At least in IT, perfection cannot be achieved: Every solution inevitably yields new problems. In keeping with this pattern, virtualization was a solution, but it created a problem—the unbridled proliferation of virtual environments, a herd of invisible horses that must somehow be corralled.
In some cases, software intended to manage physical computers was extended with the ability to manage both physical computers and VEs. OEM Ops Center is an excellent example. New software such as OpenStack was also designed from the ground up to manage VEs and their surrounding infrastructure. Understanding these tools is a prerequisite to successful deployment of virtualization.