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 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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