Learning, of course, has nothing to do with laying down bits on a formatted magnetic disk.

"None of those things would be possible without the immense capacities of magnetic disk drives at the very low cost that is possible today... thanks to this spintronic sensing device."

They generally store that information separately in what is known, colloquially, as memory, either in the processor itself, in adjacent storage chips or in higher capacity magnetic disk drives.

Engineers have managed to shrink certain components within today’s magnetic disk drives down to a few dozen nanometers.

Although magnetic tape sitting in slots in a tape library uses very little energy data latency is high, spinning magnetic disk drives have lower latency but they can use up a fair amount of energy.