We use a two stage approach to our backups; we have a dedicated area on out NetApp filer which is attached as a backup partition to our servers, we use RMAN to backup directly to the filer partition and then at regular intervals our filer contents are sent to an off-site storage facility (SunGuard).

This gives me the ability to have recent backup sets easily availaible and the security of knowing that all my data is also stored in another off-site location.

As the backups are done to disk we also benefit from fast backup and restore times.

HTH