If you had asked me a few years ago, I would've said that hybrid drives will be the next big thing in the storage industry. Seagate's Momentus XT got my hopes up that there is manufacturer interest in the concept of hybrid drives and I was expecting the Momentus XT to be just the beginning with more announcements following shortly after. A hybrid drive made so much sense -- it combined the performance of an SSD with the capacity of a hard drive in an affordable and easy to use package.

Seagate's Momentus XT showed that even 4GB/8GB of NAND can make a tremendous impact on the user experience, although it couldn't compete with a standalone SSD. The reason for that was the very limited amount of NAND since the speed of an SSD relies on parallelism: a single NAND die isn't fast (though for random IO even it's still far better than a hard drive), but when you combine a dozen or more dies and read/write to them simultaneously, the performance adds up. I knew the Momentus XT was a first generation product and I accepted its limitations, but I truly expected that there would be a high-end drive with enough NAND to substitute for an SSD.

It turns out I was wrong... dead wrong. Sure Seagate doubled the NAND capacity to 8GB in the second generation Momentus XT, but other than that the hybrid drive market was pretty much non-existent. Western Digital showed their hybrid drives over a year ago but limited them to OEMs due to a unique connector. To be honest, I've not seen WD's hybrid drives used in any systems, so I'm guessing OEMs weren't the biggest fans of the connector either.

As the hard drive companies weren't able to come up with decent hybrid offerings, the PC OEMs had to look elsewhere. Intel's Ultrabook concept was a big push for SSDs because Intel required at least 20GB of flash storage or the OEM wouldn't be able to use Intel's Ultrabook branding. Of course Intel had no weapons to stop OEMs from making ultraportables without flash but given the millions Intel has spent on Ultrabook marketing, it was worthwhile for OEM's to follow Intel's guidelines. Since the PC market kind of pushed itself into a corner with the price war, it wasn't possible for PC OEMs to do what Apple did and go SSD only due to prices, but on the other hand Ultrabooks had no space for two 2.5" drives. The solution? mSATA.

mSATA is barely the size of a credit card

Unlike hard drives, SSDs didn't have to be 2.5", it was simply a matter of compatibility with existing systems. What mSATA did was allow PC OEMs to build hybrid storage systems while keeping the Ultrabook spec and form factor. In my opinion this was a huge yet missed opportunity for hard drive OEMs. All they would have needed to do was build a hybrid drive with at least 20GB of NAND in order to meet the Ultrabook spec. I bet many PC OEMs would have chosen an all-in-one hybrid drive instead of two separate drives because managing a single supplier is easier and assuming sufficient volume the pricing should have been competitive as well.

When SSDs first appeared in the consumer space, the hard drive companies didn't feel threatened. The pricing was absurd (the first generation 80GB Intel X-25M cost $595) and performance wasn't much better than what hard drives offered. Back then SSDs were only interesting to some enthusiasts and enterprises, although many were unconvinced about the long-term benefits since the technology was very new. The hard drive companies had no reason to even think about hybrid drives as traditional hard drives were selling like hot cakes.

Today the situation is very different. Let's take the 80GB Intel X-25M G1 and 240GB Intel SSD 530 as examples: the price per gigabyte has dropped from around $7.50 to $0.83. In percentage points, that's a massive 89% decrease. Drops this big are impossible to predict as they usually aren't intentional and neither was this one. The reason why NAND prices dropped so rapidly was the oversupply caused by large investments made around 2010. The sudden increase in NAND demand due to the popularity of smartphones and tablets made the NAND business look like a good investment, which is why many companies invested heavily on it. While smartphone and tablet shipments continued to increase, the thing NAND fabricators didn't take into account was that their capacities didn't (at least not very quickly). In other words, the NAND fabricators expected that the demand for NAND would continue to grow rapidly and increased their production capacities based on that but in reality the demand growth was much smaller, which lead to oversupply. Just like other goods, NAND prices are controlled by demand and supply: when there's more supply than demand, the prices have to come down for supply and demand to meet.

SSDs are no longer luxury items. Plenty of systems are already shipping with some sort of SSD storage and the number will continue to grow. The hard drive companies can no longer neglect SSDs and in fact WD, Seagate, and Toshiba have all made substantial investments regarding SSDs. Last year WD acquired STEC, Virident, and Velobit; Seagate introduced their first consumer SSD lineup, and Toshiba has been in the SSD game for years. However, there still hasn't been a product that would combine an SSD and hard drive into one compact package. The WD Black2, the world's first SSD+HD dual-drive, changes that.

The Drive & The Test
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  • Crocodile2014 - Wednesday, February 5, 2014 - link

    The Seagate Hybrid Drive could have been epic... it could have taken the market by storm... but it didn't. WHY? Because they overpriced the thing out of the market.

    A 500Gb Seagate Hybrid drive should have been priced very similar to a 500Gb Hard Drive + 8Gb of NAND. Instead we got a device priced at the level of a 500Gb Drive with a 30Gb SSD. Why did they do this?

