[NTLUG:Discuss] OT: SCSI hard drive sizes...

[Robert Pearson]

On 10/23/06, Richard Geoffrion <ntlug at rain4us.net> wrote:
> What is it about the doubleing-in-size nature (4.5, 9, 18, 36, 73, 147
> gig)  of SCSI drives?  Why don't you see  odd sized SCSI (or SAS) drives?

Because of the nature of this "break-through".

2001 May 22
Computer Disk Storage Space
Outpaces Moore's Law
Superparamagnetic Limit Exceeded by IBM Researchers
SAN FRANCISCO — IBM announced yesterday that its researchers have
succeeded in expanding what was thought to be a fundamental
data-density limit in the most common form of computer storage
technology.
Researchers at the company's Almaden Research Center in San Jose,
Calif., say they have been able to reach far beyond a frontier known
as the superparamagnetic limit — a point at which the tiny magnetic
areas that store ones and zeros on the rotating platters used in
computer hard disks become unstable.
The company also announced that it has already begun using the new
technology in the manufacture of its most recent advanced disk drives,
which began shipping several weeks ago.
Those disks are shipping as part of its Travelstar product line of
notebook hard disks, and they have now reached densities of up to 25.7
billion bits per square inch 3.98 billion bits per square centimetre.
At this density, IBM's highest capacity drives can store 48 billion
bytes — 48 gigabytes — of data.
But IBM executives said the new magnetic materials technology
introduced with the Travelstar line would enable IBM to increase disk
density to 100 billion bits per square inch 15 billion bits per square
centimetre as soon as 2003.
Such a density achievement would make it possible for the company to
manufacture a version of its tiny 1-inch 2.5 cm Microdrive that would
store 6 GB of information, compared with its current capacity of up to
1 GB.
It will also be possible to build desktop drives capable of storing
400 GB of data and portable drives capable of storing 200 GB. Such a
portable drive could hold the equivalent of 42 DVDs.
Underlying the densities is a technique used to deposit an ultrathin
layer of ruthenium, a precious metal similar to platinum, between two
layers of magnetic material.
The resulting sandwich, in which the ruthenium layer is just three
atoms thick, is sufficient to create an effect known as
antiferromagnetic coupling, or AFC, in which a stronger and more
stable electronic field is created than with conventional single-layer
magnetic materials.
The AFC effect is already used in the manufacture of tiny magnetic
sensors that read data from a rotating disk. These sensors pick up
minute changes in magnetic field strength, which are represented by
digital ones and zeros in computer language. But IBM executives said
the company was leading the industry in introducing the new technology
in the manufacture of the disk platters themselves.
"The pace of this technology is now moving remarkably rapidly," said
Currie Munce, who holds the dual positions of director of Hard Disk
Drive Technology at IBM's Storage Technology Division and director of
Storage Systems and Technology at Almaden Research Center.
Indeed, the increase in density within the disk drive industry has
outpaced the legendary rate of Moore's Law that has marked the rate of
the advance of the semiconductor industry since the late 1960s. While
the density of transistors has been doubling every 18 months since
1997, in the storage industry, density has been doubling every 12
months.
Munce said he thought the storage industry would be able to stay on
this pace until about 2007.

[The National Post, 22 May 2001]
[The New York Times, May 2001]

This quote is from a fascinating Web site not current or being updated.
<<http://www.alts.net/ns1625/winchest.html>>

Reference reading---

Moore's Law
<<http://en.wikipedia.org/wiki/Moore's_law>>

Hard Disk - Wikipedia
<<http://en.wikipedia.org/wiki/Hard_disk>>

Interesting SCSI Speed Chart - Helps keep the models straight
<<http://en.wikipedia.org/wiki/SCSI>>