Standing bits on end, for example, requires the use of a soft underlayer; this layer, which guides the magnetic flux from the drive’s read-write head as bits pass below it, makes the head more efficient, which means it can use a stronger magnetic field, which, in turn, means the grains can be made from a magnetically “stronger” material that’s less vulnerable to the superparamagnetic effect.
Perpendicular magnetic recording has been a long time coming – in part, because it involves arranging new materials in tricky new configurations, and in part because manufacturers wanted to test the technology thoroughly before putting it in front of consumers. “When you introduce perpendicular recording there is a fairly significant change in the material structure of the disk,” explains Best. “There’s a soft underlayer which carries the current from the read/write head, and a media layer on top, and when you introduce these materials you have to worry about things like surface roughness and susceptibility to corrosion from humidity. We built over 20,000 drives and put 5,000 of them into extended reliability tests before we even shipped the product. We wanted to make sure it was super-reliable.”
“Perpendicular recording is not an easy technology to bring to market,” confirms Maciek Brzeski, vice president of marketing for Toshiba’s Storage Device Division. “All of the prior technological improvements on hard drives have been somewhat incremental. But with perpendicular recording, it’s not a slam dunk. It takes some time and persistence.”
Manufacturers estimate that perpendicular recording will allow them to keep shrinking bits until hard drives reach 500 gigabytes, or perhaps 1,000 gigabytes (one terabyte). Eventually, however, the superparamagnetic effect will come back into play. “It’s just bought us a little bit of time – a few generations of hard drive models – and then we get into the same problem,” says Best. He says Hitachi is already studying “patterned media” –the idea of arranging individual grains in specific patterns to reinforce their magnetic stability–as a way to break the 1-terabyte barrier.
Toshiba will begin mass production of its 2.5-inch drive in August, and expects to see them in high-end consumer laptops in 2007. Hitachi says its 160-gigabyte, 2.5-inch drive will show up in a broader range of laptops; it plans to release a 1.8-inch drive for handheld devices next year.
Auspiciously for manufacturers, the new perpendicular-recording drives are arriving at just the moment when digital video – which consumes large amounts of disk space – is booming. Consumers can now use their computers to download network TV shows from iTunes, YouTube, Google Video, and other sources; to record directly from cable or satellite connections, as TiVo and other digital video recorders do; and to upload video they’ve captured themselves on the newest digital video cams, which can eat up 15 gigabytes of space per hour of video.
“For years we’ve dreamed about the consumer applications starting to provide the growth engine for hard drives, and now it’s actually here,” says Hitachi’s Best. “So it’s a pretty exciting time.”