ORA-245: control file backup operation failed

In 11.2 RAC:

SQL> alter database create standby controlfile as '/home/oracle/cntrl01.ctl';

alter database create standby controlfile as 
'/home/oracle/renostdbycntrl.ctl'
*
ERROR at line 1:
ORA-245: control file backup operation failed

or

RMAN-00571: ========================================================
RMAN-00569: ============ ERROR MESSAGE STACK FOLLOWS =============
RMAN-00571: =========================================================
RMAN-03009: failure of resync command on default channel at 03/13/2015 10:19:41
ORA-00245: control file backup operation failed

Fix:-

Configure the snapshot controlfile to a shared disk:

RMAN> CONFIGURE SNAPSHOT CONTROLFILE NAME TO '<shared_disk>/snapcf_<DBNAME>.f';

RMAN> CONFIGURE SNAPSHOT CONTROLFILE NAME TO '+<DiskGroup>/snapcf_<DBNAME>.f';