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VMware moves to deflect Xen, Microsoft

Attempting to maintain its leadership in virtual-machine software, company agrees to share code with partners such as IBM and HP.

VMware made two moves Monday to try to maintain its leadership in the market for virtual-machine software--potentially at the expense of two rivals, Microsoft and the open-source Xen project.

First, the company launched an effort to make its software interfaces into standards that rivals can use, a move that could simplify adoption of emerging virtualization technology. Second, VMware agreed to share the code of its virtual-machine software with business partners such as IBM and Hewlett-Packard, a move the EMC subsidiary hopes will let them customize the software for their own products or extend it for the benefit of all customers.

VMware signed up a major list of allies in the standardization effort--including most of Xen's major corporate allies, IBM, HP, Red Hat, Novell, Intel and Advanced Micro Devices. However, it's not clear how well the standards effort will catch on, because at least so far, Microsoft and Xen themselves are missing from that list.

Standardizing such interfaces "would be good news for the industry," said Illuminata analyst Gordon Haff. "VMware's being smart in taking a leadership position here, but it's a long way from companies agreeing in principle that something is needed to hammer out the details in practice." Red Hat and Novell in particular, however, could help exert pressure on Xen, he added.

Microsoft, for one, showed no signs of being an eager VMware partner. "We've already released all the common APIs" (application programming interfaces) to its VMware competitor, Virtual Server, