Chapter 5. Virtualization limitations
5.1. General limitations for virtualization
There is no support for converting Xen-based guests to KVM or KVM-based guests to Xen.
See the Red Hat Enterprise Linux Release Notes at https://access.redhat.com/site/documentation/ for your version. The Release Notes cover the present new features, known issues and limitations as they are updated or discovered.
You should test for the maximum anticipated system and network load before deploying heavy I/O applications such as database servers. Load testing and planning are important as virtualization performance can suffer under high I/O.