What is the purpose of configuring more than one Database Writer Processes and How many should be used?

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- DBWn process records modified buffers in Database Buffer Cache to data files so that user process can always find free buffers.

- To efficiently release the buffer cache to make it available to user processes, you can use multiple DBWn processes.

- We can configure new processes (DBW1 through DBW9 and DBWa through DBWj) to improve write performance if our system modifies data heavily.

- The initialization parameter DB_WRITER_PROCESSES specifies the number of DBWn processes up to a maximum number of 20.

- If the Unix system being used is fitted of asynchronous input/output processing, then only one DBWn process is enough if not the case the whole DBWn processes required will be twice the number of disks used by oracle, and this can be set with DB_WRITER_PROCESSES initialization parameter.

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