You can probably guess I've lost data a few times from my setup. :p
Fileserver with RAID using four different disks, and I regularly sync it with offline external hard drive (I set calendar reminders). Thinking of adding DRBD to a server somewhere else, can't decide between Mum's and work.
My late father did pretty well just regularly syncing his harddrive with an external drive.
Starting a sync manually like that seems like a chore, but then you KNOW its working. Automated systems can fail silently. Guess how I know...?