How can I determine where my Windows Server 2012 is using Random or Sequential I/O operations when writing/reading the local SSD storage?

I have been asked to provide details to our hardware vendor on server usage in order to performance tune the server. They want to know if we are using Random or Sequential. The servers are running SQL Server 2012. I would like to be able to compile some stats and/or logs that show the various I/O operations to determine whether we are using random or sequential I/O and how much of each and when. I imagine this could be accomplished through some Performance Monitor counters or some other type of trace events. I hope this explains the situation better.

  • Can you clarify why you are asking this? Obviously it uses both. As it stands the question doesn't make a lot of sense. Downvoted due question unclear. – BlueCompute Dec 4 '14 at 15:46
  • I've updated the question. – Geoff Dawdy Dec 4 '14 at 17:07

On SSDs, sequential i/o is not at the same speed as random i/o, even though there are no moving parts. SSD drive specs shows that clearly.

Back to the original question, it is an inquiry whether the workload in action is x% sequential and y% random.

In the Linux world, there's a 'blktrace' utility that does it. In the Windows world, I'm currently on the lookout for now and will know soon. Heard from an SNDK Perf Engr that there's 'perfstat' so i'll validate that claim.


  • As SonnyD said, SSDs don't do Sequential IO at the same rate as Random, any benchmark will show this. – alex Jun 29 '15 at 21:15

I don't know any good tools, directly from the server. Instead, I'd recommend answering their question with a question- if you're doing IO to SSD, which has no moving parts and thus does sequential IO at the same speed as random IO, why do they care? Are they trying to size new storage for you that would be partly on regular disk?

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