When trying to startup an oracle instance on a Catalog Database, if you are facing errors like the following:

SQL> startup
ORACLE instance started.

Total System Global Area  643219456 bytes
Fixed Size                  2105256 bytes
Variable Size             419430488 bytes
Database Buffers          213909504 bytes
Redo Buffers                7774208 bytes
Database mounted.
ORA-16038: log 1 sequence# 619 cannot be archived
ORA-19809: limit exceeded for recovery files
ORA-00312: online log 1 thread 1:
‘/app/oracle/product/11g/databases/redo01.log’

The reason is your flash recovery area is full, you need to increase it. Try the following:

1. Startup your database if not already, it will give the same error…

2. Alter your database, then shutdown and startup again.

sqlplus "/ as sysdba"
alter system set DB_RECOVERY_FILE_DEST_SIZE = 10g;
System altered.
SQL> shutdown immediate;
SQL> startup
ORACLE instance started.

Total System Global Area  643219456 bytes
Fixed Size                  2105256 bytes
Variable Size             419430488 bytes
Database Buffers          213909504 bytes
Redo Buffers                7774208 bytes
Database mounted.
Database opened.
SQL> quit

Try your rman backups again, and they shoould work…