Astonishing 32TB hard drive uses lasers to heat and cool platters

Seagate finally launches its largest hard drive ever – a single drive with a staggering 32TB capacity, powered by science and technology It uses lasers to heat and cool tiny parts of the disc in a nanosecond…

Seagate has been working on heat-assisted magnetic recording (HAMR) technology for 17 years, and last year said it finally cracked the technology. The Mozaic 3+ 32TB hard drive is now in mass production and will be on sale soon.

The company explained the problem of trying to squeeze more data onto disk platters.

To increase hard drive capacity, engineers try to fit more data bits, or “grains,” onto each disk platter—they increase the density of bits crammed into each square inch of surface space. The more bits on a disk, the more data can be stored.

But as the bit density increases, the grains move closer together, so close that the magnetism of each grain affects the magnetic direction of nearby grains. The stability of each particle at room temperature (“thermal stability”) becomes an issue; the only way to solve this problem is to use new materials to make disk platters that make the particles more thermally stable so that the particles do not interact with each other.

This solution works – it makes each bit very stable even at room temperature – but it introduces a second problem: how to force a very stable bit to change its magnetic field when you want it to direction? If the thermal stability of the particles is very good, how can new data be written to the hard drive?

The company decided long ago that the solution was to temporarily heat a microscopic part of the disk that was large enough to write a single bit of data to. The company proposed 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 recording head momentarily heats a tiny spot on the disk. This allows the recording head to flip the magnetic polarity one bit at a time, allowing the data to be written. Each bit heats and cools within nanoseconds, so the HAMR laser has no impact on the drive temperature or the overall media temperature, stability or reliability.

Seagate said last year that it had successfully manufactured HAMR drives and had made them available to a few select customers. Mozaic 3+ is now in mass production.

Tom’s Hardcore points out that Western Digital is using similar energy-assisted perpendicular magnetic recording (ePMR) technology to offer its own 32TB hard drives. This also heats the platter, but uses an electric current rather than a laser.

Currently, these drives are aimed at enterprise customers for use in data centers, but as with all storage technologies, we can expect them to trickle into consumer products over time.

Picture: Seagate