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  1. #1
    Join Date
    Jan 2004

    Unanswered: buffer stats down after fast cache hardware installed?

    Good morning. I installed write cahching hardware on my disk subsystems over the weekend and I was surprized to find my buffer stats down from what they normall are:

    dskreads pagreads bufreads %cached dskwrits pagwrits bufwrits %cached
    35454219 112790800 2665919344 98.67 6032509 11332052 59579389 89.87

    My reads usually run at 99.xx% and writes hover between 97-98.xx% Does this make sense to anyone?

  2. #2
    Join Date
    Jan 2003

    Lightbulb LRU Background writes faster


    Because of your writes being faster ( because the writes go to disk cache instead of directly to disk ) the background writes caused by exceeding the LRU_MAX_DIRTY threshold will also be faster. Therefore buffers can be liberated in memory faster. This then can have the effect buffers have to be read from disk again when they have to be modified, resulting in a worse write-cache ratio.

    Make sure you reinitialize the figures ( onstat -z) periodically to be able to compare them .

    Best regards

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