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Oracle® Database Backup and Recovery Advanced User's Guide 10g Release 2 (10.2) Part Number B14191-02 |
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# 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:

       RMAN> BACKUP DEVICE TYPE sbt BACKUPSET ALL;

   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;

2. 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 `BACKUP` `BACKUPSET` 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.