Seagate Momentus XT hybrid SSD boots into a new dimension

In InfoWorld tests, OS boot times proved twice as fast, and Word and Excel loaded in just three or four seconds

When the Seagate folks asked me if I wanted to try out their new hybrid drive, my jaw dropped. I'm no stranger to the concept: IBM mainframes had hybrid drives decades ago, but the IBM drive was the size of a Volkswagen Beetle and cost as much as a Mercedes Benz. Seagate's version costs just $156 for 500GB of disk and a 4GB SSD (solid-state drive), and it fits in a laptop. Not only that, but it is operating system independent: The NAND flash memory is directly integrated into the drive controller board and does not require any specific software to be loaded on the operating system.

Other drive vendors such as SilverStone are shipping what is in essence an SSD front-end cache in a 3.5-inch drive tray, but the SilverStone product is strictly a cache and doesn't seem to have any sort of adaptive technology. Another vendor, Raidon, offers an SSD that seems to serve as a read cache, since the SSD in this case mirrors what's on the spinning platters. Both are good efforts, but they leave me wanting.

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Seagate's product isn't just a hard disk with a 4GB SSD cache -- the SSD is adaptive, meaning it keeps tabs on your most frequently used data in order to serve it up in an instant. Seagate's NDA briefing stressed that the first time you try to load anything from the hybrid drive, you won't see any difference in speed from any other 7,200-rpm disk drive. However, each subsequent load will get faster and faster. How much faster? Mileage will of course vary, but Seagate claims as much as 40 percent. Naturally, I ran my own tests to find out.

Considering just how many folks use Microsoft Office, I figured that Microsoft Word 2008 on my MacBook Pro with the original hard disk would serve as a good baseline. Even before I swapped in the hybrid drive, my tests showed that application load times shortened with each subsequent launch, going from 23.30 seconds on the first load to 12.35 on the second to around 2.76 for each load after that. Clearly, either Microsoft or Mac OS X was already doing some sort of caching, so to gauge the true effect of the SSD caching, I shut down the MacBook Pro between tests.

The results, as you can see in the table below, are impressive. Mac OS X boot times were cut in half. After two loads, Word was launching twice as fast as on the original drive. By the fifth launch, both Word and Excel were loading four to five times faster. Just imagine launching Word or Excel in three or four seconds -- it's shockingly fast.

Time will tell how the Momentus XT fares in day-to-day use. One word of caution: Go with a fresh OS install. It seems that copying a clone of a disk to the Momentus XT may result in performance actually degrading. I'll have more to report on that in a later post.

I've been lusting after SSDs since they arrived for laptops but couldn't bring myself to blow that kind of money. Considering the price and performance of the Momentus XT, however, I expect I'll be upgrading a whole lot of my gear in the near future. As for power and heat, the Seagate engineers tell me that it's a wash. At least my lap won't get any hotter.

Seagate Momentus XT hybrid vs. hard drive

  First load Second load Third load Fourth load Fifth load
OEM HDD boot times 56.341.02.7044.5359.7549.55
Momentus XT boot times 38.0723.2824.6925.8224.58
Word 2008 on OEM HDD 15.613.517.3212.3217.77
Word 2008 on Momentus XT 12.7510.558.434.24.09
Excel 2008 on OEM HDD 14.5810.9513.9514.2118.63
Excel 2008 on Momentus XT 3.523.433.613.523.37

Testing notes: Times are in seconds. I used a stopwatch to measure program load times, so one must take into account human reaction time. I would say that the margin for error on this test was plus or minus half a second. The MacBook Pro is a 17-inch model with 2.5GHz Core 2 Duo processor and 4GB of RAM. The original (OEM) hard disk is a Hitachi 250GB SATA, 5,400-rpm, 8MB cache (model HTS542525K9SA00). The Seagate Momentus XT is a 500GB SATA, 7,200-rpm, 32MB cache, and 4GB SLC NAND flash memory.

This story, "Seagate Momentus XT hybrid SSD boots into a new dimension," was originally published at Follow the latest developments in storage and read InfoWorld Test Center product reviews at