In reply to tnj:
I know my dad backs up his RAW files onto an external drive about once a month which he keeps at his office the rest of the time. The whole computer is also backed up on a network RAID drive which I believe re-scans once a day.
I think he did backup onto CDs initially, but the RAW files are big and its a mighty faff to keep it up. I'm pretty sure he doesn't do that anymore.
So he has a backup of all the RAW files, within 1 month up-to-date, in a separate location, and 2 copies of the RAW and jpeg files, within 1 day up-to-date, in a separate room in the house.
Personally I think he's overdoing it a bit, but for him its many years of irreplaceable photos including ones taken by his father(and a lot of scans from slides) and he started doing it when a box containing some of his favorite slides got destroyed so it makes a certain amount of sense.
He also doesn't do any initial culling, but I guess that's based on his budget for external hard drives (money vs time!)
I'm not sure if he wipes the SD card though, I know a lot of people who don't and therefore have one extra backup stored on solid state.