing data blocks.