Hard Disk: An Introduction
Hard disk is a non-volatile data storage device that stores electronic
data on a magnetic surface layered onto hard disk platters. Word Hard
is use to differentiate it from a soft, or floppy disk. Hard disks hold
more data and can store from 10 to more than 100 gigabytes, whereas
most floppies have a maximum storage capacity of 1.4 megabytes and in
addition are faster too.
Normally term hard disk is much familiar with computers only but it is
widely used as network attached storage for large volume storage.
Furthermore, appliance of hard disk drives spread out to video
recorders, audio players, digital organizers, digital cameras, and even
in latest cellular telephones.
Reynold Johnson invented the first hard disk in 1955 for IBM 305
computer with fifty 24 inch platters and total capacity of five million
characters, and in 1956 - first commercial hard disk was launched with
5 megabyte capacity, the IBM 350 RAMAC disk drive. Within time frame of
50 years and rapid progress in technical enhancement, we have now
reached to latest 2006 - First 750 GB hard drive from (Seagate) and
First 200 GB 2.5" Hard Drive utilizing Perpendicular recording
(Toshiba).
Heart of hard disk consists of four basic components:
The Platters: Platters are the actual disks inside the drive that store
the magnetized data. Conventional platters are made of a light aluminum
alloy and coated with magnetize-able material but latest technology
uses glass or ceramic platters as they are thinner and also heat
resisting. Most drives have at least two platters and the larger the
storage capacity of the drive, the more platters there are.
The Spindle Motor: Hard disk drive consists of a spindle on which the
platters spin at a constant RPM. Moving along and between the platters
on a common arm are read-write heads. The platters in a drive are
divided by disk spacers and are clamped to a revolving spindle that
turns all the platters in a uniform motion. The spindle motor is built
right into the spindle and rotates the platters at a constant set rate
ranging from 3,600 to 7,200 RPM.
The Read/Write Heads: Read/write heads read and write data to the
platters, and each head is fixed to a single actuator shaft so that all
the heads move in harmony. Typically, only one of the heads is active
at a time either reading or writing data. When not in use, the heads
are inactive, but when in motion the spinning of the platters generate
air pressure that lifts the heads off the platters. The space between
the platter and the head is so minute that even one dust particle or a
fingerprint could disable the spin. When the platters cease spinning
the heads come to rest, at a preset position on the heads, called the
landing zone.
The Head Actuator: All the heads are attached to a single head actuator
arm, which moves the heads around the platters. The Actuator arm moves
the heads on an arc across the platters as they spin, allowing each
head to access almost the entire surface of the platter. Contemporary
hard drives use a voice coil actuator, which controls the movement of a
coil toward or away from a permanent magnet based on the amount of
current flowing through it. Fundamental structures of all hard disk are
same, and are composed of the same physical features, but their
performance depends on the quality of their inner components.
Hard Disk Failure:
Hard Disk Failure occurs when a hard disk drive malfunctions and the
accumulate data cannot be accessed. It may happen in the course of
normal operation due to an internal or external factor.
Disk failure varies and the most common is “Head Crash” where the
internal read and write head of a device touches a platter or magnetic
storage surface often grinding away the magnetic surface. Head hover
just micrometers from the platters plane which makes such collision a
common one.
This sort of crash usually invites severe data loss and unprofessional
data recovery attempts results further damage to the remaining data.
Hard drive also includes other controller electronics i.e.,
semiconductors, valves or electronic circuits, and major components
such as Platters, Spindle Motor and Head Actuator. Failure of any these
devices may cause a hard disk failure. Factors causes disk failure are
numerous, yet most common are power surges, voltage fluctuations,
electronic malfunction, physical shock, wear and tear, corrosion,
exposure to high magnetic waves, sharp impact, high temperature
exposure etc.
The phenomena of hard disk failure is raising higher and higher; as to
increase the read and write speed, today we have latest hard disk
rotating amazingly faster and this immense revolving speed generates
massive centrifugal force, a single adverse cause in the course of
normal operation can cause severe hard disk failure.
Hard Disk Data Recovery:
Hard disk data recovery is the process of recovering the trapped data
from the damage hard disk device, when it can not be accessed in normal
circumstance.
Several Techniques are used to retrieving data from damaged hard disk
and techniques vary accordingly. It can be done by moving disk drive to
a working CPU, or may have to open the disk drive and replace parts
such as read/write heads, arms and chips and sometime the platters have
to be removed and placed into another drive.
Physical damage can not be repaired by the general users, as it
requires clean and dust free lab environment, in addition proper
hardware and technical expertise; where under microscopic examination
with proper tool and techniques, the damage drive is put on to
observation for data salvaging.
In case of worse happening, do consult Data Recovery Service for saving your important data trapped within the damage device.
