Re: Redo Question

From: hpuxrac <>
Date: Fri, 28 Mar 2008 17:16:24 -0700 (PDT)
Message-ID: <>

On Mar 28, 10:27 am, wrote:
> Hi,
> We are trying to see what the optimal size of our redo logs should be
> and how many we should have.
> We are running 10g, and we know that there is the MTTR_ parameter.
> But for now, we want to the the log_checkpoint......
> We have a high transaction system.  Currently we have 5 redo logs,
> each 50M.  We are still receiving the error "Check point not
> complete".
> I'm not sure if creating more groups is the answer, shrinking the log
> size, or making the logs bigger.  We are researching it, but in the
> meantime this error is happening frequently.
> We are looking for some advice on what to do given the path we want to
> take......
> Thanks for any help.
> John.

Are you seeing waits for log buffer space or for log file sync?

If you see "enough" waits for log buffer space you want to think about making your memory based log buffer larger.

Log file sync you want to look at performance of IO to the online log buffers.

Everything being equal and keeping in mind there are "no silver bullets" for most modern systems there isn't a real benefit to making online logs small. 500 meg up to several gig in size might make sense for your environment. You can always force a log switch as desired. Received on Fri Mar 28 2008 - 19:16:24 CDT

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