Shaken, not stirred

SCIENCE & TECHNOLOGY

Data storage

Feb 10th 2005
From The Economist print edition

The answer to slow data retrieval may be to shake the system up

COMPUTER processors may be getting faster and faster but the time it takes to retrieve data from a computer's hard disk is still a bottleneck. That rate depends on the speed at which the disk is spinning, which in turn determines how quickly a given bit of data arrives under the reading head that is responsible for detecting it and transmitting it to the rest of the machine.

Modern hard disks spin at between 5,400 and 15,000 revolutions per minute (rpm). If they went much faster than that, the forces generated would cause them to shatter. For years, this has seemed an insuperable problem, and the industry has been waiting for solid-state memory, which has no moving parts, to become cheap enough to do the job instead. But Dataslide, a firm based in Sussex, Britain, believes it has a revolutionary solution to the retrieval problem that does not require waiting for solid-state mass memory—or, rather, it has a non-revolutionary one.

Dataslide proposes to abandon rotation in favour of vibration. Charles Barnes, the head of Dataslide and inventor of the vibrating drive, has produced a prototype drive containing a rectangular plate coated with magnetic-storage material similar to that used in disk drives. A second plate above it carries an array of heads that have been lithographed on to its surface using the technique employed to make the pixels of liquid-crystal display screens. The plates themselves are made of titanium silicate glass, an extremely strong material, and covered with low-friction diamond coatings which act as a lubricant. That is because, instead of spinning under the heads, the lower plate vibrates from side to side under them 600 times a second.

The upshot is that every spot on the lower plate passes under a reading head every 833 nanoseconds (a nanosecond is a billionth of a second). The average time required to read a given bit of data is therefore 417 nanoseconds—or about ten times faster than a disk spinning at 15,000rpm. And that, Mr Barnes hopes, is only the start. He believes that with currently available materials and technology it should be possible to increase the frequency of vibration to 100,000 times a second, equivalent to a disk rotating at 12m rpm.

For the moment, the company's goals are more modest—within 18 months it hopes to build a drive with 64 heads storing up to 72 gigabytes. Mr Barnes believes it will eventually be possible to make drives with over 1m heads. These would be capable of storing vast amounts of data and handling them at rates of up to 300 gigabytes a second—hundreds of times faster than the rates that are currently attainable.

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