Seagate has working HAMR drives, and has just demonstrated them. They have two controllers for faster disk access.
Seagate displayed the world's fastest hard drive today at the Open Compute summit and announced that it has surpassed industry reliability standards with its new HAMR HDDs.
The new drives use Seagate's Multi-Actuator technology, which we've covered in depth, to deliver twice the performance of a standard hard drive. Seagate has branded the new actuator technology as "Mach.2" and set a new record for a single hard drive with 480 MB/s of sequential throughput, which is more than twice the standard 235 MB/s of the speediest 7,200-RPM enterprise HDDs. It's also 60% faster than the leading 15K HDDs. The new drives are currently geared for the data center, but we expect the technology will eventually filter down to the consumer market.
The new drives have two sets of actuator arms that each contain their own array of heads. The host system can access each set of heads independently, thus providing twice the throughput.
With twice the performance in hand, Seagate also announced that its Exos drives will also soon have HAMR (Heat Assisted Magnetic Recording) technology that can enable up to 20TB of capacity in a single drive by using tiny lasers on data recording heads. The lasers heat the surface of the drive platter to over 400°C for a split second, which allows it to store up to 2Tb of data per square inch. We have much more in-depth coverage of the technology in our recent "Seagate Plans To HAMR WD's MAMR" article, including pictures of the new laser-infused recording heads, so head there for more detail.