IBM says it has made the world safe for magnetic storage as we know it for perhaps another five years, after breaking the world record for cramming data bits into a square inch of hard disk. Engineers at the company’s Almaden Research Center, San Jose, California have demonstrated reading and writing at realistic data rates against a drive carrying 20Gigabits of data per square inch. The company claims this density is three times greater than that of any product currently shipping and, IBM claims, will be ready for market itself within a conservative three-year timeframe.
Although the breakthrough is another opportunity for IBM to flex its storage muscles and kick sand at the R&D efforts of rivals (CI No 3,666), it will be greeted with quiet sighs of relief in many quarters of the storage business. Although disk densities have been increasing at better than 60% per year since 1991 (when IBM introduced its magnetoresistive sensor read technology) and driving the cost per GB down from $5,320 to $18.42 in the process, the industry is concerned that the absolute threshold for conventional magnetic storage density might be only a few years away. When it comes, says Robert Scranton, IBM’s director of recording head technology at Almaden, it will precipitate a fundamental change for the whole business. Now though, he says, that day has been comfortably postponed for five or more years.
IBM is keeping the lid on the technical details of its achievement until the Intermag 99 International Magnetics Conference in Kyongju, Japan, next week. However, the company revealed that its demonstration involved an advanced version of its giant magneto-resistive read head, a narrow-track thin-film inductive write head, ultra-low noise cobalt-alloy magnetic media and advanced partial-response, maximum likelihood (PRML) channel electronics. This system performed read and writes at 18 Mbytes per second, recording an uncorrected error rate of less than 100 million bits.
One of the basic problems IBM seems to have solved in its latest demonstration is the tendency for the magnetic performance of individual particles in storage media or its grains to become unstable as density increases. Already, said Scranton, some products are being shipped which exhibit worryingly high decay of magnetic performance at room temperature. Although these products work, their potential to support increased data density in future is borderline said Scranton. The new IBM technology exhibits a thermal decay characteristic of less than 1% of magnetic signal amplitude, he said, suggesting that there could be room for greater density in future – possibly up to 40GB or beyond.
To get to 40GB, IBM now believes it may be possible to keep tweaking the various technologies which contribute to conventional disk drive systems. However at some point, which will arrive suddenly, like a cliff said Scranton, more dramatic changes will have to be made to keep storage densities increasing at present rates. After five years, for instance, Scranton envisages moving to new media materials with larger grains, and changing the density of grains to bits from today’s level of 1,000 grains per bit, to a 1 bit:1 grain ratio. This development will be inconvenient for the storage business, involving a move to radically different materials, but it would preserve the usefulness of most other storage technologies since the bigger grains will be magnetically more stable.
Elsewhere, particularly in Japan, great efforts have been expended on increasing disk densities by moving to a perpendicular model for storing bits on media – essentially replacing today’s two-dimensional longitudinal approach, with a 3D vertical approach. However, these efforts have produced little in the way of practical results, and Scranton believes more could be achieved if the same effort and research and development is expended on existing technologies. In this way the storage world can remain a flat world, for the short to medium term benefit of all concerned
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