When determinism is more important than equal access, virtualization technology can isolate resources for use by a specific guest OS, rather than create virtual I/O for shared access between multiple VMMs.

A key difference between a real-time hypervisor and server VMM solutions is how physical resources are allocated. CPU cycles, RAM, I/O, and interrupts, must be allocated by any VMM. A server VMM multiplexes these resources; a solution that attempts to fairly distribute physical resources among all the virtual machines on a given hardware platform can never support a deterministic RTOS.