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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.

Interface speed Spindle speed Cache size Platter capacity Total capacity
Caviar Black 2TB 3Gbps 7,200 RPM 64MB 500GB 2TB
Nova V128 3Gbps NA 64MB NA 128GB
PX-128M1S 3Gbps NA 128MB NA 128GB
SiliconEdge Blue 3Gbps NA 64MB NA 256GB
SSDNow V+ 3Gbps NA 128MB NA 128GB
VelociRaptor VR150M 3Gbps 10,000 RPM 16MB 150GB 300GB
VelociRaptor VR200M 6Gbps 10,000 RPM 32MB 200GB 600GB
X25-M G2 3Gbps NA 32MB NA 160GB
X25-V 3Gbps NA 32MB NA 40GB

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 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:

Processor Intel Core i5-750 2.66GHz
Motherboard Gigabyte GA-P55A-UD7
Bios revision F4
Chipset Intel P55 Express
Chipset drivers Chipset
Memory size 4GB (2 DIMMs)
Memory type OCZ Platinum DDR3-1333 at 1333MHz
Memory timings 7-7-7-20-1T
Audio Realtek ALC889A with 2.42 drivers
Graphics Gigabyte Radeon HD 4850 1GB with Catalyst 10.2 drivers
Hard drives Western Digital VelociRaptor VR200M 600GB
Western Digital Caviar Black 2TB
Western Digital VelociRaptor VR150M 300GB
Corsair Nova V128 128GB with 1.0 firmware
Intel X25-M G2 160GB with 02HD firmware
Intel X25-V 40GB with 02HD firmware
Kingston SSDNow V+ 128GB with AGYA0201 firmware
Plextor PX-128M1S 128GB with 1.0 firmware
Western Digital SiliconEdge Blue 256GB with 5.12 firmware
Power supply OCZ Z-Series 550W
OS Windows 7 Ultimate x64

We used the following versions of our test applications:

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.