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Thread: Log Buffer Size

  1. #21
    Join Date
    Jun 2006
    Quote Originally Posted by KenEwald
    I'm not sure I explained my question properly, let me try it this way.

    Let's compare two systems that generate 3gb/hr.

    One has 3 - 100mb redo logs and the other has 3 - 1gb redo logs.

    If the transactions were evenly distriubted over time, the first system would generate a log file every 2 minutes. The other every 20 minutes.

    What's the rationale for sand-bagging I/O? Would it be better to more evenly distribute it over time?

    Just curious,

    Huh? Define Sand-bagging i/o?
    It all depends on how the system is layed out...
    Sure I/O will be terrible if you share drives between the arch file systems and redo logs (raw, file system).... But If you don't and have dedicated devices for each, then what does it matter if occasionally I/O spikes for 10 seconds to generate an arch log?

    It better to generate fewer archive logs to reduce checkpoints, but in the end this must be ballanced by many other factors(ie data guard, backups etc).

    I guess all i'm saying is a 2M log file is generally a bad idea, no matter what the system. It might be ok for say a read only or a DW where all loads are direct path and very little redo is generated.

    Hope this helps,
    Last edited by ixion; 10-16-2006 at 02:32 PM.

  2. #22
    Join Date
    Jan 2013
    Hi all,
    good advices, I was wondering if there is a way to see how much memory the redo buffer is consuming..I know we have the size , but how much of that size is used in a specific moment ???


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