Last year, during research for some project or another, we asked Seagate an offhand question about hybrid drives. Where nearly everybody said that hybrid drives (last seen circa 2005) were dead, Seagate said that the technology had shown promise, but that they had no further comment. We immediately assumed that meant they were working on one, and to our immense satisfaction, today Seagate announced the Momentus XT, a 2.5-inch hybrid drive featuring 500GB of 7200rpm mechanical storage, 4GB SLC NAND flash, and a 32MB cache.
With the Momentus XT series, Seagate is trying to bridge the gap between SSD performance (and price) and notebook hard drive capacity (and price), by adding 4GB of SLC NAND flash memory to a standard notebook hard drive. The drive uses an algorithm called Seagate Adaptive Memory to move the most frequently-accessed files to the NAND flash memory, so the drive should get faster as it tailors itself to each user’s demands. Maximum PC will publish a full review of the Momentus XT in an upcoming issue of the magazine, but we had a chance to run the drive through its paces.
We didn’t expect to see SSD-level speeds from this drive, and we didn’t. But our initial testing showed that the drive performed very well for a 2.5-inch mechanical drive and got better with repeated testing, a good indication that the adaptive algorithm was, well, adapting to our test procedures. Normally, a drive’s performance on the PCMark Vantage HDD subtest doesn’t vary much. But the Momentus XT’s first three runs averaged 5400 PCMarks, and the scores continued to rise until the drive stabilized around 6950 PCMarks—for reference, the average current-gen SandForce SSD gets around 35,000 and the latest Velociraptor, 7,500.
Seagate cautions that raw read/write benchmarks “are not a good measure of the actual performance benefit that an end user will experience,” but we’re including them anyway because that’s how we roll. 80MB/s average sustained reads and writes, while nowhere near SSD performance, are nothing to sneeze at in a 500GB drive. Random-access time varies sharply from .1ms (for files stored on the SLC NAND) to 17.3ms (for the rest).
The 500GB Momentus XT has an MSRP of $156, or about $75 more than a standard 500GB laptop drive. Of course, a typical SSD with half that capacity (but three times the speed) costs four times as much. At not much more than a standard 2.5-inch hard drive of the same capacity, we can see hybrid drives catching on in a big way.
Seagate Momentus XT
OCZ Vertex 2
HDTune Avg Sustained Read (MB/s)
HDTune Avg Sustained Write (MB/s)
HDTune Random Access Read (ms)
HDTune Random Access Write (ms)
HDTune Burst Read (MB/s)
HDTune Burst Write (MB/s)
HDTune 4KB Random Read IOPS
HDTune 4KB Random Write IOPS
Premiere Pro (sec)
PCMark Vantage x64 HDD Subscore
*Asterisk denotes random-access time for files on flash memory. All other files use second score. All drives tested on our hard drive test bench: A stock-clocked Intel i7-920 CPU on a Gigabyte GA-EX58-UD3R with 6GB DDR3, running Windows 7 Professional 64-bit. All tests performed using Intel southbridge SATA chipset with Windows 7 default AHCI drivers unless specified