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Thread: 1 Gig Redo Log file size ???

  1. #1
    Join Date
    Sep 2000
    Location
    Chicago, IL
    Posts
    316

    Question

    At busy insert time we have log switches (current redo log=250 MB) every 2-3 mins. To increase the log switches interval we were considering increasing the redo log size to 500MB or even 1 Gig.

    Does anyone know of any dis-advantages to that?
    Does anyone have redo logs this big?
    Any other suggestions to increase redo log switch interval?

  2. #2
    Join Date
    Nov 2000
    Location
    greenwich.ct.us
    Posts
    9,092
    That's a pretty big redo log already. You have to weigh the time you are doing a log switch with the amount of data that you will potentially lose if the log file goes away...
    Jeff Hunter

  3. #3
    Join Date
    Dec 2000
    Location
    Ljubljana, Slovenia
    Posts
    4,439
    2-3 minutes for a peak-hours doesn't seem to frequent to me. What's the log-switch interval during normal load? Do you have any complaints about "checkpoint not complete" or "archiving not be fast enough" in your alert log?

    If you realy want to set a redo log so big (500M or 1G) I'd advise you to perform a couple of explicit checkpoints during filling of your online log (set LOG_CHECKPOINT_INTERVAL and/or LOG_CHECKPOINT_TIMEOUT properly). If you do not do so you'll potentially face two problems:

    1. In case you loose all members of your active logfile group you'll loose quite a big amount of data (1G worth of transactions).
    2. In case your database crashes or your performs shutdown abort your instance recovery after restart might take quite a long time.

    Jurij Modic
    ASCII a stupid question, get a stupid ANSI
    24 hours in a day .... 24 beer in a case .... coincidence?

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