Inside a Hard Disk
The best way to understand how a hard disk
works is to take a look inside. (Note that OPENING A HARD DISK RUINS IT,
so this is not something to try at home unless you have a defunct drive.)
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Here is a typical hard-disk drive:
It is a sealed aluminum box with controller
electronics attached to one side. The electronics control the read/write
mechanism and the motor
that spins the platters. The electronics also assemble the magnetic
domains on the drive into bytes (reading) and turn bytes into magnetic
domains (writing). The electronics are all contained on a small board that
detaches from the rest of the drive:
Underneath the board are the connections
for the motor that spins the platters, as well as a highly-filtered vent
hole that lets internal and external air pressures equalize:
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Removing the cover from the drive reveals
an extremely simple but very precise interior:
In this picture you can see:
-
The platters, which typically spin
at 3,600 or 7,200 rpm when the drive is operating. These platters are
manufactured to amazing tolerances and are mirror-smooth (as you can see
in this interesting self-portrait of the author... no easy way to avoid
that!).
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-
The arm that holds the read/write
heads is controlled by the mechanism in the upper-left corner, and is
able to move the heads from the hub to the edge of the drive. The arm
and its movement mechanism are extremely light and fast. The arm on a
typical hard-disk drive can move from hub to edge and back up to 50
times per second -- it is an amazing thing to watch!
In order to increase the amount of
information the drive can store, most hard disks have multiple platters.
This drive has three platters and six read/write heads: :
The mechanism that moves the arms on a hard
disk has to be incredibly fast and precise. It can be constructed using a
high-speed linear motor.
Many drives use a "voice coil" approach --
the same technique used to move the cone of a
speaker on your
stereo is used to move the arm.
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مدرسة
الكمبيوتر
It is a sealed aluminum box with controller
electronics attached to one side. The electronics control the read/write
mechanism and the motor
that spins the platters. The electronics also assemble the magnetic
domains on the drive into bytes (reading) and turn bytes into magnetic
domains (writing). The electronics are all contained on a small board that
detaches from the rest of the drive:
Underneath the board are the connections
for the motor that spins the platters, as well as a highly-filtered vent
hole that lets internal and external air pressures equalize:
www.tartoos.com
Removing the cover from the drive reveals
an extremely simple but very precise interior:
In this picture you can see:
Many drives use a "voice coil" approach --
the same technique used to move the cone of a
speaker on your
stereo is used to move the arm.
www.tartoos.com
