Analysis

posted on 07 August 2008 08:54

Hitachi GST will tunnel ahead to increase hard drive capacity and then enter the land of giants with GMR heads in thre or four years' time.

The firm has said it hoped to achieve a TB drive in the 2010 period but yesterday and puzzlingly was reported as saying it hoped to achieve half that capacity or 2.5 times current 1TB drive capacity with existing technology in the 2010 timeframe.

A Hitachi GST spokesperson said: "The 2.5x increase you referenced is achieved using conventional TMR head technology. CPP-GMR is a more advanced technology and harder to implement, but if successful, has the potential to deliver recording densities of 500 gigabits per square inch to one terabit per square inch, as previously reported."

"Based on our current experience with TMR, it appears the technology will continue to be used for a longer period of time than originally thought. As a general rule, HDD industry suppliers will always try to extend current technology as long as possible."

Very recently Hitachi GST was reported as saying it could extend the use of TMR (Tunnel Magneto-Resistive) heads beyond a previous limit of 500GBit/sq in areal density to the 610-635Gbit/sq in level by using a wrap around shield (WAS) to prevent the head's own magnetic forces corrupting perpendicularly recorded data on adjacent tracks to the read track.

This would enable narrower tracks, increased areal density and higher-capacity hard disk drives (HDD), 2.5 times more capacity than with today's 250Gbit/sq in  which gives us 3-platter, 1TB, 3.5-inch drives. Product would arrive in the 2010/11 timeframe.

Next there would be a new generation of read/write heads using CPP-GMR (Current-Perpendicular-to-Plane Giant Magneto-Resistance) heads which would enable terabit areal densities still using perpendicularly recorded data. This technology is described here. The timeframe for a new Hitachi GST head technology is generally two to three years after the previous technology, which means a 2013 or so arrival date for 5TB, 3-platter, 3-5-inch drives with 1,00Gbit/sq in or so areal density.

It will be interesting to calibrate this view with the HDD technology future as seen by other HDD manufacturers.

^{[Chris Mellor.]}