| How can a
3.5-inch standard
hard disk drive (HDD) possibly hold a
terabyte of
information? As manufacturers reached the
limits of hard drive capacity, consumer demand for even higher capacity drives did
not diminish. A relatively new recording
technology called
perpendicular recording, is being deployed to further increase hard
drive storage capacities.
To understand how
perpendicular recording has changed hard disk storage and increased
storage capacities, you first
need to understand conventional, longitudinal recording.
Longitudinal Recording
As indicated by the name,
longitudinal recording is a method of recording data to a hard disk drive (HDD) in such a way that the data bits are aligned horizontally
in relation to the drive's spinning
platter, which is parallel to the surface of the disk. Essentially, you are recording on a
magnetic material, where bits (a collection of magnetized particles) are
laid out end-to-end. Longitudinal recording is the actual method of how the bits
are recorded on disk platters. The direction of this magnetic charge is
horizontal to the media, meaning the north and south poles of the magnetized
particles are lined parallel to the surface of the disk. Longitudinal recording has been the standard method of recording for more than 50 years — the first commercial hard drive
was introduced in 1956. Over the years we have seen many technological changes to
longitudinal recording, which have resulted in higher-capacity drives. We've
moved from 5.25 inch drives to 2.5 inch drives, the number of platters and
heads have been reduced all the while increasing
areal density (which is the amount
of data per square inch of media). With all of these changes
however, the need to physically change the way
data was written to the drive
was also being considered to reach higher storage capacities. |
Key Terms To
Understanding Perpendicular Hard Drive Technology:
HDD
Short for hard disk drive.
hard
disk drive
The mechanism that reads and writes data on a hard disk.
longitudinal recording Longitudinal recording aligns data bits
horizontally in relation to the drive's spinning platter, parallel
to the surface of the disk.
perpendicular recording
Perpendicular recording aligns data bits vertically . perpendicular
to the disk.
superparamagnetism
The fluctuation of magnetization due to thermal agitation.
areal
density
Also called bit density. The amount of data that can be packed onto
a storage medium.
platter
A round magnetic plate that constitutes part of a hard disk. |
Storage
capacity with longitudinal recording was largely increased by decreasing the size of
the magnetic grains that make-up data bits. As the magnetic grains became
smaller, more data could then be stored on the disk. Unfortunately, magnetic
grains have their limits. By continuing to shrink them, the point where
data integrity would be compromised was on the horizon. This effect is
called the
superparamagnetic effect.
Image Source: Hitachi Global Storage Technologies -
Perpendicular Recording
The Superparamagnetic Effect
In magnetic disk drive storage technology, the superparamagnetic effect
refers to the fluctuation of magnetization
due to thermal agitation. When the areal density (the number of bits that
can be stored on a square inch of disk media) of a disk medium reaches 150
gigabits per square inch, the magnetic energy holding the bits in place on
the medium becomes equal to the ambient thermal energy within the disk drive
itself. When this happens, the bits are no longer held in a reliable state
and can "flip," and scramble the data that was previously recorded.
Because of superparamagnetism, hard drive technologies
were expected to stop growing once they reached densities of 150 gigabits per square inch. Of
course, when you see a hard drive manufacturer announce a 400GB hard drive you
may wonder what happened to the superparamagnetic effect? Actually, this type
of drive would contain three platters able to store up to a maximum of 133GB
each resulting in a 400GB HDD, it is not 400GB contained on a single
platter.
Perpendicular Recording
Realizing the limits of packing smaller magnetic grains was heading
towards occurrences of superparamagnetism, manufacturers still needed a way
to pack more data onto each drive. Perpendicular recording differs
from longitudinal recording in that data bits are aligned vertically (not
horizontally) — or perpendicular to the disk, which allows for additional
room on a disk to pack more data, thus, enabling higher recording densities.
It is widely believed that with perpendicular recording, the superparamagnetism barrier can be pushed further back allowing for continued growth in the areal density of the media for some time.
Image Source: Hitachi Global Storage Technologies -
Perpendicular Recording
Hitachi believes this recording
technology, in time, can result in a 3.5-inch disk drive capable of storing
an entire terabyte of data. Not only will perpendicular recording have an
effect on desktop storage, but on consumer devices as well, which is a major
driving force in storage sales. Smaller drives (1.8 inch), like those
used in the popular Apple iPod will also grow in capacity
.
in due time we will see the
iPod and similar devices offer 80GB of storage
and higher. Alternatively, it could be used to produce much thinner and
slimmer high capacity hard drives for consumer devices. Where you can store
3,000 on some of the higher-end
MP3 players today;
image being able to store 30,000 songs on one.
Perpendicular recording
technology however will not start and stop with changing the way data bits
are aligned. Much like the growth in capacity with longitudinal recording,
technological advancements in platters; read/write heads, and physical disk
media surfaces to name a couple, will contribute to advancements in the
capacity growth of perpendicular hard disk drives.
Perpendicular recording
technology also is not the answer to removing superparamagnetism. It has not
stopped the search for the ever elusive answer to being able to further shrink
the actual size of the magnetic grains that make up data bits.
Perpendicular recording only moves the superparamagnetism barrier back a
bit, it doesn't eliminate it. For now Perpendicular recording technology
allows for many new developments and advancements in storage capacity over
the coming years, but it too will feel eventually feel the pull of the
superparamagnetic effect; unless the physical size of a bit can be further
reduced, then again that barrier will be pushed back to meet the ever-growing
storage needs of consumers.
|
Did You Know...
According to iSuppli, the
global hard disk drive (HDD) industry set an all-time record for
growth in 2005, with shipments rising to 71 million units for
the year. |
Vangie 'Aurora' Beal
Writer, www.Webopedia.com
Last updated: April 21, 2006
Hitachi "Get Perpendicular"
A fun Macromedia Flash animation by Hitachi Global Storage Technologies called
"Get Perpendicular". Through music and animatuion this flash describes
Perpendicular technology. To view the animation you will need the Macromedia
Flash plug in.
Perpendicular Recording: A Boon for Consumer Electronics
While the hard drive industry has been using longitudinal recording successfully
for five decades, it is now within two product generations of reaching its
practical limit. For about the past decade, scientists and engineers have
pondered the potential effects of a natural phenomenon called superparamagnetism
and postulated when its presence might interfere with the progress of the hard
disk drive (HDD) industry.
Did You Know... What's Inside a Hard Drive?
All hard drives share a basic structure and are composed of the same physical
features. However, not all hard drives perform the same way as the quality of
the parts of the hard drive will affect its performance.
Seagate Technology Squeezes 160GB of capacity onto a 2.5-inch Disk
How did Seagate Technology squeeze a new-record 160GB of capacity onto a
2.5-inch notebook PC hard disk? The Momentus 5400.3 is the company's first
laptop drive that uses perpendicular recording -- data bits that stand up
instead of lying down on the platter -- to deliver areal density of 132 gigabits
per square inch.
Toshiba Storage Device Division
Tosbiba CE and HDD products.
CNN Money - Seven New Technologies That Change Every Thing
With perpendicular storage, each bit occupies less space on the surface of the
disc, so more data can be stuffed into a smaller area. In addition, because the
data is more densely packed, the read-write heads don't shuttle around as much,
so PMR drives draw less power from overworked batteries.
Wired News: Hard Drives get Vertical Boost
Seagate's new drive, the Momentus 5400.3, was being shipped as of Monday, the
Scotts Valley, California-based company said. The shift to perpendicular
recording allows it to bump up the maximum capacity of its notebook drive to 160
GB from 120 GB. |
