The Xen.org project backers will jointly adopt much of the Citrix Systems virtual infrastructure in a bid to both improve the adoption rate of Xen inside the enterprise and seed budding cloud suppliers with more open source code. One of Xen's few gains over VMware's dominance in the virtualization field has been its success among cloud suppliers. Amazon's EC2 public clloud uses a version of Xen to run Amazon Machine Images, its required workload format.
Open source code is particularly appealing to cloud suppliers because it enables them to massively scale their facilities without adding licensing expenses.
"Xen.org is putting together a complete virtual infrastructure package," said Ian Pratt, the Cambridge University computer scientist who originated Xen and is co-founder of Xen.org. Pratt is also VP of advanced products at Citrix.
Sun Microsystems, Oracle, Virtual Iron and Citrix all make use of Xen open source code as the basis for a virtualization product set. Pratt said in an interview that a complete virtualization environment, which includes the popular capability of live migration or moving a running virtual machine from one server to another, is available today. "It's a case of selecting which bits get incorporated into a release" of a complete Xen open source infrastructure, he said. He expects that task will be completed in the fourth quarter of this year.
Simon Crosby, CTO of the virtualization and management division at Citrix, said Citrix is ready to donate code toward such a package, and can offer one of only two virtualization infrastructures that have been cited by the Burton Group as satisfying the requirements for enterprise virtualization. Live migration, or vMotion, as VMware has popularized the term with its vSphere 4 product feature, is one of those requirements.
Another key feature, said Pratt, is the ability of the hypervisor to supply virtual switching so that a virtual machine may direct the traffic generated by its application to either the network or to storage, which frequently has a different protocol.
Sun, Oracle and smaller vendors have been building out their own Xen infrastructures, with variations between them. "All had a different service model..." leading to "an inconsistent user experience and a discussion of whose Xen is better. The object now is to remove that discussion," said Crosby in an interview.
Instead of competing on features beyond the hypervisor, Xen backers will share a common infrastructure and compete on management tools and higher level virtualization performance management features, Crosby said. Citrix Systems Essentials product line, which manages Xen-based virtual machines, will not become open source code and will continue to be a competitive product line, he said.
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