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Seagate Momentus XT Solid State Hybrid Preview
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Date: May 24, 2010
Section:Storage
Author: Marco Chiappetta
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Introduction and Specifications

Solid State Drives are all the rage with PC Enthusiasts these days. Although relatively expensive in comparison to standard hard drives, Solid State Drives have gotten very popular and have earned a reputation as one of the most significant performance upgrades available to enhance general system responsiveness. Capacities are relatively low in comparison to standard hard drives, but access times and transfer rates are in a different league altogether. And it’s a good SSD’s quick access times and speedy transfers that dramatically impact the end user experience, for the better. Solid State Drives are simply different beasts versus traditional hard drives and the performance difference is easily perceptible to the end user.

Although there has been some noise over the years about hybrid drives that somewhat bridge the gap between hard drives and solid state drives, but they haven’t had a significant impact on the overall market. Hit your favorite on-line retailer and you’ll find a slew of SSDs and hard drives available, but nothing in between. If you need large amounts of storage space, a hard drive is a necessity (unless you’ve got an unlimited budget). But if it’s maximum performance you crave, only an SSD will do. Today, however, Seagate aims to change that with the release of the new Momentus XT Solid State Hybrid.

The Seagate Momentus XT mates 4GB of solid state storage with a traditional 2.5” hard drive in an attempt to bridge the current gap between hard drives and SSDs. Seagate claims the Momentus XT can offer the same kind of enhanced user experience as an SSD, but with the capacity and cost of a traditional hard drive. That’s a pretty tall order. Does the Momentus XT deliver? Let’s find out…

Seagate Momentus XT Hybrid Solid State Drive
Specifications & Features


Looking at the Seagate Momentus XT’s features and specifications, it’s only the “Solid State Memory” entry (second from the top) that reveals that this drive is somehow different than a traditional hard drive. Other than that, the Seagate Momentus XT’s specs read like those of a modern, 7200RPM, 2.5” SATA hard drive. And as you’ll see on the next page, it looks like a standard HD too.

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Seagate Momentus XT Hybrid

The Seagate Momentus XT will initially be available in three capacities—250GB, 320GB, and 500GB. The drive you see pictured below if the flagship 500GB model.

 
 
Seagate Momentus XT 500GB Hybrid Drive

The Seagate Momentus XT features 4GB of integrated SLC NAND flash, linked to the traditional platter-based storage via an intelligent controller. The drives conform to the 2.5” form factor with 9.5mm Z-Height, and they sport standard SATA 3.0Gb/s interfaces. 32MB of DRAM cache is also incorporated into the drives, and as we’ve already mentioned, 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 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 4GB 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 get's copied to the much higher performing, SLC Flash memory, which results in a performance boost.

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.

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Test System and IOMeter

 

Our Test MethodologiesUnder each test condition, the Solid State Drives tested here were installed as secondary volumes in our testbed, with a standard spinning hard disk for the OS and benchmark installations.  The SSDs were left blank without partitions wherever possible, unless a test required them to be partitioned and formatted, as was the case with our ATTO, Vantage, and CrystalDiskMark benchmark tests. And all drives were secure erased prior to the start of any testing. 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 Powered

Processor -

Motherboard -


Video Card -

Memory -


Audio -

Hard Drives -

 

Hardware Used:
Intel Core i7 965


Gigabyte GA-EX58-Extreme
(X58 Express Chipset)


GeForce GTX 280

6144MB Corsair DDR3-1333
CAS 7


Integrated on board

Seagate Momentus XT 500GB
Seagate 7200.11 1.5GB
WD Scorpio Blue 750GB
Patriot Memory Zephyr 128GB

OS -
Chipset Drivers -
DirectX -

Video Drivers
-


Relevant Software:
Windows 7 Ultimate
Intel 9.1.1.1025 w/ Matrix Storage
DirectX 11

NVIDIA ForceWare v196.34

Benchmarks Used:
HD Tach v3.0.1.0
ATTO v2.46
CrystalDiskMark v3
PCMark Vantage
SiSoftware Sandra 2010 SP1

IOMeter
I/O Subsystem Measurement

In the following tables, we're showing two sets of access patterns with IOMeter; one with an 8K transfer size, 80% reads (20% writes) and 80% random (20% sequential) access and one with IOMeter's default access pattern of 2K transfers, 67% reads and 100% random access. Both tests were conducted with 8 worker threades.

