4 min read

Microsoft Embraces Open-Source Xen To Run Open-Source Linux

With x86 virtualization gaining ground, Microsoft wants to ensure Windows remains the boss.
Microsoft wants Linux to run effectively under its most advanced virtualization software, an upcoming hypervisor slated to be part of a new version of Windows Server, code-named Longhorn. To ensure that it does, the company entered a technology development partnership last week with XenSource, the supplier of the increasingly popular Xen virtualization engine.

The move was something of an about-face. Xen, like Linux, is open source code, and Microsoft has called open source software a challenge to intellectual property rights. But ignoring the growing strength of Xen in the virtualization market could have been hazardous for Microsoft.

More Than Hype

What is a hypervisor?
An efficient virtualization engine that can generate multiple virtual computers on one physical computer. Hypervisors can host virtual machines using different operating systems running next to each other.

How does it work?
It runs like a microkernel operating system connected to the metal of a chip. There's no intervening operating system, so hypervisors run much faster than older forms of virtualization.

Who has one?
For the x86 world, hypervisors are available from VMware and Xen, with Microsoft planning on delivering one sometime next year.

IBM a few days earlier said it was supporting Xen as it gets added to Suse Linux 10, an enterprise server version of Linux about to be updated by Novell. Chipmakers Advanced Micro Devices and Intel are building support for virtualization, which Xen exploits, into their latest chips. Red Hat has unveiled its own plans to support Xen in the next release of Red Hat Linux.

For Microsoft, the danger signs were sprouting everywhere. Virtualization, the ability to partition a hardware server into multiple virtual software machines, is helping drive the trend toward server consolidation. Microsoft had the option of running with the trend or running into it.

Customers using both Windows and Linux also were asking, "What are you doing to make our lives easier?" concedes Jeff Price, senior director for Windows Server. The right response, it seems, was not another Microsoft "Get the Facts" campaign aimed at Xen. ("Get the Facts" tries to convince IT managers that Windows costs less to operate than Linux.)

Block The Competition
Microsoft appears to have read the tea leaves. It's giving away its own Virtual Server software rather than let open source Xen and competitors such as EMC's VMware steal the Windows virtualization market out from under it. It opened its own Open Source Software Lab to supply research on how to get Windows to work better with more pieces of open source code. And it's promising that additional cooperation will flow between Microsoft and XenSource on management tools to ensure customers can manage multiple Linux virtual machines once they're running on a Longhorn server.

But VMware, the company that leads the market in x86 server virtualization, greeted the Microsoft moves with skepticism and joked about Microsoft's frequently delayed launch date for Longhorn. The first release of Microsoft's hypervisor "is two years away or more," says Raghu Raghuram, VP of platform products at VMware. Microsoft's Price says his company's hypervisor will become available 180 days after the release of Longhorn Server, which is now slated for the end of 2007.

Raghuram calls the Xen-Microsoft agreement a "one-way arrangement where Microsoft will allow Linux to run on future Microsoft hypervisors ... but not the other way around." That is, Windows needs to control the hardware for the Longhorn-Xen technology partnership to work. There will be no reciprocation that would allow Xen to run virtualized Windows on a Linux server, he says.

VMware's products, including its existing ESX hypervisor, run with Linux, Windows, or Sun Microsystems' Solaris as the operating system controlling the hardware.

Still, Microsoft is showing that it's willing to adapt. It recently invested in increased interoperability with JBoss, distributor of the JBoss Java application server, and SugarCRM, the open source ERP application supplier.

Microsoft knows it can't keep Linux and other open source code out of the data center. But if Linux is going to run servers in the data center, then Microsoft wants to make sure they're running under the Windows operating system.