Backing Up Backup Sets with RMAN

Backing Up Backup Sets with RMAN

Use the BACKUP BACKUPSET command to back up backup sets produced by other backup jobs. This command is especially useful in the following scenarios:

• Ensuring that all backups exist both on disk and on tape
• Moving backups from disk to tape and then freeing the space on disk

Note: You cannot duplex backups when running BACKUP BACKUPSET. RMAN always makes one and only one copy on the specified media when performing BACKUP BACKUPSET.

To back up backup sets from disk to tape:

1. Assuming that you have configured an automatic sbt channel, issue the BACKUP BACKUPSET command at the RMAN prompt. This example backs up all disk backup sets to tape:

2. RMAN> BACKUP DEVICE TYPE sbt BACKUPSET ALL;

3.  

This example backs up all disk backup sets to tape and then deletes the input disk backups:

RMAN> BACKUP DEVICE TYPE sbt BACKUPSET ALL DELETE INPUT;

4. Issue a LIST command to see a listing of backup sets and pieces.

BACKUP BACKUPSET and Backup Retention Policy

BACKUP BACKUPSET creates additional copies of backup pieces in a backup set by copying backup pieces from disk to tape. If you use the LIST BACKUPS command, the output contains the list of all copies (including copies created by BACKUP BACKUPSET command).

However, BACKUP BACKUPSET does not create a new backup set. In this way, BACKUP BACKUPSET is similar to using the DUPLEX or MAXCOPIES option of BACKUP. The extra copy of a backup set created by BACKUPBACKUPSET is not considered to be a new backup set, as the several copies of a backup set produced by these other forms of the BACKUP command are not separate backup sets.

For the purposes of a redundancy-based backup retention policy, a backup set is counted as one instance of backup, even if there are multiple copies of the backup pieces that make up backup set, such as when a backup set has been backed up from disk to tape. For the purposes of a recovery window retention policy, either all of the copies of a backup set are obsolete, or none of them are.

This is easier to understand if you look at the output of the LIST and REPORT commands. For example, perform the following backup:

RMAN> backup as backupset datafile 5

RMAN> backup backupset <previous backupset>;

Now, run the LIST command. The output contains the following: :

Notice that the set_stamp and set_count values remain the same, but the copy# is incremented for the new backup. To see the effect of these copies under a redundancy-based backup retention policy, use the following command:

report obsolete redundancy 1;

None of the copies is reported as obsolete because both copies of the backup set have the same same values for set_stamp & set_count.

To see the effect of these copies under a recovery window-based retention policy, use the following command:

report obsolete recovery window 1 day;

None of the copies of the backup set is reported as obsolete or based on the checkpoint_change# of this backupset, with respect to the current time and the availability of other backups.

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