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Brad, I appreciate your work! I do have a question though.
With respect to monitoring SAN activity via an OS source (perfmon/sysmon), a while back I was discouraged from relying on anything but expensive proprietary SAN software - likely by a vendor. As a government DBA managing a couple thousand SQL instances, I'm always trying to save your money. If you have a moment, would you mind speaking or linking to that apparent misdirection?
Again, many thanks, Patrick
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currym (6/6/2011)
Brad, I appreciate your work! I do have a question though. With respect to monitoring SAN activity via an OS source (perfmon/sysmon), a while back I was discouraged from relying on anything but expensive proprietary SAN software - likely by a vendor. As a government DBA managing a couple thousand SQL instances, I'm always trying to save your money.  If you have a moment, would you mind speaking or linking to that apparent misdirection? Again, many thanks, Patrick
Not all of the built-in IO-related performance monitor counters work well if SQL Server is using a SAN for data storage, although some of them do. Two articles that discuss this topic (and their are many more) include:
http://msdn.microsoft.com/en-us/library/cc966412.aspx http://www.sqlskills.com/BLOGS/PAUL/post/How-to-examine-IO-subsystem-latencies-from-within-SQL-Server.aspx
Brad M. McGehee Microsoft SQL Server MVP Director of DBA Education, Red Gate Software www.bradmcgehee.com
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Am I the only one who noticed that the write latency for TEMPDB was measured in *seconds*, not ms?
I would think 3.5 sec is a lot more worrisome than 3.5ms. Just sayin'.
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Matt Guthrie (6/6/2011) Am I the only one who noticed that the write latency for TEMPDB was measured in *seconds*, not ms?
I would think 3.5 sec is a lot more worrisome than 3.5ms. Just sayin'.
You must be, as I missed this, and so did the technical reviewer. Good catch! Next time I will pay more attention to the scale, instead of making assumptions, which is apparently what I did when I looked at the graph.
This definitely needs more in-depth analysis to see what is really going on during this maintenance window within tempdb. I have already planned to do a specific follow-up article on tempdb, and I will add this to my list to investigate.
Brad M. McGehee Microsoft SQL Server MVP Director of DBA Education, Red Gate Software www.bradmcgehee.com
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