RE: Multiple Instance in Unix

From: Bobak, Mark <>
Date: Fri, 7 Aug 2009 07:57:02 -0400
Message-ID: <>

Yes, exactly. But also, keep in mind, if, for example, you have an /etc/oratab that looks like this: db1:/oracle/product/10.2.0:Y

Then, you can do:
. oraenv

and enter 'db1' or 'db2' to switch ORACLE_HOME and ORACLE_SID to appropriate values for the instance you want to work on. Then, if you do:
sqlplus / as sysdba

You'll be connected as SYS to whatever instance is running w/ that ORACLE_HOME and ORACLE_SID.

But, keep in mind, once both instances are up and running, if you just want to connect to one or the other as a non-SYS user, you don't need to keep running '. oraenv'. You can just do 'sqlplus yourusername_at_db1' or 'sqlplus yourusername_at_db2' to get to whichever instance you need. (Assuming of course a proper listener.ora and tnsnames.ora setup.)

Hope that helps,


From: Amir Gheibi [] Sent: Friday, August 07, 2009 4:44
To: Bobak, Mark
Subject: Re: Multiple Instance in Unix

Hi Mark,

Thanks for the swift reply. Appreciate it.

But if re-set ORACLE_SID to the new SID and keep the ORACLE_HOME, how would I access to the first instance? Change ORACLE_SID back to the old SID whenever is needed?

~ Amir

On Fri, Aug 7, 2009 at 4:25 PM, Bobak, Mark <<>> wrote: Hi Amir,

This is a common practice. There is no need to create a new OS user. You can even create a new database under the same Oracle home.

The thing to keep in mind is that the combination of ORACLE_SID and ORACLE_HOME need to be unique. So, that will uniquely identify an instance on a host, and then that instance's pfile/spfile will point to your database's control file(s). In that way, your new instance will clearly identify which database it will mount and open.

Hope that helps,


From:<> [<>] On Behalf Of Amir Gheibi [<>] Sent: Friday, August 07, 2009 4:18
Subject: Multiple Instance in Unix

Hi listers,

I have a HP Unix box that has Oracle 10g R2 installed on it. There is already an instance running and a database attached to it. I need to create another instance and database. There is no X Server installed on the OS. I created the first database through command line.

My question is whether I have to create another OS user in order to create the new instance? Or I can use the same OS user (oracle:dba) to create the new instance? As I need to set environment variables then if I use the same OS user, what would happen to the first instance?

Is there a guideline on how to do this?


~ Amir Gheibi

-- Received on Fri Aug 07 2009 - 06:57:02 CDT

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