Rolling Forward Image Copies

Hi,
currently I test rolling forward Image copies with RMAN. The purpose is to have a second diskgroup which holds a mirror of the database files. On the image copies I daily apply backupsets.

The device for Backupsets is /mnt/acfs/back_acfsvol1/
The diskgroup Device for the image copy is '+ORCLDATAIMG' (We use OMF)

I create an image copy
run
{
allocate channel c1 DEVICE TYPE DISK FORMAT '+ORCLDATAIMG';
backup as copy database TAG 'ORCL';
release channel c1;
}

I make a backup and recover the image copy:
RUN {
DELETE NOPROMPT OBSOLETE;
allocate channel 'img_copy' DEVICE TYPE DISK FORMAT '+ORCLDATAIMG';