Although it was not supported on older versions, now as of EECS 2.0.6, an Exalogic rack can be configured in a mixed-mode: half virtual and half physical Linux:

• Flexibility to have physical and virtual environments on same rack. For example, production on physical and test/dev on virtual.
• Exalogic Control manages the virtual compute nodes on the rack. Physical compute nodes are managed manually (including PKeys).
• Option to change full physical to hybrid and hybrid to full virtual rack.
• User has an option to choose either the top or bottom nodes for physical or virtual deployment.

For further information about how the compute nodes can be split up on the rack (into bottom or top half) to run either Oracle Virtual Server (OVS "hypervisor") or Oracle Linux, please take a look at MOS Note 1536945.1.

Note: Solaris is not yet supported in the mixed configuration.