OCZ's Vertex 2 Pro Preview: The Fastest MLC SSD We've Ever Testedby Anand Lal Shimpi on December 31, 2009 12:00 AM EST
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SandForce’s Achilles’ Heel
I surmised that SandForce’s DuraWrite technology would only be able to reduce the number of flash writes on data that was easily compressible. Documents, libraries, executables, as evidenced by the Windows 7 + Office 2007 install achieving a very low write amplification of 0.44x.
To see how bad the drive’s performance would suffer if we dealt primarily with compressed files I created a test that exclusively copied compressed files to the drive - MP3s, JPGs, x264s, RARs and DivX movies. I wrote roughly 20GB of compressed data to the drive and measured average IOs per second and disk bandwidth.
|OCZ Vertex 2 Pro 100GB||241 IOPS||145.9 MB/s|
|OCZ Vertex 256GB||181 IOPS||181.5 MB/s|
|Intel X25-M G2 160GB||110 IOPS||109.9 MB/s|
While the Vertex 2 Pro achieves a competitive average IOPS, its effective bandwidth is actually lower than the older Indilinx based Vertex SSD. What this tells us is that some of those write requests took much longer to complete on the Vertex 2. It’s akin to having two video cards with the same average frame rate, but one with a much lower minimum frame rate.
I wouldn’t characterize its performance as unacceptable by any means. Remember this is pre-production hardware and it’s still faster than X25-M G2 thanks to Intel’s ~100MB/s write limit. What it does show however is a weakness in the DuraWrite technology. Presumably the majority of your file writes aren’t going to be compressed files so your performance shouldn’t be gated by this issue, even then I’ve shown that you shouldn’t be any worse off than you would be with Intel’s X25-M.