The foundation of Citrix XenServer is the open source Xen hypervisor, a proven and fully supported engine for server virtualization.

What is Xen?
Xen is a unique open source technology invented by a team led by Ian Pratt at the University of Cambridge and developed cooperatively by the world’s best engineers at over 20 of the most innovative data center solution vendors. With Xen server virtualization solutions, a thin software layer (known as the Xen hypervisor) is installed directly on the hardware, or “bare metal,” and is thereby inserted between the server’s hardware and the operating system. This provides an abstraction layer that allows each physical server to run one or more “virtual servers,” effectively decoupling the operating system and its applications from the underlying physical server. Xen’s paravirtualization technology is widely acknowledged as the fastest and most secure virtualization software in the industry and is enhanced by taking full advantage of the latest Intel VT and AMD-V hardware virtualization assist capabilities. The Xen hypervisor is exceptionally lean - less than 50,000 lines of code – which translates to extremely low overhead and near-native performance for guests.

Powering Citrix XenServer
The inventors and lead developers of Xen, with the rest of the XenServer team, take this powerful virtualization engine and build out a full managed server virtualization platform, designed for efficient management of Windows and Linux virtual machines.

Native 64-bit Power and Scalability
Citrix XenServer is a native 64-bit virtualization platform with the scalability required by business-critical applications. The highest host and guest CPU and memory limits available, coupled with fine-grained resource controls for CPU, network and disk, enable it to deliver optimal quality of service.