IOMeter - RAID 5 - Transaction rate
Parity time. RAID 5 rounds out our IOMeter array segmentation, and we have results for three- and four-drive configurations.
And the nForce4 hits the wall again. Transaction rates for RAID 5 arrays on the nForce4 start to trail off as we hit four outstanding I/Os, and it's all over by the time we get to 16. That's really a shame since the nForce4 looks competitive at first.
To be fair, the ICH7R also hits a wall, but its performance doesn't start to plateau until the load reaches 64 outstanding I/Os. Since the Intel chip doesn't slow down at all with the web server test pattern, which is made up exclusively of read operations, it seems likely that the ICH7R's RAID 5 transaction rates are being constrained by write-related parity overhead.