We recently worked with EMC's internal IT organization to study the performance of their largest Oracle RAC instance on vSphere 5. The results revealed that Oracle RAC, when virtualized with vSphere 5, performed within 7% on average of a corresponding physical environment. The chart below highlights the results from these tests.
The blue bars are for tests done at a regular level of load and the green bars are for tests done at a 2x level of load. Results are reported in terms of sum total response time in seconds for the variety of different transactions in the tested workload.
For full details about the tests please refer to the paper – Performance Study of Oracle RAC on VMware vSphere 5.
This paper also provides the performance best practices developed and implemented for Oracle RAC on vSphere 5 for these tests. This information can be used to optimize existing and new installations of Oracle RAC on vSphere.