Simply changing the pattern by which data is recorded may lead to increased hard drive capacities, study finds

Apr 10, 2013
Data storage: Shingled tracks stack up
By writing data on adjacent overlapping tracks, just as the shingles overlap on this roof, the shingled magnetic recording approach promises to increase hard drive capacities. Credit: iStockphoto/Thinkstock

Modern hard drive technology is reaching its limits. Engineers have increased data-storage capacities by reducing the widths of the narrow tracks of magnetic material that record data inside a hard drive. Narrowing these tracks has required a concordant reduction in the size of the magnetic write head—the device used to create them. However, it is physically difficult to reduce the size of write heads any further. Kim Keng Teo and co-workers at the A*STAR Data Storage Institute, Singapore, and the Niigata Institute of Technology, Japan, have recently performed an analysis that highlights the promise of an alternative approach, which may sidestep this problem completely.

In a conventional hard drive, a write head stores data by applying a magnetic field to a series of parallel, non-overlapping tracks. Halving the width of the track effectively doubles the data-, but also requires the size of the write head to be halved. The head therefore produces less than is needed to enable stable data storage. This is because the small magnetic grains that are characteristic of modern hard drive media need to be thermally stable at room temperature.

Shingled represents a step towards solving this problem as it allows for narrower track widths without smaller write heads. Rather than writing to non-overlapping tracks, the approach overlaps tracks just as shingles on a roof overlap (see image). Tracks are written in a so-called 'raster' pattern, with new data written to one side only of the last-written track.

Teo and co-workers analyzed the scaling behavior of this approach by using both numerical analysis and . Their results showed that the size of the data track is not limited by the size of the write head, as in conventional hard drives. Instead, the track size is limited by the size of the magnetic read head, and by the 'erase bandwidth', which represents the portion of the track edge that is affected by adjacent tracks.

"This is a paradigm shift for the industry," says Teo. "A relatively small difference in the way that writing occurs calls for a completely new approach to head design." Teo expects the shingled approach to be a useful stop-gap measure prior to the arrival of more advanced, next-generation technologies in the next decade or so that will apply more radical modifications to the hard drive such as the use of heat to assist the write head.

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More information: Teo, K. et al. Analysis and design of shingled magnetic recording systems. Journal of Applied Physics 111, 07B716 (2012). jap.aip.org/resource/1/japiau/v111/i7/p07B716_s1

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Lurker2358
1.3 / 5 (3) Apr 10, 2013
This reminds me of playing "SimCity" on the SNES. Because of the mechanics of the game, Residential and Commercial districts could partner with an adjacent square of the same type to make larger, more efficient structures.

Well, there was a bug in the game, which allowed you to bulldoze 1/3rd of a district, without destroying it's value, and thereby stack districts over-lapping by 1/3rd. If you did it right you could accomplish it without losing the pairing for the highest level structure. This allowed population growth much larger than what was supposed to be possible.

Well, I hope it works, but I'm wondering what de-fragmenting that HD will look like, and how stable it is, and how many writes you get before it becomes unstable. SimCity got out of hand after about 800k to a 1000k population...
EyeNStein
1 / 5 (3) Apr 10, 2013
By using a byte (8x) wide write/read head and skewing adjacent tracks to avoid crosstalk even greater data densities could be achieved. And the 8x speed improvement of byte writing could be useful too!
rah
1 / 5 (1) Apr 11, 2013
...or it may not.

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