Recommendations for performing a backup

General recommendations

Avoid backing up too much data in a single dump command to reduce the risk of encountering an error that requires restarting a dump command. If the dump command encounters an error, however, you might be able to correct the error and proceed from the point where the command terminated. (See Restarting a dump command backup.)

If the filer console appears to be hung during a backup, it is because a backup can take a long time. The console becomes responsive and the prompt returns when the backup is completed.

Recommendations for minimizing backup time and data loss

You can minimize both the time required to perform a backup and the possibility of data loss. The shorter the time for the dump command to finish, the more incremental backups you can perform.

Perform frequent incremental backups to minimize the amount of unrecoverable data in case of errors.
Note
There is a disadvantage to having a large number of incremental backups. When you restore data, you must restore from all the incremental backup tapes, which requires running multiple restores and manipulating multiple tape sets.
Use local tape drives. The filer can write faster to a local tape drive than to a tape drive attached to a remote system.
Organize data to be backed up.
The dump command runs faster if the dump path specifies one of the following:
- A full volume
- Full qtrees
- A full volume excluding qtrees

Recommendations for decreasing tape backup time

Divide large volumes into smaller volumes or qtrees.
For example, if you divide a 500-GB volume into three qtrees, you can back up each qtree to a separate tape drive or run separate full backups on three different nights.
Limit the amount of data in a volume or qtree to be backed up to 200 GB.
Schedule the backups in appropriate rotations.
Schedule backups when the load on the filer is light.
Do not divide a backup into more than 15 qtrees.

Recommendations for minimizing the number of tape drives required

Because Data ONTAP supports the rmt protocol, several filers can share the same tape drive. Attach the tape drive to the filer with the most data to back up. Follow these guidelines if multiple filers back up to the same tape drive:

Use a private network for the backup so that the traffic load on the network does not slow down the backup process.
Schedule the dump command on each filer so that it starts only when no other filers are using the tape drive.

Recommendations for recording information for restores

For ease of use during a restore, you should label the backup tapes with the following information:

The dump path of each backup on a tape.
The level of each backup on a tape.
The date of each backup.
The blocking factor. This must match for backups and restores.
Tape file contents of a multifile tape. A brief description of the contents of each tape file on a multifile tape helps you locate a desired tape file for restoring.
The sequence of tape files on a multifile tape. This enables you to specify which file to restore. To specify a tape file, you need to know where in the sequence of tape files it is.
The Data ONTAP version of each backup.

Recommendation for verifying backups

If you suspect that a backup might have errors, verify the backup by performing a test restore, as described in Specifying a test restore. For information about restoring information from tape backups, see Data Restoration from Tape.