I save my raw files... right now only 2 copies on identical hard drives. In the future I hope to get a third hard drive, and also keep them in separate machines. Occasionally I've gone back to the raw files after I had an edited version (mostly on shows where I mixed multiple sources that I did when I was still pretty new to taping, and the final mix wasn't as good sounding as I can do now).
The edited version I have 2 to 3 identical copies on separate hard drives. But I have another plan that is my last resort if I encounter data loss across all local copies with any of the edited versions: I try to post them online so that other people have a copy and I would try to find someone to provide a copy back to me.