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posted by Fnord666 on Wednesday January 10 2018, @10:22AM   Printer-friendly
from the never-enough-storage dept.

The Register asked Seagate's Director of Technology Strategy and Product Planning Jason Feist about the company's plans to use multi-actuator technology in upcoming hard disk drives. Seagate insists that the technology can double input/output operations per second (rather than increasing it by, for example, 1.8x), and says that customers have validated the concept:

Howard Marks, founder and chief scientist at Deep Storage Net said: "We've had drives with 2 positioners before (IBM 3380 - one set of heads were dedicated to inner tracks, the other to outer tracks). That was back in the day of linear voice coils so they came from opposite sides of the 14-inch platters."

He identifies a software issue with Seagate's multi-actuator single pivot design: "Most storage software including logical volume managers and file systems, are built with the knowledge that a disk drive can only have it's heads in one place at a time and their queuing logic may mismatch with the multipositioner logic." This means: "It may not double throughput for large I/Os."

It could get close though, as "I understand that Seagate is going to make these look like 2 logical drives via a driver. That should solve #1 above and let systems get 1.8-1.9X IOPS."

[...] El Reg: What are your ideas and thoughts about multi-actuator disk drives and the arguments for and against them?

Jason Feist: We are bullish on this technology. A number of key customers have validated the concept and are working closely with us on the development of the technology.

Hyperscale data center service-level agreements (SLAs) are a critical factor in defining storage deployment needs and designing next-generation technologies that efficiently support storage deployments. In order for TCO (total cost of ownership) to continue to improve, the IOPS of a disk drive need to increase along with the capacity increases we're enabling with new areal density advancements.

The small cost adder that is required for additional components to deliver this performance gain is a much more cost-effective solution than using additional drives/spindles. The hard drive and SSD have a strong relationship in a data center, and both are required to achieve capacity and performance requirements at scale.

The IOPS growth provided by Multi Actuator technology in disk drives enables this relationship to continue to scale into the future.

Original Submission

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Seagate to Double HDD Speeds With Multi-Actuator Technology 17 comments

Future Seagate HDDs will begin including two separate sets of actuator arms that can operate independently in order to double read/write speeds:

Seagate's multi-actuator technology is a simple concept, and the idea certainly isn't new. In fact, the company has already developed drives with multiple actuators in the past, but they weren't economically viable due to higher component costs.

Most HDDs read and write data to and from multiple platters. For instance, Seagate's largest drives wield up to 8 platters and 16 heads. The heads, which are connected to the end of an actuator arm assembly, read and write data from both sides of each platter.

Unfortunately, those 16 heads are all aligned on the same arm, which means they all move in unison. Simultaneously aligning all the heads on all the platters isn't possible because of the incredibly thin data tracks on the platters, so only one of the heads is actively reading or writing data at any given time. That limits read/write throughput and performance with randomly accessed data.

Seagate's new design uses two sets of actuator arms that operate independently. Each carries eight heads. That means the drive can read or write from two heads at once, provided they are attached to different actuator arms. The drive can respond to two commands in parallel and one head can read while another writes, or both can read or write simultaneously.

Original Submission

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  • (Score: -1, Spam) by Anonymous Coward on Wednesday January 10 2018, @10:40AM

    by Anonymous Coward on Wednesday January 10 2018, @10:40AM (#620424)

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  • (Score: 2, Interesting) by Anonymous Coward on Wednesday January 10 2018, @01:10PM (1 child)

    by Anonymous Coward on Wednesday January 10 2018, @01:10PM (#620448)

    The current drivers schedule transfers to minimize head movement while servicing a list of requests.
    That is different than scheduling the head pair movements.
    This is interesting because you are dealing with both seek and rotational latency.

    Eventually, then need a new ordering algorithm.
    Until that they could
    a) move both heads in step, then tell the driver the drive spins twice as fast.
    b) treat the drive as 2 separate drives, each with half the number of cylinders and one head.
    c) maybe treat the drive as 2 whole drives, one of which is read only?

    Other options?

    • (Score: 2) by HiThere on Wednesday January 10 2018, @06:12PM

      by HiThere (866) Subscriber Badge on Wednesday January 10 2018, @06:12PM (#620548) Journal

      I like option C if it's easy to switch which "drive" is read-only. Preferable by a toggle switch on the outside of the case.

      Put not your faith in princes.
  • (Score: 3, Insightful) by linkdude64 on Wednesday January 10 2018, @07:20PM (2 children)

    by linkdude64 (5482) Subscriber Badge on Wednesday January 10 2018, @07:20PM (#620579)

    Twice the points of failure, at minimum. If this idea isn't 1st semester product design, it really should have been.
    HDDs should not try to become SSDs! They have their place as time-tested and reliable holders of relatively large amounts of data. With more information at stake, reliability should be the first concern - otherwise you just end up, as the article states wanting to avoid - buying more drives! Only this time it's not to increase their speed, but their reliability!

