By Ann Silverthorn
—Perpendicular magnetic recording has emerged as an answer to a leveling off in the density of data that can be stored on hard drives with traditional longitudinal recording. So far, perpendicular drives for notebooks and consumer electronics devices are available, and perpendicular drives for enterprise storage could emerge by year-end.
To achieve higher levels of areal density (usually expressed as the amount of data that can be placed in a square inch on a disk), drive manufacturers place bits perpendicular to the disk platter, rather than laying them flat as in longitudinal recording. In longitudinal recording the bits can be shrunken, but the smaller they are the more susceptible they are to erasure from thermal heat.
"Perpendicular recording reorients the bits so that you can get more bits per unit of area, but they are more stable," explains John Rydning, research manager for hard disk drives at International Data Corp. (IDC)
"In 2005, our research revealed that about 40% of the 2.5-inch drives shipped were 80GB and above. In 2006, it will be 60%," says Joni Clark, a product marketing manager at Seagate. "Because increases in areal density for longitudinal recording have slowed down, we can't jump the capacity points like we used to. So when we looked at the capacity requirements of 2.5-inch drives we realized that longitudinal wasn't going to be the technology to achieve these capacity points."
Seagate, Toshiba, Fujitsu, and Hitachi have all made perpendicular recording announcements in the past year. Toshiba brought a 1.8-inch 40GB perpendicular drive to market in August 2005, followed by a dual-platter 80GB drive earlier this month. Seagate introduced its 2.5-inch Momentus 5400.3 drives today, with up to 160GB on a single platter. Fujitsu plans to ship 2.5-inch 200GB drives with perpendicular recording in 2007, and Hitachi forecasts a 1TB 3.5-inch drive for release in 2007.
Specs on Seagate's 2.5-inch Momentus 5400.3 drives include a rotation rate of 5,400rpm, 132 gigabits per square inch, and a 100MBps Ultra ATA interface. Versions with 1.5Gbps Serial ATA (SATA) interfaces are due later this year.
Seagate also plans to migrate its 7,200rpm Momentus drives, as well as its 1-inch and 3.5-inch drives, to perpendicular recording.