A few days ago we reported that Seagate would stop selling 7200 RPM 2.5” hard drives by the end of the year. Now we know why. Seagate will continue to offer 5400 RPM 2.5” drives, but if you want more performance without diving into the performance/capacity tradeoffs of an SSD Seagate will offer you its 3rd generation solid state hybrid drive (SSHD).

Once sold under the Momentus XT brand, the 3rd gen hybrid drives will simply be sold under the SSHD moniker. As Seagate alluded to many times in the past, we’ll also be getting a 3.5” hybrid drive as well. The two families will simply be called the Seagate Laptop SSHD and Seagate Desktop SSHD.

While both families will have many members, at launch we’ll see the following:

Seagate SSHD Lineup 1H 2013
  Capacity Form Factor Platters Speed NAND Price
Seagate Laptop SSHD 500GB 2.5" 7mm 1 5400 RPM 8GB MLC $79
Seagate Laptop SSHD 1TB 2.5" 9.5mm 2 5400 RPM 8GB MLC $99
Seagate Desktop SSHD 1TB 3.5" 1 7200 RPM 8GB MLC $99
Seagate Desktop SSHD 2TB 3.5" 2 7200 RPM 8GB MLC $149

All of the drives use a standard SATA interface, and all of them feature 8GB of MLC NAND (with a small portion of the NAND set aside for use in SLC mode, similar to SanDisk’s nCache). This is a disappointingly small amount of NAND, however Seagate hinted at future, higher performance versions shipping with somewhere around 32GB of NAND. As we found in our investigation of Apple’s Fusion Drive, the ideal number is likely somewhere in the 128GB - 256GB range but that puts you in a very different price class.

The benefit of using only 8GB of NAND is that Seagate is able to keep prices very low. Both Laptop and Desktop SSHDs are expected to carry around a $15 - $20 price premium over competing 7200RPM alternatives.

The NAND mostly acts as a read cache, although this time around Seagate claims it will be able to cache some writes. Seagate is understandably sensitive to writing tons of data to the NAND since it’s only an 8GB MLC device, but endurance shouldn’t be too much of a problem to navigate around with good firmware. There’s no data separation, everything that is written to NAND also exists on the hard drive - although it’s not clear if that write happens in tandem or sequentially.

Seagate is particularly proud of their very low time to use performance with the new SSHDs. Apparently Seagate aggressively tuned its algorithms to cache roughly all accesses that happen within the first minute of power on.

Although I’m not very excited about the performance of these drives compared to SSDs, their low price should make Seagate’s SSHDs an obvious choice compared to a traditional hard drive. The fact that we’ll get both 2.5” and 3.5” SSHDs is nice since many SSD users on the desktop are still consumers of mechanical drives as well. Personally I’m not sure how much I’d benefit from using Seagate’s Desktop SSHDs in my RAID array since I mostly do large block sequential transfers (which would be uncached) to/from the array. For gamers or folks who have an SSD that’s smaller than their total application footprint these SSHDs might be compelling.

When I first reviewed the Momentus XT I concluded “There's no reason for any performance oriented mechanical drive to ship without at least some small amount of NAND on board.” Three years later, it looks like that vision has finally come to be.

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  • kyuu - Tuesday, March 5, 2013 - link

    Watch out, your ignorance is showing. The NAND, MLC or no, is likely to outlast the mechanical portion of the drive. Even if the NAND does fail, the drive is able to continue working without it (without the benefit of NAND caching, obviously).
  • paul878 - Tuesday, March 5, 2013 - link

    What is the life expectancy for the 8g of MLC?
  • HisDivineOrder - Tuesday, March 5, 2013 - link

    ...I'd really rather see WD get up off their hands and give us the Raptor we all wish they'd make.

    A 10K RPM Raptor with 64 gigs of MLC and a large bit of memory for cache. Pop it out at 1 TB for $200-$300, people would gobble that up.

    As it is, I think Seagate should have pushed the MLC component up to 16 gigs as a baseline with the 32 for the high end 3/4 TB versions.

    8 is going to be really, really pathetic.
  • ShieTar - Wednesday, March 6, 2013 - link

    Except for the fact that 1TB SSDs will probably hit $300 early next year, at which point that raptor would become absolutely useless.

    As it is, you can already go and pair the current 1TB raptor with a 64GB cache-SSD by yourself for around $300, but that same money also buys you a good 500GB SSD. Who needs more than 500GB desperately but is happy with 1TB? And do you really expect WD to develop a special drive for this tiny group of customers?
  • Creator1326 - Tuesday, March 5, 2013 - link

    I have the first Momentus SSHD and it's hard to believe that the big new announcement is STILL 8GB? Underwhelming. It should be closer to 64-128GB like Apple's "Fusion Drive".
  • kyuu - Tuesday, March 5, 2013 - link

    No, the big new announcements are 3.5" drives, and much lower price points on the new drives.
  • AnTech - Tuesday, March 5, 2013 - link

    Seagate hybrid drives are a JOKE with only 4 or 8 GB flash. See the Apple Fusion Drive for a good implementation (hint: 128 GB flash inside).
  • kyuu - Tuesday, March 5, 2013 - link

    Even the 1st-gen XTs with only 4GB were a huge improvement over standard HDDs is everyday usage. You can do a lot with even just 4GB-8GB with good firmware and caching algorithms. You can easily fit the file index and boot sectors in that, along with some commonly accessed blocks of system files and application data.

    Devices with more NAND would be great, and are certainly incoming. However, calling these a "joke" due to the small amount of NAND is just ignorant. Frankly, with these price points, I can't see any reason to get any other HDD unless performance just isn't a consideration.
  • Mr Perfect - Tuesday, March 5, 2013 - link

    The Apple Fusion "drives" are two physical devices, aren't they? I know people where talking about building their own Fusion setups by popping a SSD into a HDD only Mac. OSX saw that there was a SSD and HDD, marked it as a malfunctioning Fusion setup, and then offered to "rebuild" the array/cache/whatever.
  • Wall Street - Tuesday, March 5, 2013 - link

    Well, Apple charges $250 to upgrade a 1 TB HDD to a 1 TB Fusion - I don't think that Seagate has that as a target market. Also, I think people are misjudging their use of HDD space. For 99% of users, 128 GB or data is way way way more than enough to cache the IO intensive random read program data and is well into caching media files which don't really benefit from the flash storage. People in this thread have both complained about the cost of the drive relative to the 7200 RPM standard drives and the size of the cache, so I think the compromise is about right.

    Don't underestimate small amounts of Flash. Look how big 8 GB of RAM feels. Don't look at the size of your HDD and the size of your folder, 80% of your windows folder is fonts, unused drivers and the hybernate file - they don't need to be cached. I'm using a 32 GB flash cache and it feels plenty fast for windows boot and 90% of programs.

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