Interop The virtualization hypervisor belongs in server hardware - not in the operating system. So says Xensource, friend and partner of the operating system giants Microsoft, Red Hat and Novell.

"Hypervisor will be delivered in hardware. In my view, it's a separate layer [from the operating system] because it's part of the box," Crosby told several hundred people gathered for his Interop keynote at the Jacob Javits Center in New York. "Platform virtualization is here to stay."

Since Citrix announced its intent to acquire the company (http://www.theregister.co.uk/2007/08/15/citrix_buys_xensource/) last summer, XenSource's business model has switched gears quite a bit.

In August, the open source virtualization software company announced XenCenter OEM Edition, the industry's first embedded hypervisor. And this week, just days after Citrix closed its $500m acquisition of the company, Dell announced plans to ship XenCenter as an option (http://www.theregister.co.uk/2007/10/23/dell_embeds_xen_hypervisor_in_servers/) on all of its x86 PowerEdge Servers.

On the surface, Crosby's rhetoric appears to contradict XenSource's technical partnership with Microsoft on Viridian, the planned Xen compatible hypervisor for Windows Server 2008.

Yet, behind the scenes, it appears that XenSource, Citrix and Microsoft may be expanding their close partnerships to defeat a common enemy: VMware.

At iForum this week, Citrix announced (http://www.theregister.co.uk/2007/10/22/citrix_iforum_xensource/) two newly named products out of its XenSource group - Citrix XenServer and Citrix XenDesktop - and promised "broad interoperability" with Microsoft's Viridian. Meanwhile, Microsoft today announced plans to extend its hypercall API within Windows Server virtualized. It cited Xen backers Citrix and Novell as partners.

At Interop, Crosby, now head of Citrix's virtualization and management division at Citrix, also reached out to Redmond.

"Microsoft Viridian is based on an implementation of Xen architecture and everything we do will work with Viridian," Crosby said. "We're not trying to create a parallel incompatible hypervisor." ®

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