Re: Write Complete Waits

Steve,

What is the effect of reducing db_files and db_file_simultaneous_writes , presumably these are used in an internal algorithm as part of a calculation of some sort ?

Regards

Neil

Steve Adams wrote in message <384eec92.38295185_at_news.eagles.bbs.net.au>...
>Hi Roy,
>
>In general, 'write complete waits' indicate either that the internal
>write batch size is too large, or that you are checkpointing hot
>blocks too intensively, rather than that write I/O is too slow. With
>only three physical disks, you should set db_files as low as possible
>and set db_file_simultaneous_writes to 1. Then set
>db_block_checkpoint_batch to db_files/4.
>
>If you are using incremental checkpoints (db_block_max_dirty_target),
>don't be too ambitious. Otherwise make sure that background
>checkpoints are not too frequent.
>
>Hope this helps,
>Regards,
>Steve Adams
>http://www.ixora.com.au/
>http://www.oreilly.com/catalog/orinternals/
>http://www.christianity.com.au/
>
>
>On Wed, 08 Dec 1999 21:51:39 GMT, rspeaker_at_my-deja.com wrote:
>
>>I currently have an Oracle 8.0.4 system running on an RS/6000 with 4x332
>>mhz CPU and 1 GB RAM. I have async I/O configured on the system. The
>>application in question has its 'data' file striped across 2 disks, and
>>the corresponding 'index' file on 1 disk. I have been seeing as much as
>>10% write complete waits throughout the day (according to the monitoring
>>tool I am using). I understand the fix for this to be either enabling
>>Async I/O or starting multiple db writers with the dbwr_io_slave
>>parameter. I have async I/O enabled but still see the waits. Will it
>>help/hurt performance to add a second db writer as well? Any other
>>suggestions?
>>
>>thanks,
>>Roy
>>
>>
>>Sent via Deja.com http://www.deja.com/
>>Before you buy.
>
Received on Thu Dec 09 1999 - 08:36:19 CST