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Seagate Momentus XT 750GB Hybrid Drive
Date: Nov 28, 2011
Author: Marco Chiappetta
Introduction and Specifications

Seagate’s first Momentus XT hybrid drive arrived about a year and a half ago. The original drive featured a 500GB hard drive paired to 4GB of SLC NAND flash and a SATA 3.0 interface. At the time of its release, the original Momentus XT turned out to be a rather compelling product. Its price was relatively low and Seagate’s adaptive memory technology “just worked”, which resulted in increased performance that was seamless to the end-user, regardless of the OS being used.

Today Seagate is ready to reveal its next iteration of the Momentus XT. The updated version of the drive we’ll be showing you here today features a 750GB storage capacity, with 8GB of SLC NAND flash, and a faster SATA 6.0Gbps interface. Much of the underlying technology is similar, but this new drive has more magnetic storage, more flash memory, a speedier interface, and its adaptive memory algorithms and hybrid data management tools--dubbed Fast Factor--have been tweaked for better real-world performance versus the original. Full specifications are below, with a performance profile to follow...

Seagate Momentus XT 750GB Hybrid Drive
Specifications & Features

The Seagate Momentus XT 750GB Drive

As we’ve mentioned, the Seagate Momentus XT 750GB drive features 8GB of integrated SLC NAND flash, linked to the traditional platter-based storage via an intelligent controller. The drive conforms to the standard 2.5” form factor with 9.5mm Z-Height, and sports a SATA 6.0Gbps interface. 32MB of DRAM cache is also incorporated into the drives, and they feature 7200RPM spindle speeds. Looking at the pictures above, there’s nothing that hints to the hybrid nature of the Momentus XT. They simply look like standard 2.5” hard drives. But, rest assured, they are very different.

Although Seagate hasn’t revealed all of the secret-sauce that makes the Momentus XT unique in the current market, understanding how the drive works is fairly straightforward. The 8GB of SLC NAND flash is used as a high-speed repository of sorts. The controller on the Momentus XT monitors usage patterns and copies the most frequently accessed bits of data from the hard drive to the solid state storage. And it all happens independent of the OS or drivers. According to Seagate, the data on the hard drives has to be accessed multiple times before it is copied to the solid state storage and the contents of the flash memory will dynamically and constantly change over time, based on usage. To put it simply, the most commonly accessed data on the platters gets copied to the much higher performing, SLC Flash memory, which results in a performance boost. And it’s not necessarily full files being copied, but rather the most frequently accessed bits of data. We should also point out that a new feature to the updated Momentus XT called Fast Boot uses a small portion of the solid state cache for data used during the boot process, which resides in a special location and won't change often, in order to maintain quick boot times.

Knowing how the adaptive memory on the Momentus XT works, reveals one of the drawbacks of a hybrid design such as this one—the flash memory will offer no performance benefit to infrequently accessed or new data. So, with large file copies, application installations, and the like, the Momentus XT will perform like a standard HD.
Test Setup and ATTO

Our Test Methodologies: Under each test condition, the drives tested here were installed as secondary volumes in our testbed, with a standard spinning hard disk for the OS and benchmark installations. Out testbed's motherboard was updated with the latest BIOS available as of press time and AHCI mode was enabled. Windows firewall, automatic updates and screen savers were all disabled before testing. In all test runs, we rebooted the system and waited several minutes for drive activity to settle before invoking a test.

HotHardware Test System
Intel Core i7 and SSD Powered

Processor -

Motherboard -

Video Card -

Memory -

Hard Drives -


Hardware Used:
Intel Core i7-2600K

Asus P8Z6-V Pro
(Z68 Chipset, AHCI Enabled)

NVIDIA GeForce GTX 285

4GB Kingston DDR3-1600

Seagate Momentus XT 750GB
Seagate Momentus XT
Seagate 7200.10 500GB + Intel 311
OCZ RevoDrive Hybrid (1TB)
Crucial M4 (256)

OS -
Chipset Drivers -
DirectX -

Video Drivers

Relevant Software:
Windows 7 Ultimate SP1 x64
Intel, iRST 10.5.1027
DirectX 11

NVIDIA GeForce 275.33

Benchmarks Used:
ATTO v2.47
CrystalDiskMark v3.01 x64
PCMark 7

ATTO Disk Benchmark
More Information Here: http://bit.ly/btuV6w

ATTO is a "quick and dirty" type of disk benchmark that measures transfer speeds across a specific volume length. It measures raw transfer rates for both reads and writes and graphs them out in an easily interpreted chart. We chose .5kb through 8192kb transfer sizes and a queue depth of 6 over a total max volume length of 256MB. ATTO's workloads are sequential in nature and measure raw bandwidth, rather than I/O response time, access latency, etc. This test was performed on blank, formatted drives with default NTFS partitions in Windows 7 x64.

Please note, the ATTO benchmark will not show the benefit of Seagate's adaptive memory technology. Rather, this benchmark shows somewhat of a worst-case scenario where the Momentus XT is limited in performance by its spinning hard disk platters.

