Incremental Backup Strategy Without a Backup Libra (SAP Library - Database Administration (Oracle) with SAPDBA)

Incremental Backup Strategy Without a Backup Library

Use

An incremental backup (level 1) must always be made with RMAN, however the full backup (level 0) can be made with BRBACKUP and an external backup tool, and without RMAN. The full backup is cataloged automatically as a level 0 backup.

The above solution is an alternative to the complete RMAN solution that offers better security.

For more information, see RMAN Backup Strategies and Incremental Backups After Structural Changes.

Prerequisites

RMAN Full Backup (Level 0) to Disk

You can make a full backup with RMAN and without a backup library only to disk. Afterwards, use BRBACKUP to back up the disk backup to tape. This is a two-phase backup.

Advantages:

You can use RMAN functions (such as automatic block checks).

There is less redo information in an online full backup, since RMAN checks the consistency of the data at block level, so removing the need for the BEGIN/ END BACKUP commands.

Disadvantage:

You need to back up the full backup to tape, causing extra work.

Full Backup (Level 0) with BRBACKUP or an External Tool, Without RMAN

You can make the full backup (level 0) without RMAN. After you make the full backup (using BRBACKUP or BACKINT and an external tool) it is cataloged as a level 0 backup. BRBACKUP can make a full backup directly to tape, removing the need for a second phase.

Advantages:

Increased security when you restore or recover the backup. You can recover the database without RMAN because no savesets are formed during the full backup. You can also replace the import of the last incremental backup with an import of the redo log files created since the last full backup.
Under certain conditions the backup may be faster, since RMAN is not involved in the full backup. The data is backed up directly using cpio, dd or BACKINT.

Disadvantages:

You cannot use RMAN features such as the database block check.
The commands are used in an online full backup. This produces much more redo log information. This data increases the load on the system and makes an ArchiveStuck more likely.
If you make a recovery without RMAN you may have to import a lot of redo log files since the full backup is usually only made once a week.

Incremental Backup (Level 1) to Disk with RMAN

You can also make incremental backups (level 1) with RMAN and without a backup library, but only to disk. There is no one-to-one copy of the database files; instead savesets are created which means you can only recover the savesets of an incremental backup with RMAN (see Saveset Grouping). In a second phase, back up the incremental backup to tape with BRBACKUP ( Two-Phase Backup).

Procedure

Full Backup and Incremental Backup Without Backup Library

Full Backup (Level 0) of the Database

BRBACKUP calls cpio, dd or BACKINT to back up the database. cpio or dd read the data from the disk and write it to tape. If you use the BACKINT interface, the data is transferred to external backup software that then backs up the data to the backup medium. The backup is then cataloged automatically as a full backup (level 0). This means it can be used as a reference for later incremental backups.

b) Incremental Backup (Level 1) of the Database

Since you cannot make an incremental backup directly to tape without a backup library, this step is a two-phase backup:

In the first phase, the Oracle server process reads the data from the Oracle database, and saves it to disk in a saveset.

In the second phase, BRBACKUP calls cpio, dd or BACKINT to read the data from the disk and write it to the backup medium. If you use the BACKINT interface, the data is transferred to external backup software that then backs up the data to the backup medium.

For more information, see RMAN Backup Strategies and Profile Parameters and BRBACKUP Command Options.