You should always configure RMAN to back up the control file automatically after running any RMAN BACKUP or COPY command or after you make physical changes to the database that result in updates to the control file (such as adding/removing a data file). Use the SHOW command to display the current setting of the control file autobackup:
RMAN> show controlfile autobackup;
Here is some sample output:
RMAN configuration parameters for database with db_unique_name O12C are: CONFIGURE CONTROLFILE AUTOBACKUP ON;
The following line of code shows how to enable automatic backup of the control file feature:
RMAN> configure controlfile autobackup on;
The automatic control file backup always goes into its own backup set. When autobackup of the control file is enabled, if you’re using an spfile, it’s automatically backed up along with the control file.
If, for any reason, you want to disable automatic backup of the control file, you can do so as follows:
RMAN> configure controlfile autobackup off;
Note If autobackup of the control file is off, then any time you back up data file 1 (SYSTEM tablespace data file), RMAN automatically backs up the control file.