It's been over a year since I reviewed Seagate's first hybrid hard drive: the 500GB Momentus XT. At the time I felt that it wasn't nearly as good as an SSD, but likely the best 2.5" hard drive money could buy. Armed with only 4GB of SLC NAND acting as a read cache, the original Momentus XT delivered VelociRaptor performance in a much more power efficient package. 

Since then Seagate hasn't updated or expanded its line of hybrid HDDs at all. I kept hearing rumors of new drives coming but nothing ever surfaced. More recently Seagate announced that the next version of the Barracuda XT will be a hybrid drive as well.

Today Seagate is announcing availability of its second generation Momentus XT. Now at 750GB with 8GB of SLC NAND (once again, as a read cache), the new Momentus XT is a definite evolution over its predecessor. With a larger NAND cache Seagate can be more aggressive with its caching, not to mention the improvements to the mechanical side of the drive as well. The entire package is still not nearly as fast a value SSD, but it's doing much better than mechanical (3.5" included) hard drives in our tests.

Write caching is still not enabled on the NAND, however Seagate is planning on enabling it via a firmware update sometime in 2012. I've seen results from an early version of the write caching firmware and the improvement is tangible. 

The 750GB Momentus XT will be available at a MSRP of $245.

We're still hard at work on our review of the drive, expect to see it later this week!

Update: Our review is live!

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  • Hubb1e - Tuesday, November 29, 2011 - link

    I'm glad they are sticking with this tech. The old XT solved my nearly 10 minute Vista bootup issues where Vista would take forever to stop hitting the harddrive. It caused my computer to be completely unresponsive after bootup and bootup happens often enough that it was a major issue for me. Rather than reinstalling all my software to windows 7 this simple $85 drive boots Vista64 in 3 minutes now. I don't care that much about absolute performance on this machine, but 3 min vs 10 min is a great upgrade for me.

    I studied my use case and the XT was perfect for me. I'm glad they are improving it but $250 is ridiculous. I'll wait till they are less than $100 to drop in my other machines.
  • alcalde - Tuesday, November 29, 2011 - link

    I don't understand the appeal of a write cache (other than for benchmark junkies). Are laptop users routinely hampered by needing to wait for disk *writes* as opposed to disk reads? Drives already have a standard buffer for this and the OS can use system memory to cache writes as well. In fact, for power-saving reasons, it's beneficial to delay writes on a laptop as long as possible (with a tradeoff in data safety).

    It would seem to me that real-world (as opposed to benchmark) performance would decrease if the NAND read cache capacity was diminished to set some aside for write buffering. Under normal use the user isn't going to notice write buffering (as it's likely rendered superfluous by a modern OS already caching writes and employing extra-long delayed writes on laptops) but will miss the extra read cache.

    The only scenarios I can see it being noticeable would be page/swap file use if the laptop was using all of its available memory and suspending to disk being faster (although this is again not something the user probably cares about anywhere near as much as resuming from disk).
  • DigitalFreak - Tuesday, November 29, 2011 - link

    26 - 34% faster than the old 500GB model, depending on the workload.
  • kyuu - Tuesday, November 29, 2011 - link

    Very nice. Now I just have to wait for HDD prices to drop back down to reasonable levels so I can consider these...
  • ezinner - Wednesday, November 30, 2011 - link

    I just bought the first generation 500 GB model for my laptop. The stock drive was starting to make a lot of noise and my boot time was too long. I was wondering if Seagate would be coming out with a larger drive with more NAND since this drive has been out for a while now, but I couldn't wait.

    I must say that I do see an improvement in my boot time and I love the added capacity.
  • etamin - Wednesday, November 30, 2011 - link

    I think a comparison of hybrid drives with Z68 SSD caching would be really interesting to see in the review as they appear to be physically similar solutions.
  • 2in1hdd - Monday, December 5, 2011 - link

    USA Patent

    Field of the invention
    The present invention relates to hard disks, and particularly to a composite single structured hard disk drive capable of receiving more than one recording disks. Moreover, in the composite single structured hard disk drive of the present invention, the RAID0 structure can be used. Furthermore, more disks and R/ W heads can be arranged in the machine casing of the present invention so that the speed is increased and the backup copy can be prepared. Furthermore, as comparing with other RAID array, the number of hard disks is decreased.
  • tipoo - Saturday, December 15, 2012 - link

    2012 is all but over, Seagate support gave me some useless response about where to find the latest firmware when I asked them, and I couldn't join the Seagate forums due to some bugs in their software. So where is the write caching firmware update?

    The latest firmware is still the one the 750 originally shipped with.
  • danwat1234 - Sunday, October 11, 2015 - link

    Seagate still hasn't released any write-caching firmware for this awesome drive! Does Anand have the early version of the write-caching firmware as a file and post it?

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