Hullo
I can see value in virtualizing small Oracle instances. However, unlike SQL Server, Oracle's architecture and commercial terms favour large, single instance installs, and I can see some challenges with larger scale virtualization:
you've got to track all Oracle instances in the estate under the terms of the licence agreement
I think that the licensing terms mean that every Oracle instance on an ESX server would incur licensing and support costs for every physical CPU on the server.
cache cannot be shared between Oracle instances
There's a higher admin cost of multiple Oracle installs.
RAC's scaling and failover capabilities are tailored to the DBMS' needs and ought to be more effective
Production Oracle installs actually span multiple machines, which need to be treated as a single entity - I don't think that virtualisation is much worse than native install here, unless someone accidentally moves one of the VMs with that whizzy GUI.
I guess that the maximum VM size is quite small for a large DB, too. Conversely, overall Oracle performance may be better in a virtualised environment, rather than consolidated if the DBMS performance is non-linear.
Has anyone done any analysis of whether it is always worth virtualising Oracle? Is there a cutover point? Is it beyond the size of the largest organisation ?
Tim