Two-Phase Backup

Use

As an alternative to a direct Oracle backup to tape you can perform a two-phase backup with full support from BRBACKUP or BRARCHIVE. This backup strategy enables you to easily make a disk backup, as well as having several copies of this and previous backups available. For a recovery, BRRECOVER can, in this case, access the disk backup directly. If a restore from tape is required, the files are directly copied to the original directories by BRRESTORE.

You can also perform the second phase of the two-phase backup with external tools – that is, backup programs, operating system tools, and so on. In this case, you have full responsibility for the complete and correct execution of this phase.

You cannot use the BACKINT interface to copy backups from raw devices or compressed disk files to tape. If you use raw devices or compressed disk files, you must save them directly to tape with BRBACKUP or operating system tools.

Features

Two-Phase Database Backup with BRBACKUP

?      Phase 1

BRBACKUP backup to disk

?      Phase 2

BRBACKUP backup from disk to tape

?      Restore phase

BRRESTORE restore from tape directly to the original directories or restore from the disk to the original directories

To back up to tape (phase 2), start BRBACKUP with the relevant command option. For more information, see -b|-backup.

Features of Two-Phase Database Backup with BRBACKUP

Advantages

Disadvantages

?      The first phase can be much shorter than a direct backup to tape.

?      In the case of a recovery the restore phase is shortened, if the backup is directly available on disk.

?      When restoring from tape, BBRESTORE can write the backed up files directly to the original directories.

?      Volume management and all other automatic actions of BRBRACKUP can be fully used in the second phase.

?      The hardware requirements (that is, disk storage and storage tapes) must be fulfilled. Additional disk storage space is required, compared to a direct tape backup.

?      You must start BRBACKUP twice for a two-phase backup.

The backup type – that is, offline or online – and the extent of the backup – that is, complete or partial – must be identical in the first and second phases. For an offline backup, the database remains open in the second phase.

Two-Phase Backup of Offline Redo Log Files with BRARCHIVE

Two-phase backup of the offline redo log files using BRARCHIVE runs analog to the BRBACKUP backup. However, you can only make a maximum of two copies to tape. We strongly recommend you to back up the offline redo log files to tape, in addition to a disk backup.

·         Phase 1

BRARCHIVE backup to disk

·         Phase 2

BRARCHIVE backup from disk to tape

·         Restore phase

BRRESTORE restore from tape directly into the original directories or direct applying of offline redo log files in a BRRECOVER recovery from disk (no restore).

To perform the BRARCHIVE backup of the offline redo log files from a disk backup to a tape volume, start BRARCHIVE with the appropriate command option. For more information, see -a|-archive.

Features of Two-Phase Backup of Offline Redo Log Files with BRARCHIVE

Advantages

Disadvantages

?      The first phase can be much shorter than direct backup to tape, so that the ORAARCH directory is emptied more quickly.

?      In a recovery, the restore phase can be much shorter, if the backup of the offline redo log files is directly available on disk. In this case BRRECOVER uses the offline redo log files directly from the disk. There is no restore.

?      When restoring from tape, BBRESTORE can write the backed-up offline redo log files directly to the ORAARCH directory.

?      The volume management of BRARCHIVE can be fully used in the second phase of the backup.

?      A maximum of two copies of the offline redo log files can be backed up to tape, regardless of the way in which the offline redo log files are backed up: directly to tape or with a disk backup.

?      Additional storage space and storage tapes are required.

?      You must start BRARCHIVE twice for a two-phase backup.