The adaptive memory technology of the Seagate Momentus XT doesn't seem to adapt to the workloads presented by IOMeter, as is evidenced by the similarity in the results between the first and third runs, but the drive does perform well, relative to the other hard drives we tested. With both the default and our workstation access patterns, the Momentus XT finishes well out in front of the other hard drives we tested. The SSD, however, dominates all around.

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SANDRA Testing

For our next set of tests, we used SiSoft SANDRA, the the System ANalyzer, Diagnostic and Reporting Assistant. Here, we used the Physical Disk test suite and provided the results from our comparison SSDs. The benchmarks were run without formatting and read and write performance metrics are detailed below. We have also included SANDRA's detailed graph so you are able to see how the drive performs over time along with the average rated result.
     

SiSoft SANDRA 2010
Synthetic Benchmarks


Seagate Momentus XT
(Read)
 


WD Scorpio Blue
(Read)
 


Seagate Barracuda 7200.11
(Read)


Patriot Zephyr 128GB
(Read)

The Seagate Momentus XT performs like a standard hard drive in the SiSoft SANDRA Physical Disk benchmark. It finished about 1MB/s ahead of the WD Scorpio Blue in terms of Read bandwidth.
 


Seagate Momentus XT
(Write)
 


WD Scorpio Blue
(Write)
 


Seagate Barracuda 7200.11
(Write)


Patriot Zephyr 128GB
(Write)

 

SANDRA's physical disk write performance test has the Seagate Momentus XT finishing well behind the WD Scorbio Blue. We must point out, however, that this benchmark will not fully exploit the benfits of the hybrid solid state storage available on the Momentus XT. Although the spiky write performance inidicates the solid state storage is being accessed.

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ATTO Disk Benchmark

ATTO is a more straight-forward type of disk benchmark that measures transfers 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 over a total max volume length of 256MB.  This test was performed on blank, formatted drives with NTFS partitions.

ATTO Disk Benchmark
Version 2.46


Seagate Momentus XT
 


WD Scorpio Blue
 


Seagate Barracuda 7200.11


Patriot Zephyr 128GB

 

The Seagate Momentus XT performed somewhere in between the WD Scorpio Blue and the Barrcuda 7200.11 in the ATTO Disk Benchmark. The true solid state drive, however, was in a league of its own. But again, we must reiterate, a low-level benchmark like ATTO that simply tests bandwidth with varying block sizes, will not benefit from the adaptive memory technology incorporated into the Momentus XT.

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CrystalDiskMark Benchmarks

CrystalDiskMark is another synthetic test we've started looking at that evaluates both sequential as well as random small and large file transfers.  It does a nice job of providing a quick look at best and worst case scenarios with SSD performance, best case being large sequential transfers and worse case being small, random 4K transfers.

CrystalDiskMark Benchmarks
Synthetic File Transfer Tests


Seagate Momentus XT
 


WD Scorpio Blue
 


Seagate Barracuda 7200.11


Patriot Zephyr 128GB

CrystalDiskMark tells a similar story to ATTO.  Here, the Momentus XT finishes in between the Scorpio Blue and Barracuda once again, but well behind the SSD. In a strict comparison between WD's fastest mobile HD though, despite the fact that CrystalDiskMark does not exploit the Momentus XT's adaptive memory technology, the Momentus XT puts up significantly better numbers in every workload.

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HD Tach Testing

 

Simpli Software's HD Tach is described on the company's web site as such: "HD Tach is a low level hardware benchmark for random access read/write storage devices such as hard drives, removable drives, flash devices, and RAID arrays. HD Tach uses custom device drivers and other low level Windows interfaces to bypass as many layers of software as possible and get as close to the physical performance of the device being tested."

HD Tach v3
http://www.simplisoftware.com/


Seagate Momentus XT
 


WD Scorpio Blue
 


Seagate Barracuda 7200.11


Patriot Zephyr 128GB

HD Tach is another benchmark that doesn't truly benefit from the Momentus XT's adaptive memory technology. But while the drive's transfer speeds are in-line with similar hard drives according to this test, its access time is more on par with the SSD. Of course, the .3ms access time reported for the Momentus XT is representative of the solid state storage partition's performance and not if its spinning platters, but it hints at the benefits of the Momentus XT's adaptive memory technology.

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PCMark Vantage

Next we ran the three drives through a battery of tests in PCMark Vantage from Futuremark Corp. We specifically used only the HDD Test module of this benchmark suite to evaluate all of the drives we tested. Feel free to consult Futuremark's white paper on PCMark Vantage for an understanding of what each test component entails and how it calculates its measurements. For specific information on how the HDD Test module arrives at its performance measurements, we'd encourage you to read pages 35 and 36 of the white paper.

