Our testing methods
If you're unfamiliar with The Twins, our new duo of storage test platforms, I recommend checking out this page from our recent VelociRaptor VR200M review. These systems pack potent hardware and have been furiously testing hard drives and SSDs for weeks now. Unfortunately, Intel still hasn't resolved the performance scaling issue we found in its latest storage controller drivers for the P55 chipset. As a result, The Twins are still running the Microsoft AHCI driver built into Windows 7.

Before dipping into pages of benchmark graphs, let's set the stage with a quick look at the players we've assembled to take on the X25-V. Below is a chart highlighting some of the key attributes that can affect drive performance.

The X25-V will do battle with a slew of SSDs based on a range of different controllers from Indilinx, Intel, JMicron, Marvell, and Toshiba. All of those drives cost about three times what you'll pay for the X25-V—an important consideration to keep in mind when looking at the test results on the following pages.

What about newer SSDs like Crucial's RealSSD C300 and all that SandForce-based hotness that was on display at CES? Well, I've actually been busy testing a trio of SandForce-based drives. We should have a review of those published very soon. As for the C300, it's been sitting on the shelf awaiting a firmware update to address performance issues. That firmware update has finally been released, and by the time you read this, the RealSSD should be mid-way through our test suite.

For some additional perspective, we've included performance data from a trio of mechanical hard drives. Western Digital's 10k-RPM VelociRaptor VR200M is the fastest mechanical hard drive that plugs into a Serial ATA interface, so it has perhaps the best chance of challenging SSDs on the performance front. We've also added the original VelociRaptor VR150M to the mix, since it still has quicker access times than most desktop drives. Finally, we've thrown in a two-terabyte Caviar Black to represent the best performance 7,200-RPM mechanical drives have to offer.

Since the X25-V is relatively inexpensive, we couldn't resist combining two of them in a RAID 0 array for some additional testing. Besides, it would have been cruel to pit the budget X25-V against a stack of more expensive competitors without throwing the value drive a bone. We crafted our array using the Serial ATA RAID controller built into Intel's P55 chipset. The array was configured with a 128KB stripe size—the default in Intel's RAID BIOS—and we used the company's 9.6.0.1014 Rapid Storage Technology drivers. Unfortunately, although the Intel drivers support TRIM on SSDs acting as single drives, they can't pass the command to solid-state drives that are members of a RAID array. We have yet to encounter a RAID controller that claims to support TRIM for SSDs running in RAID.

The lack of TRIM support could prove problematic for our RAID config given how much the block-rewrite penalty inherent to flash memory can curtail long-term SSD performance. This penalty and the TRIM command designed to offset it both complicate our testing somewhat, so I should explain our SSD testing methods in greater detail. Before testing the drives, each was returned to a factory-fresh state with a secure erase, which empties all the flash pages on a drive. Next, we fired up HD Tune and ran full-disk read and write speed tests. The TRIM command requires that drives have a file system in place, but since HD Tune requires an unpartitioned drive, TRIM won't be a factor in those tests.

After HD Tune, we partitioned the drives and kicked off our usual IOMeter scripts, which are now aligned to 4KB sectors. When running on a partitioned drive, IOMeter first fills it with a single file, firmly putting SSDs into a used state in which all of their flash pages have been occupied. We deleted that file before moving onto our file copy tests, after which we restored an image to each drive for some application testing. Incidentally, creating and deleting IOMeter's full-disk file and the associated partition didn't affect HD Tune transfer rates or access times.

Our methods should ensure that each SSD is tested on an even, used-state playing field. However, differences in how eagerly an SSD elects to erase trimmed flash pages could affect performance in our tests and in the real world.

With few exceptions, all tests were run at least three times, and we reported the median of the scores produced. We used the following system configuration for testing:

We used the following versions of our test applications:

• WorldBench 6
• Intel IOMeter 2006.07.27
• Xbit Labs File Copy Test 0.3
• HD Tune 4.01
• Visual Studio 2008 with 03-23-2010 Firefox source
• Call of Duty: Modern Warfare 2
• Crysis Warhead

The test systems' Windows desktop was set at 1280x1024 in 32-bit color at a 75Hz screen refresh rate. Vertical refresh sync (vsync) was disabled for all tests.

Most of the tests and methods we employed are publicly available and reproducible. If you have questions about our methods, hit our forums to talk with us about them.