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Skriven 2006-01-28 11:48:58 av TOM WALKER (1:123/140)
Ärende: Winchester Hard Drives
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 News Story by Frank Hayes

OCTOBER 21, 2002 (COMPUTERWORLD) - The disk drive wasn't a new idea 50
years ago. It just wasn't seen as necessary. Punch cards and magnetic tape
could store unlimited data, though access to any particular item was slow.
Magnetic drum devices, which stored bits of information on the surface of a
rotating metal drum, could store between 2KB and 8KB of data and allowed
quick random access. Who would ask for more?

The U.S. Air Force, that's who. In 1953, an Air Force supply depot in Ohio
wanted instant access to 50,000 inventory records—far more than drums could
hold, and far faster than tape could deliver. A team of IBM engineers in
San Jose spent the next year designing a 5MB device with a stack of 50
2-ft.-wide disks spinning at 3,600 rpm, using compressed air to keep the
single read/write head from crashing onto a disk surface.

First Words on Disk

On Feb. 10, 1954, the engineers wrote and read back the first words stored
successfully on a hard drive: "This has been a day of solid achievement."
And the mainstay of modern mass storage was born.

IBM's RAMAC 305 gave the company an early lead in what Big Blue called
DASD, or direct-access storage devices. But by 1962, other vendors were
making mainframe disk-drive systems, and drive sizes had climbed to 28MB.
The drives made online transaction processing practical, since businesses
could now access large amounts of inventory and customer data in real time
instead of using batch processing.

But as the volume of online data grew, managing storage became a major
issue. Drive capacity was still limited, so punch cards and half-inch tape
were still widely used for batch processing, and tape was also used for
backing up online transaction data. By the early 1970s, disk-to-tape backup
and restore utilities were a standard part of mainframe operating systems.

In 1973, IBM's San Jose labs made another breakthrough: The Model 3340
Winchester disk, a hermetically sealed hard drive with lightweight heads
that rode only 18 microinches above the disk surface, compared with 800
microinches for the RAMAC. The resulting higher capacity, faster
performance and lower cost made Winchester technology the new standard.

One company that adopted Winchester technology was Shugart Associates,
founded by onetime IBM hard-disk product manager Alan F. Shugart (who later
founded hard-disk giant Seagate Technology). By 1979, Shugart Associates
was attaching its hard drives to desktop computers using a
device-independent parallel connection called SASI, for Shugart Associates
Standard Interface. In 1982, SASI was renamed SCSI (Small Computer System
Interface) and eventually became a standard for connecting storage devices
to computers of all sizes.

Through the 1980s, system vendors continued to improve utilities for
migrating inactive online data to tape, consolidate unused storage space
and compact archived data. In 1988, researchers led by David A. Patterson
at the University of California, Berkeley, published their description of
redundant arrays of inexpensive disks, or RAID. Arrays of disk drives had
been used before to replace large, expensive disks, but Patterson's team
developed a complete architecture that would eventually become an industry
standard.
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