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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  • DanNeely - Tuesday, March 5, 2013 - link

    These are much cheaper though. The Momentus never gained much traction because it was too expensive to serve as a mass market substitute for magnetic drives. Seagates current 500gb/1tb laptop drives are priced at $60/95 on newegg vs $130 for the old 500GB Momentus; a $20/5 price premium is a lot easier to swallow than a $70 one. At that price you might as well get a 32/64GB cache SDD and a standard HD instead.
  • tipoo - Tuesday, March 5, 2013 - link

    I got the second gen 750 for 130, I thought the 500 was cheaper than that by now.
  • DanNeely - Tuesday, March 5, 2013 - link

    Must've been a sale price. Newegg isn't listing that one at all, and Amazon wants $140 for it.
  • lmcd - Thursday, March 7, 2013 - link

    LOL my 500GB was $50 on sale.
  • mayankleoboy1 - Tuesday, March 5, 2013 - link

    Its like the marketing guys told Seagate that they needed a "NAND" in the checklist. So the engineers came with this solution.

    If these can do startup and shutdown similarly to a real SSD, i guess its OK.
  • rwei - Tuesday, March 5, 2013 - link

    I was pretty happy with the performance of my 7200rpm laptop drive. I did eventually jump on a 256GB (240? don't remember) Vertex 3 since they got so ridiculously cheap and I had a second drive bay.

    Honestly, other than the boot time (now like 16-20s on Windows 7) I didn't notice a big difference. I don't open enough things to care about 0.5s vs. 1.5-3s load times.

    You know where I do notice a difference? Loading stuff off of my secondary 1TB 5400RPM drive, which I use primarily for media storage. I'd like to see 8GB of cache help with that.

    This decision baffles me.
  • Mr Perfect - Tuesday, March 5, 2013 - link

    Looks like the race to the bottom has claimed another fine product. I wonder how this will impact sales? Anyone savvy enough to buy a SSHD in the first place is probably going to be checking technical specifications.
  • name99 - Tuesday, March 5, 2013 - link

    "This makes absolutely no sense."

    Oh grow up. These drives are VASTLY cheaper than their Momentus XT predecessors.
    You may not like their specs, and I don't either, but pretending they are "poorly designed" is just stupid. Seagate know their market better than you do, and I suspect these drives will sell in far higher volumes than Momentus XT ever did.

    If you're going to criticize something, criticize the things that appear foolish, even within the business context. Playing games about "some writes will be cached --- but we won't tell you which ones" is ridiculous --- it makes them look like they plan to sell vaporware ("buy our crappy firmware today but we promise it will be updated soon" "how soon?" "well, in about the same amount of time it takes to update the average Android phone...").

    And I don't see what strange market segmentation games they think they are playing by keeping a cache off their 3 and 4TB drives. Yes, you could argue that those drives are primarily purchased as large streaming storage for movies and music, and 8GB is small. But 8GB would hold the indexes for the drives --- for the Mac the various HFS+ data structures and Spotlight indices, for Windows the equivalents --- and would still make them feel more responsive in every day use.
    The message Seagate SHOULD be sending is "hybrid drives are the future and we are going all in to do them well"; the message they are actually sending is "we don't know WTF we are doing, but please buy these things if you're buying low-end".
  • piroroadkill - Wednesday, March 6, 2013 - link

    Seagate does know the market, and with the "solid state" part of the name they will stick these in laptops and get a bullet point that confuses the average joe.

    It's still a product that has specifications designed by marketing, not by the engineers.
  • Wolfpup - Wednesday, March 6, 2013 - link

    Yep, these look worse. I mean if you're looking for a 5400RPM drive, then okay, but the second gen Momentus XT uses SLC, probably has 4x the RAM cache, and of course the drive itself is slower.

    I have to say I'd rather have a normal 7200RPM drive than a hybrid 5400RPM drive. I suppose from their perspective they're hoping to reduce devices they have to design and build, but I don't want to go back to 5400RPM...

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