There are numerous advantages to run multiple database instances on the same physical server.
Under Solaris 10 we use the svcs command to provide information about services, including their status.
svcadm issues requests for actions on services executing within the SMF. Actions for a service are carried out by its assigned service agent.
Under Solaris 10 and OpenSolaris the SMF has been upgraded. There are great new tools to handle the sysadmin work on the services.