RE: What are the implications of having several instances on a se rver sharing the oracle home?

  • From: "Stevens, Ed" <ED.STEVENS@xxxxxxxxxxxxxxxxxx>
  • To: oracle-l@xxxxxxxxxxxxx
  • Date: Wed, 29 Sep 2004 13:43:21 -0500

To be blunt, your boss is clueless. What kind of contention is he
visualizing here?

On some of our test systems, running Windows (which some would say is
madness itself) we are running over a dozen separate databases (which many
would say is madness itself) with one Oracle home.  A couple of our prod
servers, running Windows, are supporting up to 6 separate databases from a
single home.  While many would claim our setup is insane, it would be for
reasons other than running multiple db's from a single Oracle Home.

How many things run on the same computer using the same binaries from the
OS?  Is that considered contention?  Let's install a separate OS for each
app. If you have 3 separate Word documents open at once, would you want them
to each be driven by separate installations of Word? Let's install Word into
a separate directory for each document.

Ask your boss to explain exactly what kind of contention (disk? memory?
cpu?) he is concerned about, and then ask him to explain the theory behind
releaving that contention by using multiple Oracle Homes. Gently point up
the fallacies as they surface -- as they most certainly will.  With  careful
questioning and a bit of explanation, you might get him to talk himself into
a better understanding.  

Ed Stevens 

-----Original Message-----
From: Ana Choto [mailto:achoto@xxxxxxxxxxxx]
Sent: Wednesday, September 29, 2004 1:13 PM
To: oracle-l@xxxxxxxxxxxxx
Subject: What are the implications of having several instances on a
server sharing the oracle home?

My boss thinks that this could cause problems.  I say it's OK to have, say
three Oracle instances  (or more) sharing the binaries, as long as we have
enough memory and space.  He thinks we should install the software for each
instance to alleviate contention for the binaries.  Space is not an issue
for him.  The problem with this setting is that I will have to apply
patches to all of them.

I have on a server four databases, three of them share the binaries, they
are on 9iR2, and I also have a 10G instance on its own oracle home.  The 9i
DBs are not heavily used so I can't tell if there is performance issues
with them.  I don't see a problem with the 10G db, although no one but me
is using it.

On another server I have three databases in their own oracle home.  Two
instances run on, one is the datawarehouse and the other one is
oltp.  No performance problems there.  Another oltp database (9iR2) resides
on the server, and I don't see any performance issues there either.

Is someone out there willing to share his/her experiences with any of these


Ana E. Choto
American University
e-Operations - Information Technology
Phone (202) 885-2275
Fax      (202) 885-2224


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