Xen is an open source virtualization server widely used in IT. It provides simple and robust commands to manage Xen environment for managing virtual hosts.Backup and recovery of virtual hosts are simple. It can be managed remotely with XenCenter. It supports all client OS like windows, linux etc !!
Room for Improvement:
It requires system with large number of CPUs and large number of memory to support guest operating systems. Not able to export virtual hosts in other virtualization softwares.
Use of Solution:
I have been using Xen for 4 servers now and still using it.
Highly recommended and suited for administrators having sound knowledge of open source commands. !!