A hard disk is a storage device that uses magnetically coated platters to store data. It contains 1 or more disks with storage capacities ranging from 40GB to over 1TB. Hard disks can be either internal fixed disks inside a computer or portable removable disks that can be transferred. Data is stored using either longitudinal or perpendicular magnetic recording aligned on the disk surface. Key components include platters, read/write heads, and a spindle that rotates the platters to enable reading and writing of data in tracks and sectors. A head crash can occur if the read/write head touches the disk surface, potentially causing data loss.

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Farooq Khan
֎ Asad
֎ Safwan
֎ Basit
֎ Rehmat
& his
Team

2.  It is a storage device that used
magnetically platters to store data,
instruction and information.
 The Desktop and notebook
computer contains 1 or more hard
disks.
 It have storage capacity from 40 GB to 1.5
TB and more.
 A Hard Disk that is mounted inside the
system unit sometimes is called fixed-disk.
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3.  A Hard Disk which can remove the
medium from one computer and carry it
to another computer is called Portable-
disk.
 Hard Disk store data by two ways:
 Longitudinal Recording .
 Perpendicular Recording .
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4. Longitudinal Recording
 Hard disks stored data using,
longitudinal recording , which aligned the
magnetic particles horizontally around the
surface of the disk.
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5. Perpendicular Recording
 Hard disks stored data using, perpendicular
recording , which aligned the magnetic
particles vertically or perpendicular around
the surface of the disk .
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6. Components of Hard
Disk
 These are some components of hard disk
:
 Platters .
 Disk case.
 Read/Write Head .
 Cylinder .
 Spindle .
 Disk cache .
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7.  Platter : It is a circular, metal disk that is
mounted inside a hard disk drive. It is made
of aluminum, glass, or ceramic and is coated
with an alloy material that allows items to be
recorded magnetically on its surface.
 Before writing data , the hard disk must
be formatted .
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8.  The process of dividing the disk into tracks
and sectors , so that the operating system
can store and locate data and information on
the disk is called Formatting .
 A narrow recording band that forms a full
circle on the surface of the disk is called
Track.
 The disk’s storage locations consist of pie-
shaped sections, which break the racks
into small arcs called sectors .
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9.  The smallest unit of disk space that
stores data and information is called
Cluster .
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10.  Disk Case : The rectangular shaped disk case
holds all of the components of a hard disk drive
.
 Read/Write Head : A read/write head
 is the mechanism that reads items and
writes
 items in the drive as it barely touches
the disk’s recording surface .
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11.  Cylinder :A cylinder is the vertical section
of a track that passes through all platters .
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12. Components of Hard
Disk
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13.  Spindle : The spindle holds the platters
together and the motor rotates the platters
at their designated speed, which is
measured in RPM.
 The platters in the hard disk rotate at a high
rate of speed. This spinning, which usually is
5,400 to 15,000 revolutions per minute (rpm)
.
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14.  Disk cache : sometimes called a buffer,
consists of a memory chip(s) on a hard disk
 that stores frequently accessed items such
as data, instructions, and information .
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15. Head Crash
 A head crash occurs when a read/write head touches the
surface of a platter, usually resulting in a loss of data or
sometimes loss of the entire disk. Dirt, hair, dust, smoke, and
other particles could cause the hard disk to have a head crash
.
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