Futuremark's PCMark Vantage
http://www.futuremark.com

We really like PCMark Vantage's HDD Performance for its real-world application measurement approach to testing.  From simple Windows Vista start-up performance to data streaming from a disk drive in a game engine and video editing with Windows Movie Maker, we feel confident that these tests best illustrate the real performance profile of our SSDs in an end user/consumer PC usage model.

 

Here is where things start to get really interesting. The HDD Test suite incorporated into PCMark Vantage represent a pseudo-real world secenario with which the Momentus XT's adaptive memory technology can be exploited. In this graph and the one on the next page, there are two sets of results for the Momentus XT representing the first and third runs of the benchmark on the drive.

As you can see, in the first run, where the Momentus XT hasn't had a chance to adapt to the workload, it performs somewhat better than the WD Scorpio Blue. By the third run, however, the Momentus XT had adapted and its performace skyrockets as a result.

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PCMark Vantage (Cont.)

Our next series of Vantage tests will stress the write performance. Applications like video editing, streaming and recording are not what we would call a strong suit for the average SSD, due to their high mix of random write transactions.  We should also note that it's not so much a weakness of the memory itself, but rather the interface and control algorithms that deal with inherent erase block latency of MLC NAND flash.  SSD manufacturers are getting better at this, as is evidenced by our results below...

Futuremark's PCMark Vantage
http://www.futuremark.com

 

The trend continued in the remainder of the PCMark Vantage tests. On the first run of the benchmark, the Seagate Momentus XT performed surprisingly well. By the third run though, performace had increased dramatically and approached the level of the true SSD.

We should also point out that we ran this test numerous times, and after the third run, the additional performance increases stopped, which is to say Run 4 performed like Run 3. The screenshots of the actual Vantage performance summaries are available in the image gallery at the bottom of the page for those that would like to see the progression from Run 1 through Run 4.

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Our Summary and Conclusion

Performance Summary: The Seagate Momentus XT produced some interesting performance results. In the purely synthetic tests designed to look at raw throughput, the Momentus XT generally performed like a high-end, 7200 RPM hard drive--transfer rates typically fell between the WD Scorpio Blue and Seagate Barracuda desktop drive. In the system level benchmarks like those employed in PCMark Vantage, however, once the Momentus XT's adaptive memory technology learned the usage patterns and copied over the most commonly accessed bits of data to the solid state portion of the drive, performance improved dramatically. The Momentus XT was never able to truly match the performance of a true SSD, but its performance when the adaptive memory technology was used was far superior to a standard HD.


Although our benchmarks tell an interesting story, there is still a little more to discuss. Prior to evaluating the retail-ready version of the Momentus XT featured in this article, we had the opportunity to experiment with an alpha version of the drive. The benchmarks with the alpha version of the drive looked much like the ones presented here, but with the alpha drive we had enough time to experiment for a few weeks with the drive acting as a primary boot volume, with an full OS install, etc. It is difficult to say that all of the performance benefits we experienced were due to the drive itself, because Windows 7 also adapts somewhat to usage patterns, but the Seagate Momentus XT seemed to speed up the system, bit by bit, over time. Boot times, application launching, and web browsing in particular performed better after using the Momentus XT for a while, than when the OS was first installed.

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 performance result quite well. We would need to spend much more time evaluating final retail product to truly pass judgment on the effective of Seagate's adaptive memory approach to see how it reacts to being nearly full / cluttered for an extended period, littered with apps and media, etc. However, it seems Seagate is definitely on to something.

The initial three drives in the Seagate Momentus XT line-up will retail for $156 (500GB), $132 (320GB), and 250GB ($113). Those prices equate to roughly $0.31 to $0.45 per gigabyte, which puts these drive within striking distance of a standard HD in terms of price and much less expensive than any SSD. Considering the excellent performance of the Momentus XT when its on-board flash memory comes into play, we're impressed with what these drives have to offer.

If you'd like to learn more about the Momentus XT, Seagate and Asus will be hosting a webcast tomorrow, that's open to the public. And they're going to give away a trio of systems equipped with Momentus XT drives. "On Wednesday, May 26, at 11 a.m. PST, Seagate and OEM customer ASUS will co-sponsor a live webcast unveiling not only the new Seagate Solid State Hybrid drive, Momentus XT, but also featuring the new ASUS ROG G73JH system with two Momentus XT drives. Three lucky attendees of this webcast will win a new G73 system just for attending." Those of you that are interested in attending can do so, by
registering at this link.

 

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

 

  • Solid State Storage Not Always Used
  • Largest Drive "Only" 500GB

 



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