"hypervisor" that lets a single machine run multiple operating systems, a feature that's handy for consolidating work onto a smaller number of more efficiently used servers. However, while Linux runs relatively well on Xen, Windows' networking performance on Xen today is, charitably speaking, pokey.
The Xen modification, jointly developed by Intel and Novell, fixes this problem and boosts Windows' network speeds in a virtual machine nearly to that of the operating system running on a physical machine, said Carlos Montero-Luque, vice president of product management for Linux and open platforms business at Novell.
"Without it, network performance is very, very slow--less than 10 percent of (physical machine) speed. With it, we reach over 90 percent speed of a physical machine," Montero-Luque said.
The partnership highlights both the technical hurdles in the way of virtualization's promise and the cross-company work that can be important to getting over those hurdles. Virtualization involves many different layers of the technology stack, including a computer's hardware, the hypervisor, the operating system and management software.
To run on Xen, Windows still requires virtualization support available in newer x86 chips--Intel Virtualization Technology (VT) or Advanced Micro Devices' equivalent, AMD-V. But the new software enables network and disk access to run much more quickly, said Dirk Hohndel, chief technologist of Intel open-source technology center.
"Think of it as the host (Xen) operating system getting out of the way," Hohndel said. "The guest (virtual machine) operating system gets access to the device."
Novell is releasing the software in an open pilot project with its, Montero-Luque said. It will be released to all customers with Service Pack 1 of SLES 10, due to ship this spring with Xen 3.0.4, he said. The software works either with Intel's VT or with AMD-V, he said.
In addition, Novell plans to announce that through its, rival Microsoft will provide joint technical support for customers running Windows Server 2003 R3 atop a platform of Xen from SLES.