How Hard Drives work

kavinele · kavinele Fri 5 Feb 2010 - 23:48

How Hard Drives work

What is a Hard Drive
Almost
all desktop computers have a hard drive inside them, but do you really
know what they are? Many people when they hear the word hard drive,
think that it refers to the computer as a whole. In reality, though,
the hard drive is just one of many different pieces that comprise a
computer. The hard drive is one of the most important parts of your
computer because it is used as a long-term storage space for your data.
What that means, is regardless of whether or not the computer is on, or
you lose power, the data will still stay stored on this drive keeping
it safe. On the other hand, it tells you how important backing up your
data is, because if the hard drive malfunctions there is a good chance
you will lose it all.

A hard drive is an integral piece of equipment for your computer as
your operating system and all your data are typically stored there. In
the majority of the situations, if you did not have a working hard
drive, or the hard drive malfunctions, you would not be able to boot
your computer into the operating system and would get an error. If you
opened your computer case and wanted to find your hard drive, it would
look similar to the image below:

Image of a Hard Drive

How hard drives work
If
you were to open your hard drive, which would immediately void your
warranty and potentially damage it, you would see something like the
image below:

Inside a Hard Drive

A hard drive consists of the following:

Magnetic platters -
Platters are the round plates in the image above. Each platter holds a
certain amount of information, so a drive with a lot of storage will
have more platters than one with less storage. When information is
stored and retrieved from the platters it is done so in concentric
circles, called tracks, which are further broken down into segments called sectors.
Arm - The arm
is the piece sticking out over the platters. The arms will contain read
and write heads which are used to read and store the magnetic
information onto the platters. Each platter will have its own arm which
is used to read and write data off of it.
Motor - The
motor is used to spin the platters from 4,500 to 15,000 rotations per
minute (RPM). The faster the RPM of a drive, the better performance you
will achieve from it.

When a the computer wants to retrieve data off
of the hard drive, the motor will spin up the platters and the arm will
move itself to the appropriate position above the platter where the
data is stored. The heads on the arm will detect the magnetic bits on
the platters and convert them into the appropriate data that can be
used by the computer. Conversely, when data is sent to the drive, the
heads will this time, send magnetic pulses at the platters changing the
magnetic properties of the platter, and thus storing your information.
It
is important to note, that since the data stored on your hard drive is
magnetic, it is not a good idea to play with a magnet near your hard
drive How Hard Drives work Smile

Hard Drive Interfaces
A
hard drive connects to your computer through a specific type of
interface. The interface on your hard drive must match the
corresponding interface on your motherboard. If you purchase a new hard
drive that has a interface that your motherboard does not support, it
will not work in your computer. Currently there are three interfaces
that have become the standard for connecting your hard to your
computer. Some information about each of these interfaces are below.

IDE or ATA
- This is currently the most common interface used but is quickly
becoming overcome by the newer SATA interface. Hard drives using this
type of interface have speeds up to 100 Mbps.
SATA - A
newer interface that uses less bulky cables and has speeds starting at
150 Mbps for SATA and 300 Mbps for SATA II. Almost all computer
manufacturers have started using SATA drives.
SCSI - This
type of interface is typically used in a business environment for
servers. Hard Drives designed for a SCSI interface tend to have a
faster RPM which therefore provides better performance.

When buying a hard drive
When
purchasing a hard drive there are some characteristics you want to keep
in mind that will help you determine the right drive for your needs.
These characteristics are:

Seek Time -
The amount of time required to move a drive's read/write head to a
particular location on the disk. The lower the number, the better.
Access time - The actual amount of time from when a data is requested from a drive and delivered. The lower the number, the better.
RPMS - How fast the platters spin. The higher the number, the faster the drive will be.
Capacity -
The amount of storage space available on the drive. Typically most
drives purchased today will be 80 Gigabytes or greater. An 80 GB hard
drive will on average cost around 60 USD.
Interface -
How the hard drive connects to your computer. Make sure that the hard
drive's interface is supported on your computer before you purchase it.

How Hard Drives work

How Hard Drives work

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