I recommend that you create a recovery catalog for each version of the target databases that you are backing up. Doing so will save you some headaches with compatibility issues and upgrades.
I have found it easier to use a recovery catalog when the database version of the rman client is the same version used when creating the catalog.
Yes, having multiple versions of the recovery catalog can cause some confusion. However, if you are in an environment in which you have several different versions of the Oracle database, then multiple recovery catalogs may be more convenient.
Dropping a Recovery Catalog
If you determine that you are not using a recovery catalog and that you no longer need the data, you can drop it. To do so, connect to the recovery catalog database as the catalog owner, and issue the DROP CATALOG command:
$ rman catalog rcat/Pa33word1@rcat RMAN> drop catalog;
You are prompted as follows:
recovery catalog owner is RCAT
enter DROP CATALOG command again to confirm catalog removal
If you enter the DROP CATALOG command again, all the objects in the recovery catalog are removed from the recovery catalog database.
It is recommended you take a backup of the catalog before performing any drop commands or after registering databases.
The other way to drop a catalog is to drop the owner. To do so, connect to the recovery catalog as a user with DBA privileges, and issue the DROP USER statement:
$ sqlplus / as sysdba
SQL> drop user rcat cascade;
SQL*Plus does not prompt you twice; it does as you instructed and drops the user and its objects. Again, the only reason to do this is when you are certain you do not need the recovery catalog or its data any longer. Use caution when dropping a user or the recovery catalog: another good practice is that you take a Data Pump export of the recovery catalog owner before dropping it.
Querying for Output in the Data Dictionary
If you do not capture any RMAN output, you can still view the most recent RMAN output by querying the data dictionary. The V$RMAN_OUTPUT view contains messages recently reported by RMAN:
SQL> select sid, recid, output from v$rman_output
order by recid;
The V$RMAN_OUTPUT view is an in-memory object that holds up to 32,768 rows. Information in this view is cleared out when you stop and start your database. The view is handy when you are using the RMAN SPOOL LOG command to spool output to a file and cannot view what is happening at your terminal.
