Thomas: I think you are right on monitoring the db writer performance. You should look the write complete waits/ free buffer waits to understand the db writer contention. I am not sure what prompted your Sr.DBA to think on increasing the IO slaves or db writers.
KG --- Thomas Jeff <[EMAIL PROTECTED]> wrote: > 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 understanding is that if AIO is enabled on the box, the rule > of > thumb > appears to be to use DB_WRITER_PROCESSES and set DBWR_IO_SLAVES = 0. > > 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 and > redo > log > buffer waits which he says validates his contention that we need to > get > back to > using DBWR_IO_SLAVES. > > I admit I'm confused. I don't clearly see the relationship that he > complaining > 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 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 and > 8i > and of > a more general nature. > > And yes, DISK_ASCYCH_IO is set to TRUE. > > Thanks. > > -------------------------------------------- > Jeffery D Thomas > DBA > Thomson Information Services > Thomson, Inc. > > Email: [EMAIL PROTECTED] > > Indy DBA Master Documentation available at: > http://gkmqp.tce.com/tis_dba > -------------------------------------------- > > > ===== Have a nice day !! ------------------------------------------------------------ Best Regards, K Gopalakrishnan, Bangalore, INDIA. -- Please see the official ORACLE-L FAQ: http://www.orafaq.net -- Author: K Gopalakrishnan INET: [EMAIL PROTECTED] Fat City Network Services -- 858-538-5051 http://www.fatcity.com San Diego, California -- Mailing list and web hosting services --------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: [EMAIL PROTECTED] (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB ORACLE-L (or the name of mailing list you want to be removed from). You may also send the HELP command for other information (like subscribing).