The new Seagate Momentus XT offered better performance across the board in comparison to the original Momentus XT and was also faster than the HD integrated into the RevoHybrid. The standard SSD was much faster, however, as was the RevoHybrid when its solid-state cache comes into play.

CrystalDiskMark Benchmarks

CrystalDiskMark is a synthetic benchmark that tests both sequential and random small and mid-sized file transfers. It provides a quick look at best and worst case scenarios with regard to SSD performance, best case being larger sequential transfers and worse case being small, random transfers.

CrystalDiskMark Benchmarks
Synthetic File Transfer Tests

Like the ATTO benchmarks on the previous page, CrystalDiskMark DOES NOT benefit from Seagate's adaptive memory technology and characterizes only the performance of the Momentus XT's hard drive.

The numbers show the new Momentus XT 750GB drive offering about 10% better hard drive performance than the original Momentus XT. Intels' SRT technology, the standalone SSD, and the RevoHybrid once again offer better performance--as expected.

PCMark 7 Storage Benchmarks
We really like PCMark 7's Secondary Storage benchmark module for its pseudo real-world application measurement approach to testing. PCMark 7 offers a trace-based measurement of system response times under various scripted workloads of traditional client / desktop system operation. From simple application start-up performance, to data streaming from a drive in a game engine, and video editing with Windows Movie Maker, we feel more comfortable that these tests reasonably illustrate the performance profile of SSDs in an end-user / consumer PC usage model, more so than a purely synthetic transfer test.

Futuremark's PCMark 7 Secondary Storage

PCMark 7's storage benchmark, due to its psuedo-real-world workloads, does show the benefits of Seagate's adaptive memory technology. We ran this test three times to illustrate how the Momentus XT's performance scales from run to run as its solid state cache comes into play. The test was run  multiple times on the other hybrid solutions as well, and the results from their third runs are reported here. The other hybrid solutions, however, offered somewhat better performance in most of the tests.

As you can see, the Momentus XT's performance scales significantly as its solid state cache is utilized and the drive offers performance much better than a standard 7200RPM hard drive.
Our Summary and Conclusion

Performance Summary: The Seagate Momentus XT 750GB drive performed relatively well throughout our battery of tests. When its solid state cache comes into play, the Momentus XT is clearly faster than a standard hard drive and in some instances offers true “SSD-like” performance. The updated Momentus XT is also clearly faster than the first-gen drive due to its faster HD, increased solid-state cache and tweaked adaptive memory algorithms that react more quickly than the original’s. In comparison to other hybrid solutions, the Momentus XT competes favorably, but Intel’s Smart Response technology or options like the RevoDrive Hybrid are ultimately faster—sometimes much faster. Finally, compared to a standalone SSD, the Momentus XT trails in every facet of performance.

The Seagate Momentus XT

When we first took a look at the original Momentus XT mid-last year, we stated in our conclusion that, “While the Seagate Momentus XT doesn't clearly dominate all standard hard drives across every type of usage model, Seagate's hybrid implementation seems to address its intended markets quite well.” That statement is also true today, and the updated drive is definitely superior to the original in virtually every way. However, the storage landscape has changed dramatically since the original drive was released.

When the first Momentus XT hit the scene, it was offered for a cost of about $.31 per GB ($156 for the 500GB model). This new 750GB Momentus XT, despite offering a faster interface speed, double the amount of SLC NAND flash (4GB vs. 8GB), and tweaked adaptive memory algorithms, will debut with an identical cost per GB; the drive will sell for about $.31 per GB or $245 for the 750GB model. At the time of the original Momentus XT’s release though, sought-after SSDs were commanding upwards of $3.00 per GB. But today a good SSD can be had in the $1.20 to $1.75 per GB price range. And while hard drive prices have skyrocketed due to the tragic flooding in Thailand, it’s still possible to pick up a 500GB to 750GB, 7200RPM drive and a 120GB SATA III SSD for only slightly more than the cost of a Momentus XT. If you’ve got the right motherboard, using Intel’s Smart Response Technology can actually be cheaper when pairing a similar sized HD to a 20-40GB SSD cache. Using a standalone SSD for the boot volume and a hard drive for bulk storage will result in better performance, but is perhaps less elegant due to the need to manage both volumes, whereas a single hybrid solution is more seamless for the end-user. Regardless, the clear cost advantage the original drive had at launch has somewhat vanished.

That said, for users that can’t afford a larger capacity SSD and are limited to only a single drive configuration, like notebook or some HTPC users, for example, the Momentus XT can be a great fit. You’ll get a good amount of storage space and SSD-like performance in a single drive, with any OS and no special software or drivers to deal with.

  • Decent Value
  • Good Performance
  • SSD-Like Performance, HD-Like Price
  • OS Independent

  • Limited by performance of the HD when solid state cache not used
  • Outperformed by other hybrid solutions


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