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
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
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.
Now, my
in timing had occurred, and since
the change,
neither has been an issue.
Am I missing something?What stats should I be assessing to
contrast
the
use of DB_WRITER_PROCESSES vs DBWR_IO_SLAVES? And yes, I've googled
and
metalinked and and most information is mainly pertinent to 7.3.4
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
Jonathan,
WILLING IMMEDIATE
IMMEDIATE IMMEDIATE
NAME GETSMISSES TO WAIT %GETS
MISSES REQUEST %SLEEPS
=== === =
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,
