RE: Log file synch / direct path writes

The log buffer is one meg right now. The application uses many, very small transactions. There is no possibility of combining the statements into a larger single transaction. There are no waits to allocate log buffer space. I have also considered setting the _log_io_size to less than 1/3 a meg instead of reducing the size of the buffer. The next thing I am going to try is to find out if there is a LGWR background write event. This would let me know if the buffer is ever filling to the point of background writes.

Thanks for the responses.
Erik

> -----Original Message-----
> From: Jared Still [SMTP:jkstill_at_cybcon.com]
> Sent: Saturday, June 22, 2002 1:30 PM
> To: ORACLE-L_at_fatcity.com; Erik Williams
> Subject: Re: Log file synch / direct path writes
>
>
> Just how large is your overly large log buffer?
>
> 10 meg?
>
> 100 meg?
>
> 1 Gig??? ( ok, I've never heard of one this big,
> but you never know ;)
>
> Jared
>
> On Friday 21 June 2002 12:48, Erik Williams wrote:
> > I have an instance that is waiting on log file synchs. I suspect that
> the
> > waits are a result of a overly large redo log buffer. There are also
> > considerable waits on direct path writes. The redo logs are on QuickIO,
> so
> > I assume that the writes LGWR is writing asynchronously and not a source
> of
> > the log file synchs. I want to be sure that the log file synchs and
> direct
> > path writes are not related before I begin to experiment with the size
> of
> > the redo log buffer. How can I be sure that the waits are being caused
> by
> > DBWR and not LGWR? What are possible fixes for the direct path writes if
> it
> > is the DBWR causing them? Multiple DBWR? The datafiles are not on
> QuickIO,
> > just the redo.
> >
> > Thanks
> > Erik

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Author: Erik Williams
  INET: ewilliams_at_brownco.com

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