PMR: Perpendicular Magnetic Recording
Source: Hitachi.
Toshiba's 1.8" hard drive family features capacities up to 60 GB, and was the first commercially available hard drive product to use Perpendicular Magnetic Recording (PMR). This technology aligns the magnetic elements vertically, as opposed to conventional longitudinal recording (see the image above). This in turn allows the drive to store more bits per square inch; with older recording methods, increased data density would result in magnetic particles interfering with each other due to the so-called superparamagnetism effect, which compromises data integrity.
Data densities have now reached slightly above 100 gigabits per square inch, and are expected to at least double again due to perpendicular recording. Drive manufacturers hope to increase data density tenfold over the next few years!
Since this technique is clearly the future of recording, all manufacturers are working on PMR-based hard drive products. Hitachi expects terabyte 3.5" hard drives and 20 GB micro drives as early as 2007, and Fujitsu has already announced a 200 GB 2.5" notebook hard drive for 2H 2006. However, thus far, only Toshiba and Seagate have released PMR products to the market: Toshiba dominates the 1.8" drive segment, while Seagate is shipping its 2.5" Momentus 5400.3. The most recent PMR product is Seagate's Cheetah 15K.5 enterprise-class hard drive. In addition to these, it is rumored that Seagate will deliver a 750 GB desktop drive by this summer. We would not be surprised to see the first terabyte hard drive announcement by the end of this year.
