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WD Explains Its Windows-Only Software-Based SSHD Tech

Posted by timothy on from the horse-before-the-cart dept.

crookedvulture writes "Seagate and Toshiba both offer hybrid hard drives that manage their built-in flash caches entirely in firmware. WD has taken a different approach with its Black SSHD, which instead uses driver software to govern its NAND cache. The driver works with the operating system to determine what to store in the flash. Unfortunately, it's Windows-only. You can choose between two drivers, though. WD has developed one of its own, and Intel will offer a separate driver attached to its upcoming Haswell platform. While WD remains tight-lipped on the speed of the Black's mechanical portion, it's confirmed that the flash is provided by a customized SanDisk iSSD embedded on the drive. The iSSD and mechanical drive connect to each other and to the host system through a Serial ATA bridge chip, making the SSHD look more like a highly integrated dual-drive solution than a single, standalone device. With Intel supporting this approach, the next generation of hybrid drives appears destined to be software-based."

6 of 286 comments (clear)

  1. Unclear whether this is a problem or not... by fuzzyfuzzyfungus · · Score: 5, Interesting

    It isn't clear, exactly, from TFA what the drive will look like when you plug it in. Both components(the HDD and the SSD) apparently can function as SATA peripherals; but they are both behind some sort of bridge chip, type unspecified.

    If the 'bridge chip' is just a reasonably generic SATA port multiplier, then an unsupported OS, or Windows without the driver, will just see two drives, the larger mechanical one and the smaller flash one. This would leave the way open for any OS with SATA and AHCI support to do whatever it prefers to get the best performance(on Linux, I assume that'd be at the filesystem level, with something like btrfs)

    If the 'bridge chip' is some sort of proprietary oddity, and the vendor driver is required to even communicate with the flash portion(presumably at least some part of the drive will be visible as a normal SATA device, or booting without specific BIOS support would be a problem...), then that's pretty much worthless.

    1. Re:Unclear whether this is a problem or not... by EvanED · · Score: 5, Interesting

      Unclear whether this is a problem or not...

      IMO it's a problem either way. The Intel "Smart Response" stuff that they introduced as a chipset feature a year or two ago (you put a HDD and SSD in your computer and it will cache stuff on the SSD) works similar. A neat idea, but a non-starter for what I wanted. Why?

      Even if it works fine in Windows and works fine in Linux, it may still not really work if you want to dual boot. If you want to be able to use the SSD cache in both operating systems, they have to be able to not step on each others toes. If you want to be able to read data from the other OS, it has to be able to understand the format the other is in. (Potentially this could be "doesn't have to do anything in particular" if you make it a write-through cache, but write-back caches might have more stuff. And you still need to understand the format to write if you have a write-through cache.)

      Obviously not everyone needs dual booting, but not everyone needs Linux support either. It's a bit selfish to say that it's a problem if there is only support in Windows, but it's not a problem if there is support in both OSs but the support isn't compatible. :-)

  2. I like WD drives (had good luck with 'em) but... by Chas · · Score: 5, Interesting

    As an end-user, I'm NOT going to put up with a solution like this.

    Even if it somehow performs better than current hybrid drives.
    Even though most of my work is done on a Windows platform.

    Hybrid drives are already a big compromise for minute gains.
    Tying it to an OS choice?

    NO FUCKING THANKS WESTERN DIGITAL!

    In a budget situation I'd rather just put up with a competitor's hybrid or a plain old mechanical disk.
    In a performance situation I'd rather just spring the extra cash for a real SSD. Better returns and more flexible.

    --


    Chas - The one, the only.
    THANK GOD!!!
  3. RAM by Anonymous Coward · · Score: 2, Interesting

    And its worth reminding people, that Windows already caches stuff in RAM, if you had 24GB of ram then it would be a lot faster cached, and the only gain with these drives is on startup and then not by much (since Windows arranges the disk so the common items are close together ready for boot).

    So WD simply remind everyone why hard disk makers are struggling to remain relevant.

  4. Re:Stop. Hammer time. by girlintraining · · Score: 5, Interesting

    No. With SSD caching you get all the capacity of rotating disks with > 80% of the speed of SSDs.
    That is not the worst of boths worlds. It is the best of one and most of the other.

    No; You can achieve that with a separate SSD and a mechanical drive; That's what most people are doing now anyway.

    By putting the two together, what you're basically getting is a mechanical drive with a massively large cache. And because you now have two drives married behind a single logical interface, you've decreased the life expectancy further -- if either fails, it's a boat anchor.

    --
    #fuckbeta #iamslashdot #dicemustdie
  5. Re:Win modem by tlhIngan · · Score: 4, Interesting

    Should apply well to windisks too, I guess.

    Except these disks are more standard. They're basically an SSD and a HDD hooked to a SATA multiplexer (that lets you connect more than one SATA device to a SATA port. NOTE: Note all controllers support MUXes. Also, both drives share the bandwidth of the upstream port).

    So plug this into a Windows PC and install the drivers, and two drives become one. Plug it into a Linux PC and you see two drives. Plug it into a Windows PC without drivers and again, you get two drives.