There could be some interaction.
If DBWR needs to write a block for
which the most recent changes are in
the log buffer but not in the log file, then
DBWR posts LGWR to write - and in
earlier versions of Oracle DBWR would
then wait for LGWR to sync, in later versions
DBWR links the buffer to a
Since when is redo log writing
performance handled by DB_WRITERS
or DBWR_IO_SLAVES?
Cheers
Nuno Souto
[EMAIL PROTECTED]
- Original Message -
Now, the Sr DBA here is screaming about the performance since I made the
change,
in particular, he says he's seeing high redo latch contention an
Did you try reducing _log_io_size to less than
one-third log_buffers size to make LGWR more active
and less busy .. We have had some success with it..
Thanks,
Ravi.
--- Thomas Jeff <[EMAIL PROTECTED]> wrote:
> Jonathan,
>
>
>
>
Jonathan,
WILLING IMMEDIATE
IMMEDIATE IMMEDIATE
NAME GETSMISSES TO WAIT %GETS
MISSES REQUEST %SLEEPS
=== === =
One interpretation of increased red latch contention
and log buffer space waits is that more work is being
done more quickly - so the log writer can't keep up.
This could mean:
a)the log writer has slowed down
b)the database writer(s) have speeded up, so there
is less
ning
> about.
>
> My idea of 'monitoring' was to assess free buffer waits, and to
> monitor
> the batch
> schedules to see if any degradation in timing had occurred, and since
> the change,
> neither has been an issue.
>
> Am I missing something?What stats sh
Title: DB_WRITER_PROCESSES vs DBWR_IO_SLAVES
Running 9.2.0.2 on AIX 4.3.3. We recently experienced a situation where
a datawarehouse database crashed due to a bug dealing with DBWR_IO_SLAVES > 0.
Oracle's recommended fix was to set the DBWR_IO_SLAVES to 0, which I did.