Re: Can OFA and multiple instances lead to DBWR contention

Seems that you have a problem with my title of "Senior Oracle DBA". You reference it twice in your reply.

You did make my point though. The blanket statement that multiple Instances is a bad idea is just wrong. All databases are different, so you can not just make blanket statements that a particular setup is right or wrong for everybody. Each DBA has to be able to properly evaluate his/her own needs.

As for the eggs and baskets, everything on our servers have backups. We have multiple power supplies. Not saying that something could not happen that causes complete failure, but we try. We have well over 100 Oracle instanaces and there is no way to justify having one instance per machine.

John Jones
Senior Oracle DBA
Duke University, OIT
john.jones_at_duke.edu
"Howard J. Rogers" <howardjr_at_www.com> wrote in message news:3b5d3fdc_at_usenet.per.paradox.net.au...
> In a perfect, budget-free world, yes. Because *any* activity on
> Instance/Database A is likely to compete with any activity on
> Instance/Database B for server resources.
>
> Whether the competition is serious enough to warrant the added expense and
> maintenance effort involved is up to you, the Senior Oracle DBA, to
 evaluate
> and work out.
>
> There is also the question of eggs and baskets: if your server power
 supply
> dies, you have multiple Instances taken out at the same time. Distribute
> them around multiple boxes, and you might lose 1, but not the lot. Is
 that
> an issue? That's what Senior DBAs are there to work out for their own
> particular environments.
>
> Regards
> HJR
>
> "John Jones" <john.jones_at_duke.edu> wrote in message
> news:9j99jg$3ks$1_at_news.duke.edu...
> > Please expand on that thought. Why would numerous SIDs be a VERY BAD
> > IDEA.???
> > We have IBM's M80 servers. They have multiple processors, 8 Gig of RAM,
 and
> > configured on Shark disk. One instance on this server would have little
 to
> > no load on it. On some of our smaller servers we have multiple
 instances
> > because they are either small or have very little activity. Are you
 saying
> > each of these should also be on seperate servers????
> >
> > --
> > John Jones
> > Senior Oracle DBA
> > Duke University, OIT
> > john.jones_at_duke.edu
> > "Sybrand Bakker" <postbus_at_sybrandb.demon.nl> wrote in message
> > news:tle4mtt4qgl619_at_beta-news.demon.nl...
> > >
> > > "Akinwande Seigmund Walter-Johnson III" <asjohns_at_midway.uchicago.edu>
 wrote
> > > in message news:8dE57.65$_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 Tue Jul 24 2001 - 09:44:33 CDT