Re: LOG_BUFFER tuning

Charles J. Fisher <cfisher_at_rhadmin.org> wrote:
>In a paper on dbatoolbox.com, Susan Georgson says that the following SQL
>call should always return zero, and to increase LOG_BUFFER if it isn't
>zero:
>
>SELECT name, value FROM v$sysstat WHERE name='redo buffer allocation retries';
>
>On an Oracle 7 server suffering performance problems, I've increased
>LOG_BUFFER to the point that I'm getting approx. 30 of these retries a
>day.
>
>Is this close enough, or does the value need to be ABSOLUTELY zero?

Probably not significant any more.

Run a utlbstat/utlestat report and see if, "redo buffer allocation retries" are a significant proportion of the total wait. Ask yourself how much faster the database would be if they never happened. You'll probably find that the answer is "not very", and you can get to work on the top wait events instead.

-- 
Andrew Mobbs - http://www.chiark.greenend.org.uk/~andrewm/