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  1. #1
    Join Date
    Sep 2002

    Unanswered: Checkpoint duration


    I see that the checkpoint duration in the online.log file is about 15 seconds and it varies from 14-16 seconds.Is this a high water mark or 15 seconds is acceptable?Does this duration of checkpoint cause a serious locking problem from requests coming in .Would this lead to any sort of problem.

    If 15 seconds is not acceptable do we have to change the parameters in the onconfig file to reduce the checkpoint time.

    I am new to informix.Pls advice.


  2. #2
    Join Date
    Aug 2002
    During a checkpoint all writing transactions
    will be blocked.

    So especially for OLTP environments the goal is to
    keep the checkpoint duration short.
    HighEnd OLTP system normally have 3 seconds
    max. checkpoint duration.

    You might consider lowering your LRU_MIN_DIRTY/LRU_MAX_DIRTY
    parameters to achieve this goal.
    Values of 1/2 or 5/10 for these parameters are quite normal.

    There are also other factors which influence the frequency of
    checkpoints like the CKPTINTVL onconfig-parameter and the
    size of the physical log (if it is 75% full, a checkpoint is
    automatically initiated).

    If you are running on IFMX 9.2x, you have so called "fuzzy checkpoints". During a fuzzy checkpoint not all dirty pages
    are written from the buffer cache to disk, thus resulting in
    shorter checkpoint durations.
    This feature is not available in IFMX 7.x.

    Also the number of buffers, the I/O throughput, kaio etc.
    could influence checkpoint durations.
    If you really want the best, you might consider ordering
    an IFMX consultant to tune your environment.


    Best regards

    IT-Consulting Herber

    Download the IFMX Database-Monitor for free at:

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