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Buffer Cache hit ratio

  • August 27, 2014 at 1:58 pm

    #397266

    Hi,

    We are checking the Buffer cache hit ratio (as % using Buffer cache hit ratio / Buffer cache hit ratio base) sampling every 15 sec. This is nearly always 100% but there are occasional (1 in 10) values which give results way off the normal. The counter and base values have spikes resulting in percentages (eg 5% or 150%) which throw off our trend reporting. We would like to know what the actual base and raw counter values represent (eg. a count of the number of requests for pages in the buffer pool?) and why the base would intermittently differ so erratically from the raw count?

    Thanks

    Matthew

    MattF

  • August 27, 2014 at 2:27 pm

    #1741489

    Rather ignore that counter. It's useless. Even on a server that's under severe memory pressure it'll be sitting near 100%

    Gail Shaw
    Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
    SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability

    We walk in the dark places no others will enter
    We stand on the bridge and no one may pass

  • September 9, 2014 at 12:28 pm

    #1744219

    Hello,

    Gila already hit the direction you should take: useless metric and not what you are looking for.

    To better explain the reasons why that metric isn't getting you what you think it is please review this awesome post: https://www.simple-talk.com/sql/database-administration/great-sql-server-debates-buffer-cache-hit-ratio/

    I spent some time a few weeks ago on this very same task to look up this setting as well. Utilizing information on this post I was able to see actual Buffer Cache Hit Ratio values.

    Hope that helps and good luck!

    Regards,

    Jeremy

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