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100% Buffer Cache hit + High Memory Paging

  • March 1, 2011 at 8:16 am

    #232767

    I think the buffer cache hit should always be close to 100% correct?

    What does it mean when the memory paging is high but the cache hit is 100%

    Thanks

  • March 1, 2011 at 9:38 am

    #1293039

    Yep. Target cache hit ratio should be about 99% in most cases.

    Your high cache hit shows that the ram allocated to SQL server is working great, however the high paging indicates that there is probably not enough ram allocated to the OS. You may want to leave at least 2G for the OS, and even more if the system is not dedicated to only SQL server (like if it acts as a web server too, or a file server).

    Course, if doing this drops your cache hit ratio or shortens your page life expectancy to much, then you may need to add more ram if your version of SQL server can utilize it.

    Always test these sorts of changes before rolling them into production.

    Jim

    Jim Murphy
    http://www.sqlwatchmen.com
    @SQLMurph

  • March 1, 2011 at 9:42 am

    #1293044

    Thanks I was trouble shooting this morning. Seems like a third party backup software someone installed was causing the high memory pages. We disabled it and everything is back to normal now.

  • October 14, 2011 at 6:52 am

    #1394615

    This reply helped.

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