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Oracle Database Administration II study materials
Oracle Database Administration II study resources

Oracle Database Administration II: RMAN Configuration and Backup Strategies

Oracle Database Administration II · Work through your exam, one topic at a time.

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RMAN Configuration and Backup Strategies

This domain tests how you configure RMAN persistently and choose a backup strategy that satisfies a stated recovery requirement. Expect questions on retention policies, incremental levels, archived log backups, and the difference between what RMAN reports as obsolete and what is physically deleted.

Persistent configuration

RMAN stores settings in the target control file and optionally the recovery catalog; SHOW ALL displays them and V$RMAN_CONFIGURATION exposes them. Key settings include CONFIGURE RETENTION POLICY, CONFIGURE CONTROLFILE AUTOBACKUP, channel parallelism, MAXPIECESIZE, compression, and encryption. The default retention policy is redundancy 1.

  • Redundancy keeps N backups of each file; a recovery window keeps enough backups to recover to any point in the last N days.
  • REPORT OBSOLETE only lists; DELETE OBSOLETE removes. Neither is automatic.
  • Archived log deletion is controlled separately by CONFIGURE ARCHIVELOG DELETION POLICY.
  • The fast recovery area needs DB_RECOVERY_FILE_DEST and a correctly sized DB_RECOVERY_FILE_DEST_SIZE.

Backup strategy

A level 0 backup is the incremental base. A differential level 1 backs up blocks changed since the most recent level 0 or level 1; a cumulative level 1 backs up blocks changed since the most recent level 0. Block change tracking (enabled with ALTER DATABASE ENABLE BLOCK CHANGE TRACKING) makes incremental backups faster. BACKUP DATABASE PLUS ARCHIVELOG protects the database and the redo needed to recover it.

Worked example

A 2 TB database must be recoverable to any point in the last 14 days. Configure CONFIGURE RETENTION POLICY TO RECOVERY WINDOW OF 14 DAYS, enable block change tracking and control file autobackup, run a weekly level 0 with PLUS ARCHIVELOG, and run nightly differential level 1 backups. Differential incrementals are smaller and faster; recovery needs the level 0 plus each level 1, which RMAN applies automatically. A cumulative strategy would need fewer incrementals at restore time but each backup would be larger.

Traps

CONFIGURE RETENTION POLICY CLEAR restores the default redundancy 1, not an infinite window. Deleting files outside RMAN breaks the retention calculation. Image copies cannot use backup-set compression. A retention policy does not stop the FRA from filling; space pressure can delete archived logs and make the policy unrecoverable.