Seagate is finally offering its biggest hard drive yet — a staggering 32TB in a single drive, made possible by technology that uses lasers to heat and cool tiny sections of the platter in nanoseconds …
Seagate has been working on heat-assisted magnetic recording (HAMR) technology for 17 years and announced last year that it had finally developed it. Mozaic 3+ 32TB drives are now in mass production and will be available soon.
The company explains the problem of trying to squeeze more and more data onto a disk platter.
To increase the capacity of a hard drive, engineers try to fit more bits of data, or “grains,” onto each disk platter—they increase the density of bits squeezed into each square inch of surface space. More bits on a disk means more data that can be stored.
But as the bit density increases, the grains get closer together—so close that the magnetism of each grain can influence the magnetic direction of the grains next to it. The stability of each grain at normal temperatures (“thermal stability”) becomes a problem; the only way to fix this is to make the disk platter out of new materials that make the grains more thermally stable so that the grains don't influence each other.
This solution works—it makes each bit very stable, even at room temperature—but it creates a second problem: how do you get a very stable bit to change its magnetic direction when you need it to? How do you write new data to a hard drive if the grains are very thermally stable?
The company long ago decided that the solution was to momentarily heat a microscopic section of the disk large enough to write a single bit of data to it. It came up with this HAMR approach back in 2007 and has been working on it ever since.
To write new data, a small laser diode attached to each write head momentarily heats a tiny spot on the disk, allowing the write head to reverse the magnetic polarity of one bit at a time, allowing the data to be written. Each bit heats and cools in a nanosecond, so the HAMR laser has no effect on the temperature of the drive at all, or on the temperature, stability, or reliability of the media as a whole.
Last year, Seagate announced that it had successfully created a HAMR drive and has since made them available to a few select customers. The Mozaic 3+ are now entering mass production.
Tom's Hardware notes that Western Digital uses a similar technology known as energy-assisted perpendicular magnetic recording (ePMR) to offer its own 32TB drives. It also heats the platter, but it uses an electric current rather than a laser to do so.
The drives are currently aimed at enterprise customers for use in data centers, but as with all storage technologies, we can expect them to make their way into consumer products over time.
Image: Seagate
