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.
Jumping to Jukeboxes
RAID wasn't the only change in the traditional disk-and-tape world of storage. By the late 1980s, write-once optical disks such as CD-ROMs had arrived; they were slower but more durable than tape and easier to access using automated jukebox systems.
In the 1990s, storage demands skyrocketed due to data warehouses, online analytical processing, multimedia and Internet applications. At the same time, while the speed of traditional directly attached storage connections such as SCSI and Fibre Channel had grown to 100MB/sec., network transfer rates for Gigabit Ethernet were even faster. In 1995, storage vendor EMC Corp. developed the concept of network-attached storage, in which storage devices could be accessed by any computer on a high-speed network.
Today, storage-area networks can include RAID arrays that back themselves up to tape automatically, automated jukeboxes of fast optical disks and tape cartridge servers, all connected by fast networks and controlled by storage management software.
And now, on with the story . . .
Cheap & Secure Data Stores
Stories in this report:
- Editor's Note: Cheap & Secure Data Stores
- Storage: The Story So Far
- Five cost-cutting strategies for data storage
- ATA drives: Cheap, but hurt by PC image
- SAN Security: Locking the data store
- Cloning Data for Disaster Recovery
- Tech Check: Backups Get Better
- Direct Access File System
- Storage virtualization: It?s promising but users are holding back
- How your career can thrive in the storage market
- The Next Chapter: Predictions on the future of data storage
- Stalking Storage ROI
- SANs are key to storage ROI, consultant says
- IP storage: More products coming in 2003
- Three Questions for EMC