[askvictor]

The thing that's wrong with magnetic media (specifically the floppy disc and audio tape) is that the head is in contact with the medium, which slowly wears it out. It only has a certain number of uses before it dies (also, the plastics will probably disintegrate at some point). Hard disks are much more reliable for longevity. Not sure about flash (or backup tapes - I assume they've been designed with longevity in mind)...