Re: DBWR slave process

Version?

If it's anything other than 7 or 8.0, you don't want to be messing with DBWR slaves, since they only parallelize the writing of buffers to disk. Instead, use the multiple DBWR processes feature, since they parallelize both on the buffer collection *and* the buffer writes. The two methods are incompatible with each other.

DBWR slaves are configured using the DBWR_IO_SLAVES init.ora parameter. Multiple DBWR processes are configured using the DB_WRITER_PROCESSES init.ora parameter.

As to why: because multiple processes (including slaves) mean that one process can be writing to data file 3 whilst another is simultaneously writing to data file 6. That means the writes are over quicker; checkpoints complete faster; I/O contention (between DBWR writing and your server process reading) is minimised. It's a thoroughly good thing, imho, where there are indications from statistics that DBWR I/O behaviour may be compromising performance.

8i permitted up to 10 ARCH processes. They get spawned automatically as the server detects the need for them, but you can spawn several at Instance startup by setting the LOG_ARCHIVE_MAX_PROCESSES init.ora parameter. That can be dynamically altered with an alter system command to manually cause the creation of additional processes, too.

Regards
HJR "Gaurang Patel" <gvpatel_at_hotmail.com> wrote in message news:14133c52.0206171628.56cf7d83_at_posting.google.com...
> Can anyone explain me about DBWR slave process?
>
> Since we have DBWR process what is the need of DBWR SLAVE process?
>
> I heard something like async i/o and DBWR SLAVE help to achivw that.
>
> How?
>
> Is there any other SLAVE process for other oracle processes
> like(LGWR,CKPT,ARCH ..etc)?
>
> Thanks
Received on Mon Jun 17 2002 - 21:47:38 CDT