How to roll forward image copies using RMAN

Recovery Manager (RMAN) is a utility that can be used to backup and recovery your database and it simplifies backing up, restoring, and recovering database or database files

Oracle RMAN can be used to roll forward the copy to the point in time of the most recent level 1 incremental backup by applying level 1 incremental backups to an older image copy. This will help reducing recovery time. To roll forward processes all changes between SCN of original image and incremental backup are applied to the image copy.

When using Roll forward image no need to restore the database instead just switch to updated image copy this will reduce restore time and recovery will be minimal.

run {
allocate channel c1 device type disk;
recover copy of database with tag 'rman_incr_backup';
backup incremental level 1 for recover of copy with tag ‘rman_incr_backup' database;
}

The TAG is used to identify which incremental backups are applying to which image copies.

Note that when the backup runs first time there is no level 0 exists to apply incremental backups. Therefore, it will create level 0 image copy of the database. Going forward it will create level 1 incremental backup and will update previous image copy.

You can also use compression during roll forward image copies using below example

run {
allocate channel c1 device type disk;
recover copy of database with tag ‘rman_incr_backup';
backup as compressed backupset incremental level 1 for recover of copy with tag ‘rman_incr_backup' database;
}

In case if you need to switch the database to image copy you then “shutdown database” and “startup mount”

SQL> shutdown immediate;
SQL> startup nomount;

By using below RMAN command, you can switch the database to image copy

run {
allocate channel c1 device type disk;
switch database to copy;
recover database;
alter database open;
}

When using FRA (Fast Recovery Area) make sure you have has enough space to keep take full image copy database backup.

The Block change tracking will help to improve performance of the incremental backups and you can check the status and enable using below command. 

SQL> select status from v$block_change_tracking;
SQL> alter database enable block change tracking using file '/oracle/oradata/TESTDB/block_change_tracking_file.dbf' reuse;

You can use below command to disable Block change tracking

SQL> alter database disable block change tracking;

Thanks & Regards

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