Configuring the RMAN Snapshot Control File Location

The snapshot control file is a copy of a database control file that RMAN creates in an operating system-specific location.

RMAN creates the snapshot control file so that it has a consistent version of a control file to use when either resynchronizing the recovery catalog or backing up the control file.

For effective backup and recovery operations, the RMAN snapshot control file must be on shared storage that is accessible by all database nodes in a cluster. Run the following RMAN command to determine the configured location of the snapshot control file:

SHOW SNAPSHOT CONTROLFILE NAME;

You can change the configured location of the snapshot control file. For example, on Linux and UNIX systems you can specify the snapshot control file location in Oracle ASM, for example, by entering the following at the RMAN prompt:

CONFIGURE SNAPSHOT CONTROLFILE NAME TO '+RECODG/Oracle SID/snap_prod.cf';

This command sets the configuration for the location of the snapshot control file for every instance of your cluster database. Therefore, ensure that the directory location is shared by all nodes that perform backups.

The CONFIGURE command creates persistent settings across RMAN sessions. Therefore, you do not need to run this command again unless you want to change the location of the snapshot control file.

To delete a snapshot control file you must first change the snapshot control file location, then delete the file at the older location, as follows:

CONFIGURE SNAPSHOT CONTROLFILE NAME TO 'new_name';
DELETE COPY OF CONTROLFILE;