INTERNAL COMPONENTS OF A HARD DISK DRIVE
It should first be
mentioned that the internal components of a hard disk are very
sensitive
to dust, debris and fingerprints. It only takes a
small amount of dust on the surface of
the platters to destroy all
of the data on the hard disk. For this reason,
a hard disk
should never be opened unless in a clean room
environment.
Drive Casing
The drive casing is the
rectangular shaped box that holds all of the internal components
of
the hard disk. A cover mounts
to the casing using multiple screws.
Spindle
The spindle rotates the
platters at a certain speed measured in RPM.
Actuator Arm
The actuator arm (also
called the read/write arm) contains read/write heads near the end
of
the arm. It is the actuator arm
that helps position the read/write heads at the correct location on
the platter to read the data. The heads never actually
touch the platters
when
accessing the data. They function at
approximately 5 microns above the surface
of the
platter.
Platters
In the center
of the hard disk, there are platters which hold all of the data on
the hard
disk. A disk can contain one or more platters
depending on the capacity. Platters are
round with a hole in
the center- similar to a record used on a record player. A
spindle
with a motor holds the platters together and rotates them at
a certain speed measured
in
RPM (revolutions per
minute). This creates air pressure that lifts the read/write
heads
off the platters.
Actuator
The actuator moves the
actuator arm to the correct position on the platters using voice
coils motivated by electric currents.
When no electric current is being received, the actuator causes the
actuator arm to place the read/write heads in the parked
position.
Ribbon Cable
This cable attaches the
read/write heads to the controller board.
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