If you are managing physical and virtual operating systems, servers, and storage devices within a large deployment, rather than just managing individual systems, you can use the management solutions available in the Oracle Enterprise Manager Ops Center.
With the Enterprise Manager Ops Center you can manage users and roles for the overall data center. You can add existing local users from your individual systems as users in the Ops Center, and you can control what assets and features these users are authorized to use.
For information, see http://www.oracle.com/pls/topic/lookup?ctx=oc122.