Hitachi Global Storage Technologies is announcing new advancements to a 100-year-old magnetic recording technology that will set the stage for ultra-high capacities such as a 20GB (gigabyte) Microdrive or a one terabyte 3.5-inch hard drive.
To achieve this, Hitachi has demonstrated the industry's highest data density at 230 gigabits per square inch (Gb/in2) on perpendicular recording. Hitachi believes 230 Gb/in2, which represents a doubling of today's highest longitudinal recording densities, will be implemented in commercial hard drive products in 2007. When fully realized over the next 5-7 years, perpendicular recording could enable a 10-fold increase in data densities over longitudinal recording.
Perpendicular recording has its roots in the late 19th century work of Danish scientist Valdemar Poulsen, who is generally considered the first person to magnetically record sound using this technique. The technology gets its name from the vertical alignment of data bits on the plane of the disk, which takes less room in contrast to the horizontal orientation of today's longitudinal recording technology. To be accurately recorded and read, the more closely-packed perpendicular bits also require a closer association between the read/write head and the recording media. Hitachi achieved the 230 Gb/in2 density by manipulating the head and media so that the distance between them is only 10 nanometers or 1/10,000th of a human hair.
While the hard drive industry has been using longitudinal recording successfully for five decades, it is now within two product generations of reaching its practical limit. Researchers are finding that longitudinal recording is losing its ability to maintain data integrity at areal densities much beyond 120 Gb/in2.
Hitachi is running a field test program and testers are using notebook systems from various manufacturers with the Hitachi Travelstar 2.5-inch drive. The data collected from this program will help Hitachi prepare for the eventual full-scale production of perpendicular recording hard drives. Hitachi expects to ship its first perpendicular recording product in 2005 on a 2.5-inch hard drive, used in notebook computers and handheld consumer electronics.
The company says that with longitudinal recording, the hard drive industry is quickly approaching a physical barrier called the "superparamagnetic limit," which occurs when the microscopic magnetic grains on the disk become so tiny that they are not strong enough to resist the various factors tending to demagnetize them. The result is that, over several years, the information written onto these magnetic grains can fade and become corrupted, rendering the storage device unreliable and unusable. Simplistically, the data bits can be thought of as little dominoes. Longitudinal recording, as its name indicates, lays these dominoes (data bits) horizontally, taking up more space. In contrast, perpendicular recording sets up the dominoes on their edges, allowing more bits per square inch of disk surface, resulting in higher storage capacity overall.