About the Oracle recovery catalog
The recovery catalog is a repository of information. RMAN uses the information in the recovery catalog to determine how to perform requested backup and restore actions.
The recovery catalog contains information about the following software components:
Data file and archive log backup sets and backup pieces.
Data file copies.
Archived redo logs and their copies.
Tablespaces and data files on the target database.
Stored scripts. These are named, user-created sequences of RMAN and SQL commands.
Oracle recommends that you use RMAN with a recovery catalog, especially if you have 20 or more data files. However, you are not required to maintain a recovery catalog with RMAN.
For information on the benefits and disadvantages of using a recovery catalog, see your Oracle documentation.