Re: Can OFA and multiple instances lead to DBWR contention

That's not the suggestion you should give him.

OFA is usually followed only when you consider administration files, such as init.ora, listener.ora / tnsnames.ora, oratab... Datafiles, logfiles, controlfiles should all be spread out unless you have underlined hardware striping. So in a sense strict OFA is broken to get better performance and less chance of losing those critical files.

Even when you have hardware striping, it's not good to create datafiles all in one logical group / unit (LUN). That is, you may think it's OK to create all datafiles under the mount point /db1/oradata because you're using RAID0, 1+0 or 5. But you may get better performance to spread them onto /db1/oradata and /db2/oradata if the second mount point is on a different LUN. If you use Veritas volume manager, check it out by vxprint -htf. This just adds one more layer of consideration of I/O balance to what you learned a few years ago.

Yong Huang
yong321_at_yahoo.com

"Sybrand Bakker" <postbus_at_sybrandb.demon.nl> wrote in message news:<tle4mtt4qgl619_at_beta-news.demon.nl>...
> "Akinwande Seigmund Walter-Johnson III" <asjohns_at_midway.uchicago.edu> wrote
> in message news:8dE57.65$_4.4568_at_news.uchicago.edu...
> > All,
> > Running multiple instances on one machine and using OFA requires that all
> > data for all instances be written to
> > one or more disk's dedicated for data.
> > Couldn't contention arise between all DBWR's for the numerous SID's ?
> >
> >
> >
>
> Numerous SIDs on one server are a VERY BAD IDEA anyway, OFA or no OFA.
>
> Regards,
>
> Sybrand Bakker, Senior Oracle DBA
Received on Thu Jul 19 2001 - 17:54:45 CDT