Using the RMAN Recovery Catalog - OCP: Oracle Database 12c Administrator Certified Professional - page 169

■ Another benefit is that the recovery catalog also makes global scripting of RMAN
operations much easier.
You simply store the scripts in the recovery catalog and call them as needed.
■ The recovery catalog also enables a few RMAN operations not available without it,
like using the KEEP FOREVER option (discussed in Chapter 3, “Configuring and Backing
Up Oracle Databases Using RMAN”) or keeping RMAN-related records for a period
of time greater than a year.
■■ The recovery catalog can make some recovery operations somewhat easier, such as
recreation of a control file.
As you can see, the recovery catalog adds to the overall RMAN architecture nicely. It
provides redundancy and additional features that make it very useful. Not all environments
will need a recovery catalog. If you have just one or two databases, then a recovery catalog
may be more trouble than it's worth. If you have a large environment, though, the recovery
catalog can make managing that environment much easier.

Confusing RMAN

Database duplication can cause the recovery catalog all sorts of problems if you are not
careful. This is because each database in the recovery catalog is uniquely identified by its
database ID, or DBID. If you duplicate a database manually, you must change the DBID of
the newly created duplicate database with the Oracle NID utility. If you do not do this and
you register the new database in the recovery catalog, RMAN will get confused as to who
the individual catalog records belong to. This can put your ability to recover your database
with RMAN at risk. Note that when you do an RMAN database duplication, it will change
the DBID for you automatically when the duplication is complete.

The recovery catalog provides a number of views (called recovery catalog views ) into
the metadata contained therein. The OCP exam will likely not expect you to memorize
these views, but it's still best to be aware of them. All the recovery catalog views start with
an RC_ prefix and then end with a descriptive name of the data contained in the view. The
following are some more popular recovery catalog views:
■ RC_DATABASE
■ RC_BACKUP_PIECE
■ RC_BACKUP_PIECE_DETAILS
■ RC_ARCHIVED_LOG