Time  to time you may see your backup job failed with RMAN-03009 and ORA-00245 errors just like below in your backup reports:

RMAN-00571: ===========================================================
RMAN-00569: =============== ERROR MESSAGE STACK FOLLOWS ===============
RMAN-00571: ===========================================================
RMAN-03009: failure of backup command on x channel at <sometime>

exit;
ORA-00245: control file backup operation failed

As described in MOS Doc [ID 1268725.1] starting from 11.2.0.2, RMAN fails on RAC when doing controlfile autobackup if RMAN configuration for snapshot controlfile is set to default value which is ORACLE_HOME/dbs/snapcf_<dbName><nodeId>.f. This is because of the change in 11.2.0.2 that any of the nodes in the cluster can write to the snapshot controlfile. Therefore, all nodes need access to snapshot file which comes to solution that in a RAC environment snapshot controlfile must be kept in ASM (I assume you use ASM, otherwise any shared NFS or such).

So, what you need to do is:

1. First of all, check if it is really the case by :

RMAN> SHOW ALL ;

2. If it is, configure RMAN to use a shared resource by:

RMAN> CONFIGURE SNAPSHOT CONTROLFILE NAME TO '+RECOVERY/DB1/snapcf_db1.f';

That's it.