History Repeating: Multi-Actuator Technology

About two years ago we published several articles regarding consolidation of hard drive manufacturers and today’s story is closely related to this subject. Once upon a time, there was a company called Conner Peripherals. Before Seagate acquired Conner, and became the new owner of Conner’s intellectual rights they patented a hard drive design that utilized multi-actuator design or a hard drive with two sets of read/write elements. Below is Conner Peripherals Chinook 510 MB drive.

multi-actuator

However, multi-actuators have never seen commercial application drives for several reasons: cost, extra components and weight gain as dual-actuator drives used to be larger, consumed more power and produced more heat. Although a multi-actuator drive was technically possible, it was expensive! This was not a surprise, in those days chips were primitive, expensive to make and there was no real market nor need for this kind of product.

So what has changed? Everything!

These days we use cloud storage, AI and IoT. We’ve developed first quantum computers. Detected gravitational waves and cracked human DNA! All of which requires storage. Lots of it! And we are going to need more, much more!

While WD and Seagate and to some extent Toshiba continue to roll out their new recording technologies future HDDs will increase capacity beyond 20TB and performance will likely become one of the biggest challenges. There is a limit to how much data each head can manage and increased capacities results in a lower input/output operations per TB. For example, most 3.5″ enterprise HDDs reach 200-250MB/s of sequential throughput. So a 20 TB HDD would take just shy of a day to fill!

To address this problem a few weeks ago Seagate announced plans to double performance using old-new multi-actuator technology. New design relies on two sets of actuator arms to operate independently. Each carries separate HSA and operates much like RAID 0? The drive can respond to two commands in parallel and one head can read while another writes or both can read or write simultaneously. This means only one thing, more complex firmware! Modern hard drives store detailed servo details about the physical makeup of the platters so fluctuations in heat (materials expand and contract differently at different locations on the disk) would have to be addressed separately and will likely be an extra burden to drive controller.

In its first generation, Seagate’s Multi Actuator technology will equip hard drives with two actuators operating on a single pivot point, each actuator will control half of the drive’s arms. Half the drive’s recording heads will operate together as a unit, while the other half will operate independently as a separate unit. This enables a hard drive to double its performance while maintaining the same capacity as that of a single actuator drive.

On a paper it sounds great but what about real life situations and the same problems from before? Cost, heat and complexity!
It seems that once again necessity is the mother of invention. For more than a decade the industry has largely used PMR (Perpendicular Magnetic Recording) now we will have two (plus?) recording technologies marking a new point in hard drive history. Seagate is moving forward with HAMR (Heat Assisted Magnetic Recording) while Western Digital plans to use MAMR (Microwave Assisted Magnetic Recording), both can enable up to 40TB HDDs by 2025.

This is just great news for all of us working every day on drives which need data recovered… another HSA to worry about!

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