Meausuring QD in win7

[Ao1]

A run of AS Benchmark shows a correct correlation of qd with that shown on the Win 7 Disk Resource monitor.

Most desktop systems have less than 1 outstanding IO during normal operation, but under heavy multitasking you can see the IO queue depth hit 4 or 5 IOs for writes. Going much above that and you pretty much have to be in a multi-user environment, either by running your machine as a file server or by actually running a highly trafficked server. Source: AandTech

100% random writes, IO queue depth 1 4KB 16KB 32KB 64KB 128KB
OCZ Core (JMicron, MLC) latency = 244ms 243ms 241ms 243ms 247ms

The real issue is the small random write access penalty that can be a problem even at qd1 as can be seen above or as highlighted here