Here are some additional considerations regarding recovery catalogs:

1. Do not create your recovery catalog for your production database in your production database.
2. If possible, store the recovery catalog on different disk drives or even on a different machine.
3. It is good practice to create a separate database that contains only recovery catalog information. It is possible to store recovery catalog information in production database B for production database A and recovery catalog information in production database A for production database B. But this is not recommended, because the loss of one database could affect the recovery of both databases.
4. Back up the recovery catalog database.

Beginning with Oracle 11.2.0.2, for any form of database control file backup operations, Oracle no longer acquires the controlfile enqueue lock. This change requires snapshot control file accessibility to all instances in a RAC database, in contrast to a single-instance database, to successfully complete a manual or auto control file backup operation. When the snapshot control file is not accessible or does not exist across instances, the backup of control file operations, including RMAN backups, will fail with an
ORA-00245: control file backup operation failed
error.
To prevent an ORA-00245 error, the snapshot control file must be placed on a shared location or on ASM DISKGROUP, ensuring that each instance of RAC database has the read and write ability on the file. The following procedure explains the process to configure the snapshot control file on an ASM DISK GROUP:

RMAN> CONFIGURE SNAPSHOT CONTROLFILE NAME TO '+DG_RONDB/snapcf_RONDB.f';

Upon configuration, the following message will be displayed at RMAN prompt:

using target database control file instead of recovery catalog new RMAN configuration parameters:
CONFIGURE SNAPSHOT CONTROLFILE NAME TO '+DG_RONDB\snapcf_RONDB.f;
new RMAN configuration parameters are successfully stored

To display snapshot control file configuration details, connect to an RMAN prompt and execute one of the following commands:

RMAN> show all;
RMAN> show snapshot controlfile name;