two RMAN tips learned when using disk

1. to delete obsolete command, I have to change the command worked for tape device from

delete noprompt obsolte;

to

delete noprompt obsolte to device type disk;

2.  When using FRA, I can't use FORMAT option as discussed here, irregardless I was happy with the conversion for device type tape  BACKUP FULL FILESPERSET 1 FORMAT 'DB%I.%d_%N_%U' DATABASE;.   Otherwise, the backupset is written to $ORACLE_HOME/dbs instead FRA location.