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SQLIOSim is "NOT" an I/O Performance Tuning Tool

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 

Bob Dorr
Senior SQL Server Escalation Engineer

Published Saturday, April 05, 2008 3:24 AM by psssql
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Comments

# Release for other HW platforms

Saturday, April 05, 2008 5:33 AM by JPolisel

Hi Bob,

SQLIO Disk Subsystem Benchmark Tool is such a great tool. In fact I was looking for this kind of tool for a while.

Do you have plans to release it for x64 and IA64 so I can take benchmarks on my new highend servers?

Thanks and regards,

JPolisel

# re: SQLIOSim is "NOT" an I/O Performance Tuning Tool

Thursday, April 10, 2008 2:23 PM by psssql

SQLIO and SQLIOSim are owned by the SQL Server development team and I don't know the status of X64 or IA64.  

For X64 you can run in the WOW and it is a valid test.   X64 supports 4K OS pages so actions such as scatter/gather I/O are safe from the WOW.   This is not the case from IA64.

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