History (1999): Komag/HMT/Read-Rite Reached 25GB Per Square Inch on One 3.5-Inch Magnetic Disk Platter

Until now, the demonstration record for areal density on a 3.5-inch magnetic disk platter was held by the duo HMT/Read-Rite, with 20.0GB per square inch. Now it’s the trio Komag/ HMT/Read-Rite that have just demonstrated 26.5GB per square inch, as well as Seagate with 23.8GB per square inch, or more than 2x the density of current disks.

Komag’s new record with Read-Rite translates to roughly 38GB per 3.5-inch platter, and Komag expects “the industry will require disks of this density by the end of 2001 at the current rate of growth.”

For this demo, the disks were manufactured by Komag on current-gen media with alloy system, in-line sputtering machines, as well as by HMT, with an advanced ultra-low noise, ultra smooth media with 2,500Oe coercivity and an Mrt of 0.40 memu/cm2.

Marvell Semiconductor provided a trellis-coded noise predictive read channel, model 88C4200.

Read-Rite furnished advanced GMR heads.

Data rates of 29 to 62MB/s were achieved with a read sensitivity of 6.5 millivolts. Linear density was 504,000bpi and track density 52,600tpi. The ontrack error rate was less than one error in over one billion bits read with over 18% off-track capability.

“We anticipate this innovation design can be extended to 40 billion bits per square inch,” said Dr. Subrata Dey, VP, advanced technologies, Read-Rite.

Dr. Michael A. Russak, VP R&D, and CTO, HMT, goes even further: “In depth analysis of the relationship between media microstructure and magnetic recording performance provides the insight required to push magnetic recording beyond 100Gb per square inch.”

The 23.8Gb per square inch achieved by Seagate Technology corresponds to 32GB per platter.

A few parameters of the demonstration: 45,800tpi, 520,000bpi, 19.8MB/s transfer rate, distance between the head and media of .0254p, error rate on tracks less than one error per 10 million bits read.

This article is an abstract of news published on issue 140 on September 1999 from the former paper version of Computer Data Storage Newsletter.