IBM sets another disk-drive world record

35.3 billion bits per square inch with product-stable disk material

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SAN JOSE, Calif - 04 Oct 1999: -- IBM has set a new computer data storage world-record of 35.3 billion data bits per square inch on a magnetic hard disk -- a 75 percent increase over the 20-billion-bit milestone the company achieved less than five months ago.

This new record is expected to lead to disk drives that could store three times more information than those available today.

"This demonstration underscores both IBM's technology leadership in the magnetic hard-disk-drive industry, and also our confidence that we will continue to be able to provide our customers with the increasing data-storage capacities they need to take full advantage of new data-intensive applications in e-business and deep computing," said John Best, Vice President of Technology, IBM Storage Systems Division.

The most significant feature in IBM's latest achievement is the new magnetic "media" -- the metal-alloy materials that coat the hard-disk platters and where the data is stored. Particularly important, this proprietary magnetic material exhibits product-quality stability, not the data-robbing fluctuations that had been feared to be present at such high densities.

Data is written onto the media as a pattern of bits -- tiny oblong regions magnetized in either of two opposite directions. If bits can be made smaller, more data can be stored within the same disk area. But if the bits become too small, they may not be able to maintain their magnetic orientations for the many years required for commercial products.

One of several ways to forestall this "superparamagnetic effect" is to use a magnetic material that more strongly resists magnetization changes. But, paradoxically, it must also still be easy to erase and re-write when needed. IBM's new magnetic media has both of these desirable properties. The test bits were as stable as those in products today. Best says the proprietary disk media can be manufactured commercially using existing production equipment. Lab results also suggest that even smaller bits on this media will continue to be stable, enabling a clear path to even higher areal densities in the future.

At 35-gigabit density, every square inch of disk space could hold 4.375 gigabytes -- nearly as much data as a 4.7-inch (120mm) diameter DVD-ROM. (4.7 gigabytes per surface) or seven CD-ROMs (each 650 megabytes). At this record density, a single desktop drive platter (3.5-inch diameter) would hold nearly 50 gigabytes; a notebook platter (2.5-inch) more than 20 gigabytes and a microdrive (1-inch) more than 2 gigabytes.

Because fewer disks are needed to achieve a given data-storage capacity, increasing data density leads to disk drives that are lighter and consume less energy -- important factors in portable computers -- and tend to be more reliable.

Since 1991, when IBM introduced the industry's first magnetoresistive (MR) sensor for reading data on hard disks, data density has increased at greater than 60 percent a year and have doubled in each of the last two years. If this trend continues, 35-gigabit-density products would be available within a few years. This summer, IBM began shipping products with data densities as high as 10.1 gigabits per square inch.

The 35-gigabit density milestone was achieved by a team of scientists and engineers from IBM's Storage Systems Division, which develops, manufactures and sells data-storage products. This demonstration is part of its long-standing collaboration with IBM Research to understand and advance magnetic data storage technologies.

Technical details:

The 35-gigabit demonstration used an advanced version of the giant magnetoresistive (GMR) read head -- the most sensitive sensor for reading magnetic bits on disks -- a narrow-track thin-film inductive write head and advanced PRML (Partial-Response, Maximum Likelihood) channel electronics. Some 522,000 bits per inch were written along the concentric tracks packed at a density of 67,300 per radial inch with an off-track capability of 15 percent of the track pitch.

The bits were written and read at data rates of 18 million bytes per second. The on-track data was read essentially flawlessly, with an uncorrected rate of less than one error in a 100 million bits, which in products would be reduced by error-correcting codes to less than one in a trillion. The latter figure is equivalent to transcribing more than 1,000 years of a daily newspaper before making a single error.

The Storage Systems Division is a unit of the IBM Technology Group, a major supplier of components to computer makers. IBM is one of the world's largest manufacturers of hard drives, liquid crystal displays, tape storage systems and semiconductors.

The IBM home page is at: For more information about IBM hard-disk drives, see .

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At 35-gigabit-per-square-inch density, each square inch of disk space could hold:

Three hours and 15 minutes of MPEG-2 compressed video, approximately equal to two full-length movies.

More than three days of MP3 compressed audio (77 hours = 3.2 days at 56.67 MB per hour).

The text from 2,187,5000 sheets of double-spaced typewritten paper, which would make a stack 730 feet (222 meters) high, about the height of a 50-60-story building. Laid end-to-end, the paper would stretch some 380 miles (611 kilometers), which is farther than the distance from San Francisco to Los Angeles (344 miles) and nearly that of from Boston to Washington D.C. (394 miles).

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