RE: Database writer

How many redo log space requests are you seeing and what is the size of the redo log buffer. Most tuning guidelines suggest increasing the size of the redo log buffer if you are seeing a lot of redo log space requests. In times of high activity you should see some space requests but it should stay near zero most of the time.

Buffers Scanned = "Number of times that the database writer scans the least-recently-used chain for more buffers to write. The scan can be invoked either by a "DBWR make free requests" or by a checkpoint. "

This is also probably not the best indication of problems with DBWR cleaning up dirty buffers fast enough which is what adding a DBWR would fix. There are a ton of DBWR stats in V$SYSSTAT that you can monitor that will tell you more if that is in fact a problem. Also there are related WAIT events you can look for. If you don't know about www.ixora.com.au, it is Steve Adams site and will give you lot of good scripts for interogating your system. You can also read his book http://safari.oreilly.com which is a very inexpensive way of reading lots of great books.

• Ethan Post

-----Original Message-----
Sent: Monday, June 04, 2001 1:37 PM
To: Multiple recipients of list ORACLE-L

by looking at the number of buffers scanned, redo log space requests and the lru scans. According to what I have read there was a possibility that my DBW0 was not performing very well. It was just a shot in the dark to try and squeeze some performance out of the db. Kev

-----Original Message-----
Sent: Monday, June 04, 2001 2:02 PM
To: Multiple recipients of list ORACLE-L

Kevin,

I apologize for asking but this is for the benefit of others possibly. But how did you determine that your instance may require an additional DBWR process. What led you to think that you had an bottleneck with only one process?

Thanks,
Ethan

-----Original Message-----
Sent: Monday, June 04, 2001 8:56 AM
To: Multiple recipients of list ORACLE-L

Hi all,

        I added db writer processes last week to try and improve performance of one
of my 8.1.7 db's on NT. Does anyone know if there is a way to see if Oracle actually started the additional db writer processes? I added db_writer_processes to the init file, the instance started so I am assuming that the db writer processes are working. But we all know what happens when we assume something. Any ideas would be appreciated.

Sincerely,
Kevin Kostyszyn
DBA
Dulcian, Inc
www.dulcian.com
kevin_at_dulcian.com

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