We got the first hints that Seagate was planning a hybrid hard drive when, in response to an offhand question last year, company reps replied with “no comment,” instead of saying “hybrid drives are deeeaaaad!” as we expected. Our suspicions were confirmed when we got our hands on the Momentus XT, a 500GB 7,200rpm notebook drive with 4GB of SLC NAND flash memory and an “Adaptive Memory” algorithm designed to speed up your system by copying the most frequently accessed files to the NAND flash.
By adding a small amount of high-speed flash memory to a standard mechanical drive, Seagate hopes to hit the middle-ground between solid-state speed and mechanical price and capacity. Under the hood, the Momentus XT is virtually identical to the non-hybrid 500GB Momentus 7200.4, with three key additions: a 32MB DRAM cache instead of 16MB, 4GB of SLC NAND, and the Seagate Adaptive Memory algorithm to make sense of it all.
It's like a mechanical hard drive, but better. And more expensive.
Rather than trying to speed up the whole disk, Adaptive Memory moves the most frequently used files to the NAND for faster access time. So we won’t see massive raw-speed improvements in the first sectors of the disk like we did with Silverstone’s DIY hybrid HDDBoost, but instead should see considerable improvements in day-to-day tasks.
Indeed, in our low-level drive benchmarks like HDTune, the Momentus XT was mostly indistinguishable from a current-gen Momentus 7200.4. We did see decent improvements in burst speeds, and massive improvements in random-access times for files present on the NAND flash—1.9ms read access times and 1.2ms write access times versus 16.5ms on the Momentus 7200.4. HDTune read and write IOPS also benefitted from the SLC NAND, with 4KB random-read IOPS at nearly 2,500, versus just 60 on the mechanical drive. This, of course, is due to the flash memory and is not present across the whole disk.
But if raw numbers don’t tell the full story for the Momentus XT, what does? Real-world benchmarks, of course! After a few iterations to allow Adaptive Memory to get the hang of our Premiere Pro encoding benchmark, the XT turned in results that were 5 percent faster than the 7200.4.
The most impressive part of the Barracuda XT, though, was its performance in PCMark Vantage’s HDD subtest, which tests hard drive performance over a series of real-world tasks. Our first run yielded a subscore of around 4,500, which is nothing to write home about—it’s the same as a standard Momentus drive. But subsequent scores kept going up. And up, and up, until the Momentus XT’s HDD subscore leveled off at 9,300 PC Marks—not exactly current-gen SSD levels, but faster than any mechanical hard drive has the right to be.
What does that mean? The drive works. Its base performance is every bit as good as a fast 500GB mechanical hard drive, and for your most frequently used files (including system files, hooray!), it’s substantially better. And considering that it’s only $50 more than a standard 7,200rpm Momentus drive, it’s a good upgrade before the giant step to an SSD.
Seagate Momentus XT 500GB Hybrid Drive
Adaptive Memory works; considerably speeds up most-accessed files; competitive price.
More NAND would be better.
Seagate Momentus XT
Seagate Momentus 7200.4
OCZ Vertex 2 (3Gb/s)
Avg Read (MB/s)
Random-Access Read (ms)
Burst Read (MB/s)
Avg Write (MB/s)
Random-Access Write (ms)
Burst Write (MB/s)
4KB Read (IOPS)
4KB Write (IOPS)
IOMeter Random-Write IOPS (4KB, Queue Depth 32)
Premiere Pro (sec)
PCMark Vantage HDD
Best scores are bolded. All drives tested on our hard drive test bench: a stock-clocked Intel i7-930 CPU on an Asus P6X58D Premium motherboard with 6GB DDR3, running 64-bit Windows 7 Professional. All 3Gb/s tests performed using latest Intel ACHI drivers; all 6Gb/s tests use onboard Marvell 9123 6Gb/s SATA controller with latest drivers.