Re: Write Complete Waits

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 Wed Dec 08 1999 - 17:46:05 CST