May 2, 2006. Copyright 2006, Graphic News. All rights reserved

Disk drive designers look up for extra space
By Mark Rutter

LONDON, May 2, Graphic News:  When the first commercial hard disk drive was introduced in 1956, nobody could have predicted the exponential growth in capacity that would occur over the next 50 years. Growth reached a peak in the last decade, when the average hard disk doubled in size every year, allowing us to store thousands of our favourite songs and images on a single MP3 player or handheld PC. Now it looks like the end is in sight for existing technology as constraints on further expansion in capacity are forcing engineers to rethink the design of hard disks.
 
Hard drives store information by magnetising tiny sectors on a disk, so that each has a north and south pole. Traditionally, the sectors are lined up end to end, orientated in the direction in which the disk spins -- so called longitudinal recording. If however, the sectors are too close, they interfere with one another in a phenomenon known as superparamagnetism. The sectors become incapable of retaining their correct magnetic charge, resulting in corrupt data. Over the years, disk drive manufacturers have been able to increase the amount of information held by packing these sectors closer together, using various innovations to avoid superparamagnetism. But, the consensus now is that we are near the physical limit for longitudinal storage.
 
With hardware designers looking to pack in more information on to physically smaller disks, they are now doing what town planners have done for decades: creating more space by building upwards. Perpendicular recording uses magnetised sectors lined up side-by-side with their north and south poles pointing up or down in relation to the direction in which the disk spins. By turning the sectors on their ends, more can be crammed on to a disk before individual sectors start to react to each other. The technique has been around for over a century, when it was used to record sound, although modern work on perpendicular recording began in Japan in the mid 1970s.
 
Industry specialists are estimating that perpendicular recording technology could see hard disk capacity increase tenfold over the next five years. There is already evidence that the advance has started. Currently nearly all hard disk drives for PCs rely on longitudinal technology, with entry-level machines generally having less than 200 gigabytes of storage. Seagate, the worldÕs largest manufacturer of disk drives, has just released a 3.5 inch 750 gigabyte perpendicular hard drive for PCs, and has more cutting edge products in the pipeline. Another early mover in the perpendicular hard drive market is the Japanese electronics company Hitachi.
 
New disk-hungry applications, such as recording high definition television images, will force the pace of production of even higher capacity hard disk drives, able to store thousands of gigabytes -- or terabytes -- of information. Added to this is the push for physically smaller hard disks to service the demand for more miniaturised personal electronic products. Although perpendicular recording technology should satisfy this demand over the next few years, disk manufacturers are already starting to look towards the next generation of information storage devices.
/ENDS