Re: What are the implications of having several instances on a server sharing

From: tim@xxxxxxxxxxxxx
To: oracle-l@xxxxxxxxxxxxx
Date: Wed, 29 Sep 2004 12:41:53 -0600 (MDT)
Ana,
Especially if you are using the OFA standard (almost unavoidable these days, 
thank goodness!), then you won't have any performance or contention problems 
having multiple database instances sharing the same ORACLE_HOME.  The OFA 
(a.k.a. "Optimal Flexible Architecture") standard provides, among other 
benefits, separation of the Oracle software distribution (i.e. ORACLE_HOME 
directory tree) from database files and config/trace/log/administrative files.

In the past, there were problems with some limits impose by the various 
distributed file-systems (i.e. Novell shared drives, etc) on some OS's (i.e. 
NT4.0 and prior, etc) causes failures due to file locks, but I haven't heard 
anything about that lately.  Again, those were straight-out failures, not 
performance issues, anyway...

The pro's and con's of sharing ORACLE_HOME are:

    Pro1=saves space
    Pro2=one-stop patching (i.e. "all for one and one for all")

    Con1=one-stop patching (i.e. "all for one and one for all")
       1a) Oracle patching/maintenance applies to all databases, may not be 
desirable
    Con2=same OS user owns all processes
       2a) more difficult to monitor each instance from OS level
       2b) impossible to separate "ownership" of databases to different DBA 
teams

Some of the "cons" may or may not apply to your situation...

Hope this helps...

-Tim



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Subject: What are the implications of having several instances on a server 
sharing
 the oracle home?
To: oracle-l@xxxxxxxxxxxxx
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From: Ana Choto <achoto@xxxxxxxxxxxx>
Date: Wed, 29 Sep 2004 14:13:20 -0400
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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 8.1.7.4, 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
settings?

Thanks

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

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Re: What are the implications of having several instances on a server sharing

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