    I suppose only time will tell about the longevity of these drives, but given Seagate's already abyssal failure rates, I am not holding my breath for these to be winners.

    • (Score: 0) by Anonymous Coward on Wednesday January 10 2018, @08:31PM

      by Anonymous Coward on Wednesday January 10 2018, @08:31PM (#620609)

      *Proudly wears the silly badge*

    • (Score: 0) by Anonymous Coward on Thursday January 11 2018, @03:18AM

      by Anonymous Coward on Thursday January 11 2018, @03:18AM (#620785)
      Except that the spinning bit is still the same point, instead of two. So that's not one additional point of failure.

      Thing is with this you might be able to use two drives as a RAID10, rather than needing four drives. But that's only if they really can make a single drive look like two independent drives without sacrificing too much throughput.

      Do it right and if one physical drive fails the other drive still has the full data.
  • (Score: 1, Interesting) by Anonymous Coward on Thursday January 11 2018, @12:19AM (3 children)

    by Anonymous Coward on Thursday January 11 2018, @12:19AM (#620731)

    For a given place on the disk, they are NOT providing 2 heads, each with a seek mechanism.

    Instead, they have one spindle with a bunch of platters.

    The heads for the lower half of the platters are on one actuator.
    The heads for the upper half of the platters are on another.

    This is just like putting 2 drives of half capacity in one box with a common spindle.
    Just treat them as two separate drives and there is not much else to do.
    This thing should be no faster than 2 separate drives each with half the capacity.

    So, if speed is important why not put 2 heads per track?
    Probably because it is cheaper to just have more drives.
    This is basically 2 drives in one with a slight speed reduction because of a common control interface, but an advantage because it is smaller.

    This may be a sign of the times. Drives are getting so big that it takes too long to use them.

    • (Score: 2) by takyon on Thursday January 11 2018, @07:57AM (2 children)

      by takyon (881) Subscriber Badge <reversethis-{gro ... s} {ta} {noykat}> on Thursday January 11 2018, @07:57AM (#620841) Journal

      This may be a sign of the times. Drives are getting so big that it takes too long to use them.

      This has been a problem with HDDs for years. Multi-actuator could alleviate it slightly.

      SSDs already come in larger capacities than HDDs and will hit 100 TB before HDDs even hit 20 TB. SSDs can have much higher sequential read/write speeds. But HDDs will probably stick around as long as they have a lower cost per bit.

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      • (Score: 0) by Anonymous Coward on Thursday January 11 2018, @11:17PM (1 child)

        by Anonymous Coward on Thursday January 11 2018, @11:17PM (#621170)

        I sure have not seen many 10TB SSDs out there. Where can I buy them? I have seen a couple of prototype 16TB SSDs but nothing to buy yet. Bellow 100gig you are correct. But at the higher sizes HD still is the champ. Considering the way prices have stalled out and capacities have not changed in a year it would not surprise me that the SSD manufactures all got together and colluded (yet again).

        • (Score: 2) by takyon on Thursday January 11 2018, @11:47PM

          by takyon (881) Subscriber Badge <reversethis-{gro ... s} {ta} {noykat}> on Thursday January 11 2018, @11:47PM (#621181) Journal

          The big drives are aimed towards data centers and other enterprise customers. It doesn't make sense to make a consumer-oriented SSD (cheaper, less warranty) because most consumers don't want a multi-thousand dollar SSD.

          A 4 TB consumer SSD costs $1,500. That's in a 2.5" form factor.


          There we have it. Someone who will sell you a 15.36 TB SSD (larger than any hard drive a consumer can get), for a reasonable $11,625.

          I never claimed that SSDs were more affordable than HDDs. Just that they are getting dense fast. There is absolutely no technical barrier to creating a 128 TB 3.5" prototype SSD today. It can be done, but it will be an expensive niche product on release. There is no way to create the equivalent HDD until many years of research are completed. Fast forward a few years, and SSD manufacturers can create 4-bits-per-cell (QLC) NAND dies with well over 96 layers, and then stack those dies into thick packages (1 TB today, probably 8+ TB later). Then they can stuff as many packages as possible into a 2.5" or 3.5" enclosure. They have a clear path to creating 1 petabyte or larger SSDs. WD and Seagate have a murky path to creating 100 TB HDDs, using technologies such as HAMR, MAMR, and bit-patterned media.

          WD and Seagate could produce a 100 TB hard drive by around 2030. Any SSD manufacturer (a group of companies that includes WD and Seagate) can make and sell a 100 TB SSD before 2020.

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