Server Architecture

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.

 I am slightly worried about this architecture. Because when this architecture goes to production, the impact it will have on maintenace going to be huge. Assuming i am having minimum 100 db in production( ours is a very large shop) and if i need to apply one patch to all these servers going to kill us. Secondly, will there be a impact on licensing. I don't think so, but like to check it up with you guys. I know it has got some advantage too. But is this approach is suitable for large shop like us?

Regards,
Satheesh Babu.S
Bangalore

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