As virtualization is becoming a pervasive technology and will soon be deployed in many datacenters it is important to understand on how technologies like RHEL5 Xen are being installed, deployed and managed and optimized for performance. In this talk, we will give an overview of Xen and how to install, configure and manage Xen in Red Hat Enterprise Linux 5 including performance expectations and factors influencing performance. Optimal setup of networks and various storage configuration tradeoffs when installing or optimizing a Xen virtual environment will be explored. Performance measurements of benchmarks and actual applications will be shared as examples of performance optimization. Finally we shared Red Hat's experience in using Xen for high availability with Xen guest migrations w/ shared storage and the GFS cluster file system.