Your hard drive is a precise piece of electronic equipment. The discs
(known as platters) spin as fast as 15,000RPMs and
the heads used to read the disks “fly” above
them at fractions of a millimeter. But, the principle behind a hard
drive is relatively simple.
One or more platters are mounted on a spindle inside
the hard drive case. Both side of the platters are covered with a magnetic
material. The spindle is mounted to a motor that spins the platters.
Mounted to the end of an arm are the heads.
The arm moves back-and-forth across the platters to position the head,
much like a record player.
The heads read and write the data to the platters by detecting or changing
the characteristics of the magnetic material. Similar to a CD, the data
is laid out in tracks (also called cylinders)
on the platters.
To protect the magnetic material, the heads
do not touch the platters when they are spinning. They “float” fractions
of a millimeter above them on a cushion of air.
