Eli: I am not familiar with rdiff-backup, and I must say I like that rsnapshot gives me whole snapshots of files at each point in time - I can just grab the file I need and copy into place, but the generations don't take up much space.

LinuxJedi: I don't usually keep the drive mounted, my backups are on here so really I'd like the disk in a fireproof safe underground but just settling for disconnected and therefore inaccessible suits me too.