The Channel

Tosh builds mega dense hard drive - but can't read it yet

We're halfway there...


Toshiba has announced a breakthrough in extending disk drive capacity - sort of. It can build a platter holding four times more data bits, but it can't read it.

The company has been developing bit-patterned media (BPM), a technique to make smaller collections of the grains used to record the magnetic charge for each bit and lay them out precisely on the drive, with an insulating ring around them to make them hold their magnetic state more reliably. Tosh has achieved, it says, a 2.5Tbit/in2 areal density, using magnetic dots 17nm in size, but has only managed to detect tracks on the prototype media, and is not yet being able to read or write individual bits. This points to a read/write head technology problem.

The read/write head has to detect and follow tracks and then read and write the bits in the tracks. There needs to be a head servo pattern for this as well as a data bit pattern. Tosh says its demonstration of track detecting and following on a BPM disk is a world first and a breakthrough. Yes, indeed, but sadly it's not enough.

The news was disclosed at the Magnetic Recording Conference in San Diego. Toshiba's highest areal density in a shipping dive is 541Gbit/in2 in its MK7559GSXP 2.5-inch hard disk drive. A quadrupling of areal density would take its capacity up from 750GB to 3TB. An equivalent jump in 3.5-inch HDD capacity would see a leap to an 8TB drive.

It suggests it could get the dot size down to 10nm and the areal density doubled to 5Tbit/in2. The company thinks that it might be able to ship a BPM HDD in 2013.


Seagate has been steadily researching heat-assisted magnetic recording (HAMR) in which data bits are made more resistant to changing their magnetic charge, again increasing storage reliability as bits get smaller, and need a flash of laser-sourced heat to be written to.

It is being anticipated that a transition to either BPM or HAMR would involve the HDD manufacturers in huge outlays of money. Making BPM media involves etching a gold master platter at the nanometre level and then imprinting platter surfaces with the etched pattern using product machinery that is still in development from suppliers such as Intevac, Molecular Imprints and Obducat.

The entire HDD supply chain of production and test equipment and components would collectively be spending colossal sums on the transition.

Head manufacturer TDK has demonstrated a HAMR-based head but not a BPM one, indicative perhaps of Toshiba's head-related difficulties. Tosh has been working on Nano Contact Magneto-Resistive (NCMR) head technology but this is clearly not at the same level of development as the media.

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