Hitachi Predicts 4 TB Disk Drives by 2011
October 22, 2007 Timothy Prickett Morgan
The clever engineers at the former IBM disk drive business that is now known as Hitachi Global Storage Technologies are pushing the technology barriers again, and said last week they have shrunk the read/write heads on a prototype disk drive enough that the company is predicting it can ship 4 TB disk drives by 2011 for the desktop market, and presumably for the server market soon thereafter.
To boost the recording density of its disk designs, Hitachi’s San Jose Research Center in California and Central Research Laboratory in Japan figured out a way to reduce the size of the disk heads by a factor of two. The technology should allow Hitachi to create disk heads that are in the range of 30 nanometers to 50 nanometers in width. The future disk heads are based on a perpendicular recording technique originally invented by IBM. The new technique uses disks that have current perpendicular to the plane giant magnetoresistive (CPP-GMR) heads, which yield a recording density of between 500 gigabits per square inch to 1 terabit per square inch. That top-end number is four times the current data recording density of the most dense, 1 TB disk drives, which from Hitachi have an areal density of 148 gigabits per square inch. (It gets to 1 TB by having lots of platters.) Hitachi’s most dense disks weigh in at around 200 gigabits per square inch. These disks use a disk head technology called tunnel magnetoresistive (TMR), which has a 70 nanometer track width for the disk head and which starts to produce read and write errors on disk platters with data densities of more than 500 gigabits per square inch. So clearly, Hitachi had to come up with a new disk head to get more data stored on the disk.
Hitachi says that disk recording heads with 50 nanometer track widths should come out of its factories in 2009, followed by heads with 30 nanometer track widths by 2011.
GMR technology is a hot topic these days, since Albert Fert, of the Université Paris-Sud in France and Peter Grunberg of the Institute of Solid State Research in Germany won the Nobel Prize for Physics for discovering the GMR effect in 1988. GMR arranges layers of iron and chromium in the disk head in such a way that quantum effects allow a tiny change in a magnetic field (in the case of a disk drive head passing over a disk platter with magnetically encoded data) to cause a big change electrical resistance (and therefore a signal coming off the disk drive head and out to the disk controller) to allow very high data densities on that device. In 1997, IBM’s disk unit figured out how to commercialize GMR, and brought very dense disks to market, getting a substantial leads on rivals.