One good reason for separate sets of binaries is patching and patch testing on one database without affecting others. Having all installations under different Unix users (and also groups in this case!) may be better for security but will make the everyday maintenance, refreshes etc probably harder... as you'll have various problems with permissioning and file access, need to constantly su between users, chmod/chown files etc... that's unless you want to chmod 777 all your directories & files, which would heavily go against the security principles again. I know quite many shops which use a separate software installation (and set of database directories) for each database and it works well. You need to do more manual work for applying patches for all software installations (unless you use automatic provisioning of some sort), but you win in flexibility to patch/upgrade only selected databased in the server instead of all. Regarding different users for each database - this may be useful if you want fine-grained separation of duties - by database. However this approach will be useless if all your DBAs have access to all accounts anyway, in this case you will just make your life harder without gaining any benefit. So you should figure out if you really need all your Oracle installations under different unix usernames and whether the benefit outweighs the maintenance overhead. In summary (YMMV): - different oracle homes for each instance - YES - different unix user for each oracle installation - NO ( use single unix user and separate environment files for each instance ). -- Regards, Tanel Poder http://blog.tanelpoder.com <http://blog.tanelpoder.com/> _____ From: oracle-l-bounce@xxxxxxxxxxxxx [mailto:oracle-l-bounce@xxxxxxxxxxxxx] On Behalf Of Andrew Kerber Sent: Thursday, January 03, 2008 21:56 To: satheeshbabu.s@xxxxxxxxx Cc: oracle-l@xxxxxxxxxxxxx Subject: Re: Server Architecture It does sound like a real maintenance nightmare. What is the problem they are trying to solve that requires 5 identical sets of binaries under 5 different users, as opposed to (worst case normally), 1 set of binaries and 5 instances? On Jan 2, 2008 11:49 PM, Satheesh Babu.S <satheeshbabu.s@xxxxxxxxx> wrote: All, We have been proposed with following architecture by our consultant. I need your expert opinion on this. Assume a server got 5 database and all the databases running in same oracle version and patchset. They are proposing to create 5 unix account. Each unix account will have one oracle binaries and corresponding oracle DB. Apart from that each unix account will have dedicated mountpoints. In broader sense each unix account will be logically considered as one server.