Storage Adviser | Mario Apicella » Fujitsu moving toward terabit per square inch drives

November 29, 2006 | Comments: (0)

Fujitsu moving toward terabit per square inch drives

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It's a rather cautious press release this one from Fujitsu, and the technology is not ripe yet for production, but if it evolves as planned we should see some very fat, hybrid disk drives in a not too distant future.

The breakthrough trumpeted by Fujitsu is the making of a multi-layered optical element, essentially a new recording surface to be used with thermal assisted magnetic recording.

Sounds like Greek? (Apologies to my Hellenic friends). Perhaps I should start by saying that there is a general agreement among researchers: Magnetic recording will stop short of reaching the holy grail density of 1 terabit per square inch.

Why? Because increased density calls for a finer grain of the recording surface, which, unfortunately makes the medium forgetful. Yes, forgetful, because a finer grain makes worse a phenomenon called thermal decay: recorded bits slowly lose their magnetic field and become unreadable.

Obviously not good, but does perpendicular recording have the same problem? Unfortunately yes, which is why researchers are exploring new technologies, thermally assisted magnetic recording (TAMR), for example.

How does TAMR work? BTW some call the technology OPTICALLY assisted magnetic recording or hybrid recording. I like the last expression and not only because it's shorter but because conveys immediately the basic concept: TAMR is a combination of magnetic and optical recording.

Here is the quick take on TAMR: During recording, a light beam heats the medium above the Curie point. Once the bits are written a cooling process brings the temperature down again.

Why the temperature roller coaster? Because this makes bits recorded on high density, finer grain media more stable at normal temperature, offsetting or diminishing the thermal decay effect.

Obviously TAMR requires a different recording head with both optical and magnetic capability, but also a different recording medium than what current commercial drives have.

Which brings me back to the announcement from Fujitsu and their multi-layered optical element. Fujitsu claims that:

engineers were able to achieve a sub-hundred nanometer (nm) optical spot size, which is considered an enabling element for the successful deployment of one terabit per square inch recording technology for hard disk drives

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So what happens of perpendicular recording, is that another dead technology? Not quite, according to Fujitsu:

The merging of optical thermal assist and perpendicular recording is of high interest to the hard disk drive industry, as it enables manufacturers to reach capacities around ten times greater than what is now possible

Sounds promising.

Posted by Mario Apicella on November 29, 2006 08:06 AM

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