Redundancy Policy in RMAN

Redundancy Policy in RMAN

Configuring the Backup Retention Policy

Retention Policy is of two options:
Window-Based Retention Policy
Redundancy-Based Retention Policy

Configuring a Recovery Window-Based Retention Policy:
The recovery window parameters specifies the number of days between the current time and the earliest point of recoverability.

CONFIGURE RETENTION POLICY TO RECOVERY WINDOW OF 7 DAYS;
The above can recover the database to any point withing the last week.

RMAN does not automatically delete backups rendered obsolute by the recovery window. Instead RMAN marks them as OBSOLUTE in the REPORT OBSOLUTE output.
RMAN retains all archived logs and incremental backups that are needed to recover the nonobsolete backups.

Configuring a Redundancy-Based Retention Policy:
The redundancy parameter specified the number of backups that has to be maintained for the Datafile & Controlfile by RMAN.
RMAN will mark the backups to be obsoluted , if the number of backups for a specific datafile or control file exceeds the Redundancy Setting.
RMAN keeps a track of which ones to retain and which are obsoluted.

CONFIGURE RETENTION POLICY TO REDUNDANCY 2;
The above will set RMAN to have only 2 backups of the datafile or controlfile. If a backup is taken after that then the older one will be obsoluted.

RMAN retains all archived logs and incremental backups that are needed to recover the nonobsolete backups.

Configuring Control File and Server Parameter File Autobackup
RMAN can be configured to automatically back up the control file and server parameter file whenever the database structure metadata in the control file changes and whenever a backup record is added.
The autobackup enables RMAN to recover the database even if the current control file, catalog, and server parameter file are lost.

Enabling : CONFIGURE CONTROLFILE AUTOBACKUP ON;
Disabling: CONFIGURE CONTROLFILE AUTOBACKUP OFF;

The following command will configure RMAN the autobackup to write to an ASM DiskGroup

ASM Instance :
(To create the disk group )
CREATE DISKGROUP CONTROL
NORMAL REDUNDANCY
FAILGROUP failure_group_1 DISK 'ORCL:ASMD6'
FAILGROUP failure_group_2 DISK 'ORCL:ASMD7';

RMAN :
CONFIGURE CONTROLFILE AUTOBACKUP
FORMAT FOR DEVICE TYPE DISK TO '+CONTROL';