Seagate's Momentus XT hybrid drive worth the money

The SSD/HDD combo has good read rates, excellent data write performance

Seagate Technology this month offered up its second attempt at a drive that combines NAND flash storage capacity with traditional magnetic spinning disk media. The goal is simple: better performance at a lower cost.

Seagate has yet to put out a consumer-class solid state drive (SSD), so this is its closest attempt to hit the attributes that have made SSDs popular in the last couple of years.

The first attempt failed miserably. The Momentus 5400 PSD, or Power Savings Drive had a spindle speed of 5,400rpm and only 256MB of NAND flash capacity. (Seagate had placed its marketing bullseye on power savings, not performance.) The fact is, even a full-fledged SSD doesn't deliver power savings for consumer-type products that's worth writing home about, so charging extra for the Momentus 5400 PSD didn't go over well.

In contrast, the Seagate Momentus XT is a 7200rpm Serial ATA hard disk drive that adds 4GB of SSD capacity and 32MB of DDR3 cache memory to boost performance on several levels.

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The Momentus TX with rear cover removed

Oddly, Seagate never offered its own benchmark test results on the Momentus XT when it arrived. But, the company talked a lot about performance, so I was looking forward to testing the drive's read/write and boot times. My hope was that the XT would match SSD read/write speeds and offer consumers a lower-cost option to flash drives.

What I found is that the XT doesn't match today's popular SSDs for read speeds, or most SSDs when it comes to write performance. It does come close to today's fastest hard disk drives for read speeds and it beats them -- as well as some SSDs - on write performance -- and, more importantly, on price.

For my tests, I used a Dell Latitude D830 laptop with a 2.4-GHz Intel Core 2 Duo processor running Windows XP Professional SP2. I load a full compliment of applications on the laptop, such as Adobe Photoshop, AOL Instant Messenger, Windows Office Professional 2007 and Excel, along with a slew of file folders, in order to add reality to the test bed.

Performance tests

Mark Wojtasiak, senior product marketing manager at Seagate, said the company's own tests showed that their Momentus XT boots within five seconds of an SSD's boot time, and is 15 seconds faster than Western Digital's 300GB Velociraptor drive. That statement is accurate.

I found the boot-up time for this drive pretty impressive - 18 seconds. But it lagged on reboot, which took 43 seconds. Overall, though, these times compare favorably with other SSDs and hard drives I've tested (see results below).

To test read/write speeds, I used several benchmarking tools, starting with ATTO Disk Benchmark Software. The Seagate Momentus XT showed a read speed of 96MB/sec, with a standout write speed of 92MB/sec.

Next, I tested the new drive with Simpli Software Inc.'s HD Tach benchmark software. Those tests showed an average read speed of 83.7MB/sec, a burst speed of 213MB/sec, a random access time of .3 milliseconds and a CPU utilization rate of 8%.

I also tested the Momentus XT with the HD Tune 2.55 hard disk utility, which reported an average data transfer speed of 78.6MB/sec, a data transfer burst rate of 123.3MB/sec, an access time of 16.5 milliseconds and a CPU utilization rate of 4.3%.

By comparison, Western Digital's fastest hard drive, the VelociRaptor VR200M (600GB model) model, has a 145MB/sec. read rate and an 82MB/sec. write rate, with a random data access time of about 7 milliseconds. (The company's earlier 300GB VelociRaptor model had a 110MB/sec. read rate and 81MB/sec. write rate, with a random data access time of about 10 milliseconds.)

To test the Momentus XT drive's write speed with a real-word application, I copied a 2GB file folder with 544 .jpg images from the desktop to the My Documents folder, which was completed in a fast 35 seconds, just 9 seconds longer than it took Intel's X25-M SSD to transfer the same folder. The Seagate may have takena bit longer, but it costs hundreds of dollars less than the X25-M SSD and offers hundreds of gigabytes more storage.

Although it's been touted as a hard drive with SSD speed, the Momentus XT can't really meet or beat a full-fledged SSD on read performance. For example, I tested OCZ's Apex SSD with ATTO's benchmark utility and it showed a 221MB/sec sequential read rate and 160MB/sec sequential write rate. The Intel X25-M SSD, considered by many the standard in consumer-class SSDs, clocks in with an average read speed of 190MB/sec. and a 70MB/sec write rate.

Price advantage: Momentus XT

But here's the rub. The Agility Apex SSD with 60GB costs $159 at online retail sites, such as Newegg.com. The Intel X25-M SSD with 80GB of capacity costs about $215 retail. Even Intel's most affordable SSD, the X25-V, retails for $125, but you're only getting 40GB of capacity.

The Momentus XT with 250GB of capacity costs just $113, and a 500GB model goes for $156. So you are getting top hard drive read performance and even better write performance than some SSDs at a very reasonable price.

Compared to a top-performance traditional hard drive, such as Western Digital's VelociRaptor VR200M, Seagate still wins. The 450GB VelociRaptor VR200M retails for $299, the 600GB model, for $329.

A standard VelociRaptor with 150GB of capacity, sells for $185 at Newegg.com.

The VelociRaptor, with a 10,000rpm spindle speed, is considered by most to be the fastest consumer hard drive on the market. But, the Momentus XT's platter rotates at 7,200rpm, and still beats the VelociRaptor for write speeds. So you can see how that drive's SSD really can boost performance.

It bears noting that I did not test the Momentus XT for its affect on the laptop's battery life. After testing more than a dozen SSDs for this, I've found very little difference between a hard drive and an SSD.

Overall, I like the Momentus XT for several reasons. It is a very fast drive, particularly for data writes, and it has a very attractive price that is likely to only get better as Seagate ramps up sales. Would I recommend this for a tablet or other device that would be left running while in transport? No. In the end, it's still a hard drive with an actuator arm that can damage a disk platter if bumped hard. But I would not hesitate to buy this drive for my laptop for the faster boot-up times, application loads and overall better performance.

Functional Drive Data Comparison

  Capacity Buffer size Spindle speed Interface
Intel X25-M 160GB NA NA SATA 3.0Gb/sec.
OCZ Apex 120GB NA NA SATA 3.0Gb/sec.
Seagate Momentus XT 320GB 32MB 7,200rpm SATA 3.0Gb/sec.
Western Digital Velociraptor HDD 300GB 16MB 10,000rpm SATA 3.0Gb/sec.

HD Tach Throughtput Speed Tests

  Burst Speed Average Read Random Access CPU Utilization
Intel X25-M 230.7/sec. 190.3 0.1ms 12%
OCZ Apex 219MB/sec. 156.6MB/sec. 0.2ms 7%
Seagate Momentus XT 213MB/sec. 83.7MB/sec. 0.3ms 8%
Western Digital Velociraptor HDD 250.3MB/sec. 105.6MB/sec. 7.0ms 2%

Boot-up Times (in seconds)

  Cold Boot Restart
Intel X25-M 00:17 00:21
OCZ Apex 00:22 00:25
Seagate Momentus XT 00:18 00:43
Western Digital Velociraptor HDD NA NA
Testing software: Simpli Software HD Tach

Lucas Mearian covers storage, disaster recovery and business continuity, financial services infrastructure and health care IT for Computerworld. Follow Lucas on Twitter at @lucasmearian or subscribe to Lucas's RSS feed . His e-mail address is lmearian@computerworld.com.

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