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Buffer Cache Hit Ratio is Zero and PLE is High

  • August 6, 2012 at 3:35 pm

    #262426

    We have a procedure that executes every 10 minutes on our instances that inserts the contents of sys.dm_os_performance_counters into a table. This weekend, we received alerts that Buffer Cache Hit Ratio dropped to zero on one of our instances. Looking at the contents of the performance counter table for the time range in question, I see the following result set:

    I cannot figure out how Buffer Cache Hit Ratio can be zero and Page Life Expectancy can continue to increase. Any insight would be appreciated.

    Thanks,

    Frank Gill

    http://skreebydba.com/

  • August 6, 2012 at 3:42 pm

    #1522317

    Were you having network issues or similar problems at the time? You won't get a cache hit rate if there's no activity as far as I remember, but page life would continue to increase due to the complete lack of pressure. I don't use cache hit rate as much as a few other counters, as it's misleading and doesn't always trigger under significant pressure.

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  • August 6, 2012 at 3:53 pm

    #1522325

    Craig,

    Thanks for the response. I will investigate if there were any network issues. I know about the issues with Buffer Cache Hit Ratio and am working to get it removed and replaced with Physical Reads/Sec. Unfortunately, we still have an alert set up for it.

    Thanks again,

    Frank

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