Seagate multi-actuator hard drives think two heads are better than one


Technologies like shingled magnetic recording (SMR), heat-assisted magnetic recording (HAMR), and microwave-assisted magnetic recording (MAMR) all promise to improve the capacity of spinning platter drives, but none of them were developed with performance in mind. While HAMR and SMR could indirectly offer better throughput by way of increased data density, large jumps in hard drive performance have been rare in recent years. Seagate says its multi-actuator technology could double hard drive performance while maintaining magnetic hard drives' advantages over SSDs in cost per storage unit.

Discussion of Seagate's tech requires a bit of background on how hard drives typically work. Large-capacity drives have as many as 10 platters (Seagate's product stack currently tops out at eight spinning metal-coated discs). A read-write head is positioned on an arm on either side of each platter. All the arms in a drive are connected to a single actuator that positions the heads above different areas on the spinning platters. The tolerances inside a hard drive are so tight that only a pair of heads on either side of the same platter can reliably read or write at once. Seagate aims to manufacture drives with two actuators on the same pivot point, each capable of completing an independent read or write operation on any of half of the half the platters within a drive at one time.

Simultaneous operation of two heads could double the throughput of a drive or double the drive's maximum IOPS capability. Seagate says multi-actuator drives could present two parallel access streams to the same drive. The heads attached to either actuator can perform two reads, two writes, or one read and one write operation simultaneously.

Paul Alcorn of Tom's Hardware says that Seagate's multi-actuator drives have a second magnet that couples with the voice coil magnet assembly, implying that manufacturing costs will be somewhat higher than conventional drives. Management of two heads will require a more sophisticated controller and more complex firmware than current drives, but according to Alcorn, this probably represents less of a challenge. He also notes that weight and power consumption of devices with the new technology will probably increase somewhat.

The company says the multi-actuator technology could be extended to drives with more than two actuators in the future, given refinements to the manufacturing process. Seagate didn't provide any pricing or availability information, but the wording of the company's blog post suggests that multi-actuator drives will come to the data center first.

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