RMAN control file backup failure

Hello all,

We are observing a strange scenario. For the RMAN backup, we are not seeing any failures at NBU end, but the DBA's are getting the following alert:

RMAN-00571: ===========================================================

RMAN-00569: =============== ERROR MESSAGE STACK FOLLOWS ===============

RMAN-00571: ===========================================================

RMAN-03009: failure of Control File and SPFILE Autobackup command on ch01 channel at 06/13/2015 13:32:24

ORA-19506: failed to create sequential file, name="c-2981266559-20150613-00", parms=""

ORA-27027: sbtremove2 returned error

ORA-19511: Error received from media manager layer, error text:

   Failed to remove, c-2981266559-20150613-00, from image catalog

 

Please can you guide me for which logs to check to unerstand the error and how to resolve this?

i am not getting any error at NBU end.

NBU master-Appliance 5230: 7.6.0.2

NBU media-Appliance 5230: 7.6.0.2

Client: LINUX red hat 5.6: 7.6.0.2

 

i have been looking for hints on all oracle and NBU forums and articles but not a clue.

please help.

 

Thanks,

Anish