Originally Posted by
snootyjim
You can run automated backups onto an external drive, that's no problem.
If you have RAID though, you're relying on the computer to keep those two drives going - if anything happens, like for example the PSU blowing up, it will probably be the end of both drives rather than just one of them, and then you've lost your backup.
Okay, so you can probably send them to a data recovery firm, but by that time it's cost a fortune and you might as well have got an external drive.