You Got Flash In My Hard Drive

Even though hybrid hard drives have been on the market for the last four years, I've never met anyone that had a kind word for them. The first generation of hybrid hard drives were more like the accidental combination of peanut butter and chocolate bar in the old commercials than a polished Reese's cup. Seagate's new Momentus XT finally realizes some of the potential inherent in combining Flash and spinning disk in a single affordable package.

The old hybrid drives from Seagate and Samsung were doomed to failure for a number of reasons. First, they had just 256MB of MLC flash fronting a 5400RPM disk. MLC limited write performance, and since the small size made the Flash component smaller than the working set for an application like Photoshop or Final Cut, systems were going to the slow hard drive way too much. Finally, and most importantly, they relied on Windows Vista's ReadyBoost and other coding tricks to decide what data should go in the Flash.

Microsoft over emphasized boot-speed over improving application performance, so Windows DLLs were in Flash while application temp files spilled over to the slower disk.  Add in that Vista was generally despised by the kinds of geeks that try hot new disk tech and then convince their friends, families and employers to use it and hybrid drives never took off.

Seagate's new Momentus XT addresses these problems and delivers a nice mix of speed, power consumption and capacity. The new drives have 4GB of SLC flash setup as a cache so no operating system support is needed.  The Seagate folks say they specifically cache blocks that required head movement to access so the cache should speed up real world workloads by reducing the amount of head motion the drive has to do.

Seagate was kind enough to send me a pair of drives to play with, and like a kid on Hanukkah, the first thing I did was rip off the wrapping and stick one in my Macbook Pro. The Macbook badly needed a drive wipe and fresh installs of OS/X Parallels and Windows 7, so I took out the 497 little screws, changed the drive and put back 495. As usual, I had a few screws left over (or just loose), but the laptop felt way peppier than with the 5400RPM drive that was in there. In addition to speeding up my laptop, I wanted to run some real world benchmarks against the Momentus XT.I cloned the disk from the machine that until recently was my office desktop. With Windows Vista Ultimate and Windows XP in separate, heavily fragmented, partitions it seemed like a good platform for some benchmarking.  Of course, it wouldn't boot. I tried Clonezilla, Ghost and Acronis True Image all with the same results. I can say the Momentus vastly speeds up the blue screen of death memory dump. I had to reboot five times to see which driver was the culprit.

Once I got everything running, I wanted to see what the Momentus XT was good at.  Enterprise benchmarks like IOmeter work the whole drive evenly and show the Momentus XT to be about as fast as any other 7200RPM drive.  But laptop users don't work the drive evenly. They carry around all the files they may need but in a given day run PowerPoint, Excel or Photoshop. I decided to see how much faster my system with a hybrid drive could boot and load Photoshop (because I hate watching the plug-ins load).  After several boot cycles, my system would come up in roughly 20 seconds compared to 33 for the hard drive.  Photoshop would load in 9 seconds compared to 15 for the hard drive.My gut tells me that this hybrid technology is one of those cases where real world results are better than the benchmarks but only time will tell on that.  I also haven't gotten to putting the pair in a RAID-1 configuration and seeing how the caching works there.

Momentus XTs cost about twice as much as their flashless counterparts and about the same as a 64GB MLC SSD. Personally, I can't live with just 64GB on my laptop and would have to lay out $300 for a 128GB SSD, and even then I'd waste a lot of time on file maintenance as that little disk filled up.  When Seagate asks for them back, I think I'm going to buy one for the laptop myself.