Re: DBWR flush parameter

From: Steve Adams <steve.adams_at_ixora.com.au>
Date: Tue, 07 Dec 1999 12:15:36 GMT
Message-ID: <384ce996.287271264@news.eagles.bbs.net.au>

Hello Andre,

You may be thinking of _db_block_max_scan_cnt which defaults to

floor(0.25 * db_block_buffers / db_block_lru_latches) However, the buffers inspected need not be dirty. They are more likely to be pinned. There is another threshold set by _db_large_dirty_queue that would trigger a make free request to DBWn long before the default max scan count could be reached, if a large number of dirty buffers were inspected during an LRU scan. This parameter defaults to 1/16 of the internal write batch size (see documentation) rounded to the nearest buffer.

Note that the above applies up to Oracle 8.0 only. The DBWn algorithm and parameters have changed dramatically in 8.1.

Regards,
Steve Adams

http://www.ixora.com.au/

http://www.oreilly.com/catalog/orinternals/

http://www.christianity.com.au/

On Mon, 6 Dec 1999 00:05:27 -0200, "Andre Whittick Nasser" <awnasser_at_openlink.com.br> wrote:

>I need to know what parameter sets the number of dirty buffers that the
>server process searches in the LRU list before it forces a flush by DBWR.
Received on Tue Dec 07 1999 - 06:15:36 CST