We were lucky enough to test what is currently the largest available version, which has 500 GB, but the Momentous XT also comes in 250 GB and 320 GB versions. They all use a 3 Gbps SATA-2 interface, have 32 MB of cache and come in the 2.5'' format allowing them to fit into a laptop or desktop PC. The hard drives spin at 7200 rpm, but the most interesting element is the 4 GB of flash memory that makes these drives hybrid devices. The SLC type memory should have a better lifespan than the MLC found in other SSDs.
Management of the hybrid drive is totally invisible to the user, who only sees a single hard drive. The Momentus XT handles the flash memory itself, gradually storing small, frequently-used files there so they can be accessed more quickly. Seagate's Adaptive Memory Technology relies on an algorithm which optimizes the storage of different types of file. That means performance changes over time as you continue to use the Momentus XT. We'll start our review by reporting our initial measurements, before looking at how its performance evolves over time.
Pure performanceBefore we start, we should remind you that unlike our final score, this part of the review is based on a comparison with all of the hard drives we have tested, including the most powerful SSD models.
The initial figures aren't stunning, even compared to conventional hard drives. The Monmentus XT is just a little better than entry-level models like the WD Caviar Green or the Samsung EcoGreen F3. If we take into account the fact that this is a 2.5'' drive, it does well compared to other storage solutions in this form factor. It easily beats the Scorpio Black, for instance, which tops out at 85 MB/s and 81 MB/s respectively for reading and writing data, with figures around 55 MB/s for 512 KB/s.
That's equivalent to a good 2.5'' drive, as the results from the AS-SSD confirm:
Our next thought was that the SSD memory in the Momentous XT should allow it to enjoy excellent access times. And they most certainly aren't comparable to what we've found on other 2.5'' drives:
It's important to remember that our test procedures don't take into account the algorithm that optimises the use of SSD memory to make sure it only works on new files. That's something we'll take a look at at the end of our review.
Performance in practiceOur analysis of the PCMark Vantage test results confirmed that this is a very good 2.5'' hard drive whose performance is equivalent to that of a drive in the 3.5'' hard drive format.
With real-life practical tests, the results are a little less impressive:
Repeating the PCMark tests shows that the performance gradually improves over time.
The results from seven different tests
Each time we ran the test, the performance was better than the last. The Adaptive Memory Technology algorithm allowed the Momentus XT to double its final PCMark Vantage score by the end.
Unfortunately, once you start using other software, the performance boost falls off again because there's only 4 GB of SSD memory, which isn't enough room to store a lot of files, so the items stored there are quickly replaced. It's a clever idea, but its real-life usefulness is limited. If you use more than two or three big piece of software on a regular basis, you won't be able to take full advantage of Adaptive Memory Technology.
All in all, the Momentus XT doesn't actually offer the best of both worlds, only offering improved performance in certain areas. It offers the storage space of traditional hard drives, but is as susceptible to accidental damage during a fall as well as producing noise while the platters spin—and all without achieving the exceptional performance boost of a pure SSD drive.