How the dump command works

What the dump command does

The dump command writes file system data from disk to tape. It is optimized for data restoration to a filer using the Data ONTAP restore command.

Kinds of backups

There are three kinds of backups:

Full volume backup, where you back up an entire volume
Full qtree backup, where you back up an entire qtree
Miscellaneous backup, where you back up a subtree that is neither an entire volume nor an entire qtree

The backup process

Data ONTAP uses the process described in the following table 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 files to be backed up. If you are backing up an entire volume or qtree, Data ONTAP combines this step with Step 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 access control list (ACL) information (if applicable) to tape.

How the dump command uses snapshots in backing up data

The dump command uses a snapshot of your data for the backup, so you do not need to take the filer or volume offline before initiating the backup.

The dump command names each snapshot it creates snapshot_for_backup.n.

n is an integer starting at 0.
Each time the dump command creates a snapshot, it increments the integer by 1.
The filer resets the integer to 0 when it is rebooted.

When Data ONTAP executes multiple dump commands simultaneously, the dump commands create multiple snapshots. For example, if Data ONTAP is running two dump commands simultaneously, you find these snapshots 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, dump does not create an additional snapshot.