XenSource

About XenSource

XenSource emerged from academic research at the University of Cambridge Computer Laboratory, centered on the Xen hypervisor. The foundational work began in 1999 with the XenoServers project, led by senior lecturer Ian Pratt. Pratt, along with his PhD student Keir Fraser, developed the core hypervisor, which allows multiple operating systems to run concurrently on the same hardware. Following the first public open-source release of Xen in 2003, Pratt and Fraser, joined by other Cambridge alumni like Simon Crosby, founded XenSource in early 2005 to commercialize the technology.

The company's core business was providing enterprise-grade virtual infrastructure solutions built upon the open-source Xen hypervisor. It operated on a hybrid business model, offering the Xen hypervisor as a free, open-source component while selling proprietary, value-added products like XenEnterprise. This commercial offering bundled the core Xen technology with management tools, targeting corporate customers in the server and desktop virtualization market. The strategy was to leverage the open-source community for core engine innovation while XenSource focused on building a complete, enterprise-ready product.

XenSource's product, the Xen hypervisor, is a type-1 or bare-metal hypervisor, meaning it runs directly on the host's hardware, providing a more secure and robust foundation for virtual machines. It supports various forms of virtualization, including paravirtualization (PV) and hardware-assisted virtualization (HVM), enabling it to run modified and unmodified guest operating systems like Linux and Microsoft Windows. A key milestone was a strategic partnership with Microsoft to ensure interoperability between Xen-based products and Microsoft's future hypervisor technology. This positioned XenSource as a significant alternative to the then-dominant player, VMware. In August 2007, just as the virtualization market was heating up, Citrix Systems announced its acquisition of XenSource for approximately $500 million. The deal was finalized in October 2007, and the XenSource team formed the core of a new virtualization division within Citrix.