The Hard Drive

The Hard Drive
By “The Back Table”
• Hard drive - a non-volatile storage (computer
memory that can retain stored information
even when not powered) device which stores
digitally encoded data on rapidly rotating
platters with magnetic surfaces
Internal hard drive
• The first computer to include a hard drive was
invented by IBM in 1956
• Had fifty 24-inch platters, with a total capacity
for storing five million characters and an areal
density of 2000 bits per square inch.
• The data transfer rate of this first drive was
8800 bytes per second (2008 typical rate was
70 megabytes per second)
• 1980 saw the launch of the world's first
gigabyte-capacity disk drive, the IBM 3380,
which was the size of a refrigerator, weighed
550 pounds and had a price tag of US$40 000.
• In 1991 the 2.5-inch hard drive was
introduced with 100MB capacity.
• As of April 2009, the largest hard drive could
store up to 2 TB
How It Works
• The basic parts of a hard drive are the platters,
spindle and spindles motors, the read and write
heads and the head actuators.
• Platters are nothing but the glass or ceramic disk
present inside the drive where all the data is
stored magnetically.
• Data transfers from the read/write heads to the
magnetic layers of the platters, and it is then
stored on the tiny domains of the positive and
negative magnetization on both the sides of the
• Internal – two types
of connections
– IDE – Integrated Drive
– SATA– Serial Advanced
• Faster and more
efficient data transfer
• Smaller (7 pins versus
40 pins)
• External
connected through USB or firewire
Usually has an external power source
allows the user to back up or store important information
separate from the main internal hard drive, which could
become compromised by online or offline activities.
– Sensitive documents, large music files, DVD images,
movies, disk images, and even a backup of the contents of
your main internal hard drive, can all be kept securely and
safely on an external hard drive. When you are online, you
can even leave the external drive turned off.
Size, Capacity, and Speed
• Desktop
– 3.5”
– 250 GB to 1TB
– 7,200 – 15,000 rpm
• Laptop
– 2.5”
– Typically 80 GB to 200GB
– 5,400 – 7,200 rpm
Life Expectancy
• Depends on how often they are used
• 2-5 years for a computer used on a regular
• Most should last until outdated
• A hard drive needs to be defragmented.
• Defragment means to organize and resort
your files so that they can be found more
• To access click Start > Programs > Accessories
> System Tools
• Typically needs to be defragmented about
once a month.
Size, Options, Cost
– Western Digital External 1TB - $119.99
– Seagate External 1TB - $109.99
– Seagate Internal 1TB - $99.99
– Seagate Internal 500GB - $59.99
– Samsung Internal 500GB - $49.99
Size, Options, Cost
– Maxtor External 1TB - $199.99
– Seagate External 500GB - $84.99
– Seagate External 1.5TB - $149.99
Size, Options, Cost
– Maxtor External 1TB - $99.99
– Seagate Internal 1.5TB - $125.99
– Seagate Internal 320GB - $72.99
• Eventually, manufacturers will combine heat-assisted
and patterned media to produce drives that will be
capable of storing 50 to 100 terabits of data per square
inch. That's 280 to 560 times more dense than the
178.8 gigabit-per-square-inch drive coming from
Toshiba later this year. (A square inch of 100-terabit
material could hold as much data as 12,500 pickup
trucks filled with books.)
• Flash memory makers assert that their chips will start
to displace drives in notebooks over the coming years.
Why Flash?
• Fast start-up, since you don’t have to wait for the disc
platters to spin up
• Much faster access time
• Much faster boot times and application load times
• Longer life span. While drive crashes are not a risk, the
memory itself does have a life span. It is said that a typical
flash drive will have about a 10-year life span. Technically,
the technology in use in today’s hard drives has a long life
span (the actual data), however, because of the mechanical
nature of the drives, actual life span is much less.
• No mechanical parts means less power, less heat, and NO
• Speed consistency. Normal hard drives usually slow down
as they fill up, whereas flash drives can maintain constant
speed even if at peak capacity.
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