If you have two disks then modify the script

spool log to '/u1/app/oracle/backup/flush.log';
run {
allocate channel d1 device type disk format '/rman/logfiles/%d_%u_%p';
allocate channel d2 device type disk format '/rman/logfiles/%d_%u_%p';
allocate channel d3 device type disk format '/rman/logfiles/%d_%u_%p';
BACKUP ARCHIVELOG ALL DELETE INPUT;
release channel d1;
release channel d2;
release channel d3;
}
exit;
spool log off;


This should help you to allocate multiple channels and speed up your backup process. But again, one thing be cautious, if you can spread the channels across different controllers that will give you a real gain.

When I said couple of time earlier, I ment it to be in sequential order and not in parallel. You can parallelize by opening multiple channel. If you have some knind of tape backups like Tivoli/Veritas, you can blow them to that directly rather than backing them up on to disk and then to tape.

Thanx,
Sam