THRESHOLD VALUE FOR DIRTY BUFFERS
303567Jun 28 2003 — edited Jun 29 2003Hi everybody.
It seems that database writer process(DBWn) writes the dirty buffers to the disk when:
1. The server process needs to make room in the buffer cache to read more data in for user processes.
2. DBW0 is told to write data to disk by the LOGWR process. (which is called a checkpoint)
3. Every three seconds due to a timeout.
4. The number of dirty buffers reach a threshold value.
I have 3 questions based on what is said above:
1. Is it that LOGWR talks only to DBW0 at checkpoint time, even though recent versions of Oracle accomodate upto a maximum of 10 DBWs?
2. How do we specify the threshold value that case 4 talks about? Do we set it in init.ora parameter file and can we change it dynamically?
Is 3 seconds not too short a time to keep on doing a database write operation?
Thanks,
Kishore.