ORA-19606: Cannot copy or restore to snapshot control file

Hello,
when delete obsolete backups and archivelogs appears next error:

RMAN> delete obsolete;
RMAN-00571: ===========================================================
RMAN-00569: =============== ERROR MESSAGE STACK FOLLOWS ===============
RMAN-00571: ===========================================================
RMAN-03009: failure of delete command on ORA_DISK_1 channel at 12/05/2013 15:27:49
ORA-19606: Cannot copy or restore to snapshot control file

First of all check rman permanent parameters:

RMAN> show all;
RMAN configuration parameters for database with db_unique_name ORCL are:
CONFIGURE RETENTION POLICY TO REDUNDANCY 1; # default
CONFIGURE BACKUP OPTIMIZATION OFF; # default
CONFIGURE DEFAULT DEVICE TYPE TO DISK; # default
CONFIGURE CONTROLFILE AUTOBACKUP OFF; # default
CONFIGURE CONTROLFILE AUTOBACKUP FORMAT FOR DEVICE TYPE DISK TO '%F'; # default
CONFIGURE DEVICE TYPE DISK PARALLELISM 1 BACKUP TYPE TO BACKUPSET; # default
CONFIGURE DATAFILE BACKUP COPIES FOR DEVICE TYPE DISK TO 1; # default
CONFIGURE ARCHIVELOG BACKUP COPIES FOR DEVICE TYPE DISK TO 1; # default
CONFIGURE MAXSETSIZE TO UNLIMITED; # default
CONFIGURE ENCRYPTION FOR DATABASE OFF; # default
CONFIGURE ENCRYPTION ALGORITHM 'AES128'; # default
CONFIGURE COMPRESSION ALGORITHM 'BASIC' AS OF RELEASE 
'DEFAULT' OPTIMIZE FOR LOAD TRUE ; # default
CONFIGURE ARCHIVELOG DELETION POLICY TO NONE; # default
CONFIGURE SNAPSHOT CONTROLFILE NAME TO 
'/u01/app/oracle/product/11.2.0/dbhome_1/dbs/snapcf_orcl1.f'; # default

Cause: A control file copy or restore operation specified the name of the
snapshot control file as the output file. It is not permitted to
overwrite the snapshot control file in this manner. Other
methods are available to create the snapshot control file.
Action: Specify a different file name and retry the operation. If this
is a restore, then the restore conversation remains active and
more files may be specified.
Solution:

RMAN> CONFIGURE SNAPSHOT CONTROLFILE NAME TO 
'/u01/app/oracle/product/11.2.0/dbhome_1/dbs/snap_orcl1.f';
new RMAN configuration parameters:
CONFIGURE SNAPSHOT CONTROLFILE NAME TO '/u01/app/oracle/product/11.2.0/dbs/snap_orcl1.f';
new RMAN configuration parameters are successfully stored

after that we can delete obsolete files with command:

RMAN> delete obsolete;

good by :)