Posted by: Beth Pariseau
Hitachi GST says it anticipates that by the year 2011, it will be able to pack 4 TB of data onto a SATA drive and 1 TB of data onto a 1.8″ notebook hard drive.
The drive maker is basing these predictions on a new drive-head design, which it is unveiling at the 8th annual Perpendicular Magnetic Recording Conference this week in Japan.
The new design incorporates perpendicular recording, which places bits on end rather than side-by-side on disk to increase density, as well as the principle of Giant Magnetoresistance (GMR), a breakthrough in magnetic materials science that earned its discoverers the 2007 Nobel Prize in physics. Simply put, GMR refers to the fact that very thin films of metal can be highly sensitive to magnetic changes if the films are in the presence of a magnetic field. GMR was discovered in 1988 near-simultaneously by Albert Fert of the Université Paris-Sud in Orsay, France, and Peter Grünberg of the Forschungszentrum in Jülich, Germany; the two men share the Nobel this year.
GMR has led to advances in drive density since 1997, according to John Best, chief technologist of Hitachi GST. But, what the company is announcing today is a new twist on the magnetic field part of the equation — a concept called Current Perpendicular to the Plane, or CPP-GMR. The new Hitachi drive head design runs the electric current vertically through the drive head, allowing the current to pinpoint ever smaller areas of the disk surface. This will allow the head to read drive tracks as close together as 30 nanometers. Today’s densest drive tracks are 70 nm or greater; 30 nm would yield the 4 TB size Hitachi is projecting for a 3.5″ drive.
From here, however, the challenge will be consistently mass-producing both drive heads and drive platters at that density — and drive substrate materials will still need several more years to catch up. ”It’s one thing to demonstrate a few heads and another to efficiently mass-produce them with reliable yields,” said John Rydning, research manager for hard disk drives at IDC. “What you have to remember is that Moore’s law refers to certain characteristics of the semiconductor manufacturing process, and hard drives are already at the very forefront of semiconductor manufacturing technology.” It will take several years for drives to catch up to the capabilities of these new heads, he said.
And maybe it’s time to ask, how big can drives get? 1 TB SATA drives are already causing systems makers to rethink RAID; what will 4 TB drives mean in terms of reliability and data protection? It’s an unknown right now, Rydning said, but he predicted the advance will more commonly be used to make big drives physically smaller, rather than denser. “Think about it,” he said. “We don’t have 5 and a quarter-inch drive sizes anymore.