Issue with High wait stats

  • Hi All,

    I have a SQL Server 2012 SP2 instance running on Server 2012 R2, Its virtualized and has 4 processors and 32Gb of RAM, SQL Server max memory is 28Gb. Always On Availability Groups is being used with two nodes, primary and secondary.

    I am seeing high wait stats.

    On the primary node, the two highest are in the lead by a country mile, they are:

    PREEMPTIVE_HADR_LEASE_MECHANISM 50.77 wait percentage

    and

    PREEMPTIVE_SP_SERVER_DIAGNOSTICS 24.04 wait percentage

    On the secondary it is:

    REDO_THREAD_PENDING_WORK 82.38 wait percentage

    and following a long way behind is:

    CXPACKET 7.90 wait percentage.

    I am after ideas for tracking down what these are and what to do about it.

    Ta

    David

    ============================================================
    David

    http://www.sqlservercentral.com/articles/Best+Practices/61537/[/url]

  • dbalmf (1/7/2015)


    Hi All,

    I have a SQL Server 2012 SP2 instance running on Server 2012 R2, Its virtualized and has 4 processors and 32Gb of RAM, SQL Server max memory is 28Gb. Always On Availability Groups is being used with two nodes, primary and secondary.

    I am seeing high wait stats.

    On the primary node, the two highest are in the lead by a country mile, they are:

    PREEMPTIVE_HADR_LEASE_MECHANISM 50.77 wait percentage

    and

    PREEMPTIVE_SP_SERVER_DIAGNOSTICS 24.04 wait percentage

    On the secondary it is:

    REDO_THREAD_PENDING_WORK 82.38 wait percentage

    and following a long way behind is:

    CXPACKET 7.90 wait percentage.

    I am after ideas for tracking down what these are and what to do about it.

    Ta

    David

    Both of those are behind the scenes and should probably be pretty high. Server_diagnostics is one that runs constantly to trap info about server health and the HADR is to be used by CSS for diagnostics.

    Like the noise waits from prior versions of SQL, you can add these to that list.

    The redo_thread would be expected with the presence of AlwaysOn.

    Jason...AKA CirqueDeSQLeil
    _______________________________________________
    I have given a name to my pain...MCM SQL Server, MVP
    SQL RNNR
    Posting Performance Based Questions - Gail Shaw[/url]
    Learn Extended Events

  • Hi Jason,

    thanks for that, I'll add them to the exclusions list in the query.

    Ta

    David

    ============================================================
    David

    http://www.sqlservercentral.com/articles/Best+Practices/61537/[/url]

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