If you set
CONFIGURE CONTROLFILE AUTOBACKUP to
ON, then RMAN automatically creates a control file and an SPFILE backup after you run the
COPY commands. RMAN can also automatically restore an SPFILE, if this is required to start an instance to perform recovery, because the default location for the SPFILE must be available to all nodes in your Oracle RAC database.
If you back up the control file using the SQL*Plus
ALTER DATABASE command, then you must also create the control file backup on a device shared by all nodes.
These features are important in disaster recovery because RMAN can restore the control file even without a recovery catalog. RMAN can restore an autobackup of the control file even after the loss of both the recovery catalog and the current control file. You can change the default name that RMAN gives to this file with the
CONFIGURE CONTROLFILE AUTOBACKUP FORMAT command. Note that if you specify an absolute path name in this command, then this path must exist identically on all nodes that participate in backups.
RMAN performs the control file autobackup on the first allocated channel. Therefore, when you allocate multiple channels with different parameters, especially when you allocate a channel with the
CONNECT command, determine which channel will perform the control file autobackup. Always allocate the channel for this node first.
Oracle Database Backup and Recovery User's Guide for more information about using the control file autobackup feature