SQLServerCentral Best Practices Clinic: Part 4

  • Brad McGehee

    SSCertifiable

    Points: 5272

    Comments posted to this topic are about the item SQLServerCentral Best Practices Clinic: Part 4

    Brad M. McGehee
    DBA

  • currym

    SSC Eights!

    Points: 919

    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

  • Brad McGehee

    SSCertifiable

    Points: 5272

    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
    DBA

  • currym

    SSC Eights!

    Points: 919

    Great, thanks!

    Patrick

  • Matt Guthrie

    SSC Enthusiast

    Points: 161

    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'.

  • Brad McGehee

    SSCertifiable

    Points: 5272

    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
    DBA

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