[compiler-guy]

Most of Google's internal development happens on a filesystem that saves absolutely everything in perpetuity. If you save it, the snapshot lives on forever--deleting stuff requires filing a ticket with justification. It is amazingly useful and has saved me many times. Version control is separate, but built on it.

When I eventually move on, I will likely find or implement something similar. It is just so useful.

[julian_t]

I used to rely on this on the old DEC systems, when editing and saving foo.dat;3 gave you foo.dat;4. It didn't save everything forever - and you could PURGE older versions - but it saved enough to get me out of trouble many times.