This blog post is to again inform you "NOT" to consider SQLIOSim as an I/O performance evaluation tool! Every other month or so I get a rash of questions about using SQLIOSim to validate I/O performance and I have to repeat the same information.
As I have stated in other posts and documents SQLIOSim and SQLIOStress were designed to test the I/O stability not performance characteristics. SQLIOSim specifically includes random patterns as various stages of testing that will invalidate any performance comparison attempts. This even includes one SQLIOSim run to another.
SQLIOSim also includes segments of unbounded I/O attempting to to push memory and various queues to extreme depths. This too invalidates performance comparisons.
Don't consider SQLIOSim for performance benchmarking, instead use SQLIO Disk Subsystem Benchmark Tool: http://www.microsoft.com/downloads/details.aspx?familyid=9A8B005B-84E4-4F24-8D65-CB53442D9E19&displaylang=en
Senior SQL Server Escalation Engineer