Storage: The Story So Far

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.