RMAN Retention Policy

The RMAN retention policy determines how long backups are kept for and how many copies are retained.

The retention policy can be defined in terms of:

REDUNDANCY - number of copies to retain
RECOVERY WINDOW - number of days to retain backups

The retention policy is configured by the RETENTION POLICY parameter. The default value is

CONFIGURE RETENTION POLICY TO REDUNDANCY 1;

To specify a recovery window of 1 day use:

CONFIGURE RETENTION POLICY TO RECOVERY WINDOW OF 1 DAYS;

Backup files can be marked as expired or obsolete.

Expired - RMAN has performed a crosscheck and the file cannot be found
Obsolete - based on the retention policy the file is not needed for recovery

The backup retention policy only applies to full or level 0 datafile and control file backups.

The retention policy does not directly affect archived redo logs and incremental level 1 backups. These files become obsolete when no full backups exist that need them.

Datafile backup sets cannot be deleted until all datafile backups within the backup set are obsolete.

Obsolete backups can be identified using the REPORT OBSOLETE command and deleted using the DELETE OBSOLETE command.

The retention policy can also be set to NONE

RMAN> CONFIGURE RETENTION POLICY TO NONE;

To revert to the default value use:

RMAN> CONFIGURE RETENTION POLICY CLEAR;

RMAN> crosscheck backup;

using channel ORA_DISK_1