Single page Print

Disk-intensive multitasking
TR DriveBench is a new addition to our test suite that allows us to record the individual IO requests associated with a Windows session and then play those results back on different drives. We've used this app to create a new set of multitasking workloads that should be representative of the sort of disk-intensive scenarios folks face on a regular basis.

Each workload is made up of two components: a disk-intensive background task and a series of foreground tasks. The background task is different for each workload, but we performed the same foreground tasks each time.

In the foreground, we started by loading up multiple pages in Firefox. Next, we opened, saved, and closed small and large documents in Word, spreadsheets in Excel, PDFs in Acrobat, and images in Photoshop. We then fired up Modern Warfare 2 and loaded two special-ops missions, playing each one for three minutes. TweetDeck, the Pidgin instant-messaging app, and AVG Anti-Virus were running throughout.

For background tasks, we used our Firefox compiling test; a file copy made up of a mix of movies, MP3s, and program files; a BitTorrent download pulling seven Linux ISOs from 800 connections at a combined 1.2MB/s; a video transcode converting a high-def 720p over-the-air recording from my home-theater PC to WMV format; and a full-disk AVG virus scan.

DriveBench produces a trace file for each workload that includes all IOs that made up the session. We can then measure performance by using DriveBench to play back each trace file. During playback, any idle time recorded in the original session is ignored—IOs are fed to the disk as fast as it can process them. This approach doesn't give us a perfect indicator of real-world behavior, but it does illustrate how each drive might perform if it were attached to an infinitely fast system. We know the number of IOs in each workload, and armed with a completion time for each trace playback, we can score drives in IOs per second.

DriveBench doesn't produce reliable results with Microsoft's AHCI driver, forcing us to obtain the following performance results with Intel's RST drivers. We couldn't get DriveBench to play nicely with our the X25-V RAID config, either, which is why it's not listed in the graphs below. The app will only run on unpartitioned drives, so we tested drives after they'd completed the rest of the suite.

Rather than busting out a series of value graphs for each DriveBench workload, we're just going to use the overall score, which is an average of the mean performance score in each multitasking workload.

The RealSSD and X25-M manage to pull ahead of the last-gen VelociRaptor in our value bar graph. They're the only SSDs to eclipse a mechanical drive here, though.

Moving to the scatter plot keeps the RealSSD in a positive light. The Crucial drive is quite a bit faster than most of the SSDs and doesn't command a hefty cost-per-gigabyte premium. The X25-M isn't too far behind, and it, too, has a sizable lead over the other contenders. You might want to avoid those 100GB SandForce drives, though. Their performance is at best good enough for fifth place, and even with the Agility, you're still paying more per gigabyte than the other SSDs.

Notice how all the mechanical drives have moved to the lower left-hand corner? They might be cheaper, but they're also a heck of a lot slower in our multitasking test.

Our IOMeter workloads are made up of randomized access patterns, presenting a good test case for both seek times and command queuing. The app's ability to bombard drives with an escalating number of concurrent IO requests also does a nice job of simulating the sort of demanding multi-user environments that are common in enterprise applications.

Since you're probably just about sick of graphs by now, we've consolidated our IOMeter scores with a single overall average. This score is the mean transaction rate across all load levels for the file server, web server, workstation, and database access patterns.

Finally, some redemption for the SandForce drives. The Agility, Vertex, and Force SSDs fare so well in IOMeter that even the 100GB drives find themselves near the front of the pack in our bar graph. Quelle surpris!

The SandForce SSDs are still more expensive on a cost-per-gigabyte basis, as the scatter plot nicely illustrates. However, the 100GB models offer higher transaction rates than the closest competition, which comes from the RealSSD C300. Interestingly, the F120 ends up getting the short end of the stick here. It's not fast enough to keep up with the 100GB SandForce drives and costs too much per gigabyte to be more attractive than the C300.

Making a case for anything but the Agility 2 or the RealSSD is pretty difficult here. They're just so much more appealing than the rest of the drives, including the X25-V array. And the mechanical drives? Well, they're back in the cheap-but-slow corner.