Disk Drives, Please Stand Up

Seagate's latest notebook hard drive, unveiled last month, boasted a capacity of 160 gigabytes. That's impressive for a laptop, sure, but what really made the drive a standout was its underlying technology: perpendicular recording.

During the next two years, that system of reading and recording data will prevail over the current standard of longitudinal recording, opening doors for OEMs and systems builders alike.

In disk drives that use longitudinal-recording technology, the data is stored horizontally and squeezed together until space runs out. With perpendicular systems, bits of data are aligned vertically to increase areal densities.

The latter technology will enable manufacturers to build higher-capacity drives into notebooks. In 2004, drives of 80 Gbytes or more accounted for 10 percent of laptop disk drives, says Joni Clark, SATA marketing manager at Seagate. In 2005, that number jumped to 40 percent, and it's expected to reach 80 percent in 2006, she says.

"For longitudinal recording to reach those capacities, you would have to add another platter and more heads, and that's just not feasible--it's no longer a notebook drive," Clark says. "With the growth and capacity changes, perpendicular [recording] seemed like a good fit."

In addition to boosting capacity, perpendicular recording offers improved performance without increasing the disk's spin speed by enabling more bits of data to pass under the drive head in the same amount of time.

Seagate's new Momentus 5400.3, the first drive based on perpendicular-recording technology to hit the market, spins at 5,400 revolutions per minute (RPM) and has fewer disk heads than longitudinal systems. And because it has fewer moving parts, it requires less power as well. The 5400.3's areal density is 132 Gbytes per square inch, vs. 91.5 Gbytes psi for its predecessor, which is based on longitudinal technology.

"This is our workhorse. It's targeted at mainstream notebooks, tablet PCs and copiers," Clark says. "Perpendicular [technology] changes the entire dynamic of the hard drive. It's the replacement recording technology going forward."

Seagate isn't the only vendor making that prediction. Others--Fujitsu, Hitachi and Maxtor included--are just taking a little more time to unveil their products.

Last year, Hitachi Global Storage Technology demonstrated a prototype perpendicular drive with double the areal density of the vendor's highest-capacity longitudinal drives. At the time, Hitachi said it expected to offer disks with areal densities of 230 Gbytes psi in 2007.

John Best, chief technologist at Hitachi, says trying to beat Seagate to market was never the hardware vendor's goal. Company employees have used notebooks with perpendicular drives for more than a year now, he says, adding that the goal is to ensure the reliability of those drives before bringing them to market.

"We're making sure that with perpendicular drives--because they're based on a new structure--we really understand any potential liabilities," Best says.

Maxtor, too, plans to take a more gradual approach to unveiling drives using perpendicular technology. But the transition is inevitable at some point, according to Marty Czekalski, the vendor's interface architecture initiatives manager.

"Without the evolution to perpendicular [technology], you'd be hitting a wall," he says. "But it won't mean a large shift in the overall trends."

As it turns out, 2.5-inch drives--prevalent in notebooks and blade servers--will offer the key value proposition in this space, at least for the short term. In those fast-growing form factors, space is limited, and perpendicular recording will allow manufacturers to do more with less.

Meanwhile, systems builders and OEMs will be able to do the same, extending the storage capacities they support within the footprints they offer.

"Perpendicular recording is what will allow us to offer fairly dense drives," says Bob Moore, Hewlett-Packard's group product marketing manager for industry-standard servers. "We see that becoming more prevalent into 2006."

Some agree with Maxtor's Czekalski, proposing that there's still a decent amount of space to be wrung from longitudinal drives and that the transition to perpendicular technology will be a more gradual one. "We'll ship perpendicular drives when the quality and the price points are where they need to be," says Hubbert Smith, director of enterprise marketing at Western Digital.