Re: Help me tuning this wait event:log file sync

From: Howard J. Rogers <howardjr2000_at_yahoo.com.au>
Date: Thu, 18 Jul 2002 06:09:08 +1000
Message-ID: <ah4is1$7sr$1@lust.ihug.co.nz>

"Yong Huang" <yong321_at_yahoo.com> wrote in message news:31c7ecb9ecd7247035a7645474990fd7.99975_at_mygate.mailgate.org...
> Hi, Howard,
>
> Writing log entries is parallelized (wait event: log file parallel
> write). Only log file headers are written sequentially. This means that
> the same log entries are written to all members of a log group. If the
> written data is wrong, it's wrong in all members. Think carefully when
> you say "LGWR makes an error".

I do so wish that people would stop telling me to "think carefully" as if I don't.

>It can mean Oracle's error or the error
> of anything underneath (OS, RAID hardware). The underlined OS or
> hardware only replicates Oracle's error. Are you saying LGWR can write
> correct logs to one member but corrupt logs to another?

Yes, that's exactly what I'm saying.

HJR
>
> Yong Huang
>
> you wrote:
>
> waiting to happen if that's all you've got. LGWR makes an error writing
> to
> your one member -and the hardware immediately replicates that corruption
> onto your mirror(s). You've now got two identical copies of useless redo
>
>
> --
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Received on Wed Jul 17 2002 - 15:09:08 CDT