Re: What's the difference between DBWR_IO_SLAVES and DB_WRITER_PROCESSES?

I believe that IO slaves exist to emulate async I/O and do nothing more that write block supplied by a db_writer.

DB_WRITER 'collect' blocks from the SGA that need to be written.

Consequently you could have a 'collection bottleneck' in your system by having only one db_writer (other processes may see excessive blocks pinned waiting for writes) even when you have multiple I/O slaves.

--

Jonathan Lewis
Yet another Oracle-related web site: www.jlcomp.demon.co.uk

Olivier Barry wrote in message <376FB4B0.961D5AFD_at_grenoble.hp.com>...
>Hi all,
>
>I found 2 different parameters (Oracle 8) to optimize the writing
>performances: DBWR_IO_SLAVES and DB_WRITER_PROCESSES.
>
>I understand that the first one configures the number of 'slaves' of the
>DB writer (what is a slave?) and the second one configures the number of
>DB writer processes.
>
>What's the difference between them and when should I use one rather the
>other?
Received on Tue Jun 22 1999 - 11:50:57 CDT