Now… as it happens, that's not quite completely true. When we moved to San Francisco we made paranoid backups of everything and packed up multiple copies with us as well as shipping various disks with the movers. Not all of these survived the journey, but as it turned out, most of the data that I was seriously concerned about losing, the really old stuff that would be impossible to replace, that isn't in the working set of any of our current machines, it turns out is in fine shape.