Tell me your worst hard-drive nightmares.

Oh boy, I work as a system administrator and that actually happened to me a couple of times. Foolish of me, of course, but since then I always use backup software. Handy Backup is good - it's the most simple in configuration and powerful hdd image backup utility I've ever used. So, if you still don't have any backup software on your server, it's time to think of it.