    I get you pay a "performance premium" but when the alternatives for better performance are cheaper, you've really missed the mark.

    I suspect this drive by WD will also be a fail except for OEM's wanting a smaller package for their ultrabooks also based on the price.
  • SDKat - Friday, February 7, 2014 - link

    Amazon has a best price of almost $300 for a 1TB HD with 120 gb SSD.
    FAR cheaper (by about half) to buy a 1 TB HD and separate SSD. AND more versatile too!
  • coder111 - Friday, February 7, 2014 - link

    On scale of 1 to 10, how useless is this drive on Linux? If it needs special drivers to work properly, are these drivers available in Linux? Since which kernel version? Are they open-source or a buggy binary blob?

    If it works with Linux, does it show up as 2 separate drives, or as 1 combined accelerated drive? If it's 1 combined accelerated drive, how does the performance compare to having dedicated SSD + dedicated hard drive combined using Linux BCache or dm-cache?
  • ivan256 - Wednesday, February 12, 2014 - link

    The Momentus XT is the least reliable hard drive I have ever experienced. The various iterations of it haven't improved on the situation much. I have seen failure rates of more than 50% in 18 months out of a sample size of hundreds of drives.

    The NAND wears out way sooner than it should. Failure isn't catastrophic, because there is a copy on the rotating media, but the NAND access failures slow the drive down to a more pathetic level than you would expect even from the slow legacy portion of the disk.

    They need to get the reliability up to be taken seriously. And then they need to pair the tiny amount of flash with a much faster disk.
  • Haravikk - Monday, March 3, 2014 - link

    I just don't get the point of these drives at all; okay, so putting the two drives into one bundle is neat, but the fact that you need software to actually run it is just bewildering. Why not include hardware on the disk to manage the split between SSD and HDD, and just let users configure that as either a SATA multiplier (two disk) or a hybrid disk as desired? Shipping it as a hybrid as standard would not only make it compatible with Linux and Mac computers too, but also make things so much easier.

    Instead you're getting two, not every good, individual disks in a single package. I mean, 350mb/sec sequential read is decent, but hardly amazing, plus that's competing with traffic going to the HDD at the same time.

    It just seems a very messy way to produce a product that I'm not sure many people really need. I'd personally rather go with a (much cheaper) hybrid drive, assuming one 2.5" drive is all I can fit. While 8gb flash gives far from the hybrid SSD performance advertised, it's just so much simpler to setup and manage (no juggling of separate volumes) and works pretty well in real-world use.

    A shame, I got really excited thinking WD were making a hybrid with 128gb of flash, i.e - something that would actually be really useful.
  • danwat1234 - Sunday, January 25, 2015 - link

    I don't think the SATA protocol allows for more than 1 drive per channel. So, the drive couldn't have been designed to act as 2 separate drives to the controller.
  • BDProductions - Thursday, May 1, 2014 - link

    I have to wonder at the author's comment about his photos..
    WTF do you need a DSLR for to take great images?

    Ever hear of a scanner?

    - Set item on glass, cover with black velour, scan, instantly AWESOME images. (you may choose another solid color to cover the item, or even turn out the lights instead when you scan)

    Some scanners do better than others for material not touching the glass, but most look better than the pictures in this article...

    I have a question nobody seems to address... WHY IS THERE A MANDATORY DOWNLOAD instead of just putting the drivers on the USB thumbdrive? That makes no sense, other than to FORCE you to register the drive with WD.

    That will keep me from buying such a product.

    How stupid is it to make such an artificial requirement when a person might want to install the drive in a remote location where not even a cellular data connection would work? Just because anyone reading this has no such worry does not validate their theory that everyone these days MUST have an internet connection where ever they are... that just isn't true.

    Some users may have remote locations with little more than power, and still NEED a replacement drive with the Black2's functionality for performance reasons.

    Anyway, who has installed one and been able to save the "drivers" downloaded from WD at install time?

    If you can save them, how big is the package, and why would it not make sense to have included the driver on the thumbdrive instead of a forced download?

  • bungle2000 - Tuesday, December 9, 2014 - link

    Has there ever been a review of the Toshiba (500Gb/8Gb) Hybrid HDD SSD Drives on AnandTech?
  • danwat1234 - Sunday, January 25, 2015 - link

    It's down to $130 on Amazon/Newegg/Ebay! Now it's a great buy. Wish it had a 7200RPM drive though
  • Aseries - Friday, February 20, 2015 - link

    I have two HP gaming laptops that have a mSATA slot with a 32 GB micro SSD installed running Raid 0 with the a 7200 RPM drive using Intel Rapidstore driver. Two years ago it was a reasonable solution. Laptop #1 has two 7200 RPM 1 TB drives in the two drive bays available. Today I would use a 240 GB SSD drive paired with the largest available 2.5 inch 5400 RPM drive. Laptop #2 has only one drive bay. Without the mSATA option I would definitely consider the WD solution.

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