I found this fascinating article from Tom’s Hardware on how hard drives are made. The whole article (18 images with accompanying text) is pretty interesting, but the most interesting slide is this one.
Consider this little comparison: if the read/write head were a Boeing 747, and the hard-disk platter were the surface of the Earth:
- The head would fly at Mach 800
- At less than one centimeter from the ground
- And count every blade of grass
- Making fewer than 10 unrecoverable counting errors in an area equivalent to all of Ireland.