Disk looks like voice
record plate but they have multiple layer. And each
disk have round circle called tracks. Data could
be stored electronically in the round circle,
Magnetic heads play the most important role of reading
and writing data on the track.
At first magnetic storage device have changeable
disk and computer users replace disk. But it might
be polluted by dust and data could be easily destroyed
by human error thus the hard disk have a sealed
case which looks like recent hard disk drives. The
origin of the word hard disk drive is as follows,
At first people could only use floppy disk drives
in personal computer, but as the quantity increase
the floppy was substituted by relevant hard and
concrete meterials.
In case of not suppling electricity
to a hard disk drive, a magnetic head would be parked
in the landing zone and after electronicties is on,
it will start spinning. If a disk spins, it will
make a wind, and the shape of magnetic heads would
make the head flying to the upper part of platter
like airplane fly in the sky. If magnetic head spins
3,600 to 7,200 times per minute, the magnetic head
will make a constant flying height and read and
write data according to signal.
Specification of hard disk drive
Name
Explanation
Units
Formatted
size
Total size
of formatted disk drive in Mega Byte.
Megabite(MB)
Head
Head Total
number of data head
Cylinders
Cylinder
Total number of cylinders
Sector/Track
Total number
of sectors
Search
time
Average
access time of magnetic heads in mili-second
