RMAN-06091: no channel allocated for maintenance (of an appropriate type)

Got below error when I try to delete obsolete backups using RMAN> DELETE NOPROMPT OBSOLETE;
RMAN-00571: ===========================================================
RMAN-00569: =============== ERROR MESSAGE STACK FOLLOWS ===============
RMAN-00571: ===========================================================
RMAN-03002: failure of delete command at 04/06/2012 14:23:27
RMAN-06091: no channel allocated for maintenance (of an appropriate type)

Even I tried with below option

RMAN> delete obsolete;

RMAN> delete noprompt obsolete;

RMAN> delete force obsolete;

Solution:

Run the following to specify the device type , in my case device type is disk

RMAN> delete noprompt obsolete device type disk;

If not worked use below:

ALLOCATE CHANNEL FOR MAINTENANCE DEVICE TYPE DISK;

run

{

report obsolete;

CROSSCHECK BACKUP;

CROSSCHECK COPY;

DELETE EXPIRED BACKUP;

DELETE EXPIRED COPY;

delete obsolete;

}

release channel;

Ref: Encountered RMAN-03002 and RMAN-06091 when Deleting Obsolete Backups [ID 567555.1]

Rman Could Not Delete Obsolete Backupsets Due To Change From Sbt_tape To Disk and To New Server [ID 1287755.1]