In the race to increase the areal density of HDDs the tech to work towards is currently Heat Assisted Magnetic Recording as the current shingle technique has helped us increase storage capacity by a small amount but not enough to be the next evolution.  Seagate announced their strategy to develop HAMR technology over a year ago but we have yet to see a prototype.  Western Digital has just shown off their version of HAMR to a bevvy of journalists, not including The Register, with a working prototype.  WD predicts densities reaching 4 terabits per square inch, making an 8TB 2.5" drive a possibility but they have not predicted a release date yet.

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"In September 2012, Seagate boss Steve Luczo gave a presentation using a HAMR technology disk drive. Now, more than a year later, a WD exec has done the same with the company's own HAMR tech drive."

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