Re: Tuning DBWR

That's not the response I was expecting, but it may be a clue. Are there some fairly large sorting processes going on fairly regularly ? Heavy I/O at this rate suggests that you may be doing a lot of sorting through the db_block_buffers.

Check v$sysstat for 'sort (disks)' and 'sorts (rows)'

Check your sort_area_size, sort_area_retained_size If the values are around 32K/64K (the defaults are something like this) make them bigger - up to 256K would be perfectly reasonable for a first estimate.

Then check that you have 'sort_direct_writes=true'.

--

Jonathan Lewis
Yet another Oracle-related web site: http://www.jlcomp.demon.co.uk

sandrazil_at_my-deja.com wrote in message <85vd3t$cqa$1_at_nnrp1.deja.com>...
>Thanks for the suggestion. We determined I/O bottleneck by running
>glance. Whenever there is a logswitch/checkpoint glance alerts for I/O
>bottleneck. I did check the alertlog for messages but there was none.
> Changing the db_block_max_dirty_target setting from 50% to 1%
>resulted in 100% I/O utilization for 30-50 secs every 3-5 minutes,
>instead of a I/O bottleneck of 2-3 mts every logswitch. During these
>period we have a very poor response time.
>
Received on Mon Jan 17 2000 - 12:45:53 CST