Restoring the Server Parameter File from a Control File Autobackup

If you have configured control file autobackups, then the server parameter file is backed up with the control file whenever an autobackup is taken.
To restore the server parameter file from the control file autobackup, you must first set the DBID for your database and then use the RESTORE SPFILE FROM AUTOBACKUP command. If the autobackup is in a nondefault format, then first use the SET CONTROLFILE AUTOBACKUP FORMAT command to specify the format.

Example 19-1 Restoring the Server Parameter File from a Control File Autobackup

SET DBID 320066378;
RUN 
{
  SET CONTROLFILE AUTOBACKUP FORMAT 
    FOR DEVICE TYPE DISK TO 'autobackup_format';
  RESTORE SPFILE FROM AUTOBACKUP;
}

RMAN uses the autobackup format and DBID to hunt for control file autobackups. If a control file autobackup is found, then RMAN restores the server parameter file from that backup to its default location.
To learn how to determine the correct value for autobackup_format, see the description of CONFIGURE CONTROLFILE AUTOBACKUP FORMAT in the entry for CONFIGURE in Oracle Database Backup and Recovery Reference.