An occasional failure mode of
magnetic-disk drives back in the days when they were huge, clunky
washing machines. Those old dinosaur parts carried
terrific angular momentum; the combination of a misaligned spindle
or worn bearings and stick-slip interactions with the floor could
cause them to `walk' across a room, lurching alternate corners
forward a couple of millimeters at a time. There is a legend about
a drive that walked over to the only door to the computer room and
jammed it shut; the staff had to cut a hole in the wall in order to
get at it! Walking could also be induced by certain patterns of
drive access (a fast seek across the whole width of the disk,
followed by a slow seek in the other direction). Some bands of
old-time hackers figured out how to induce disk-accessing patterns
that would do this to particular drive models and held disk-drive
races.
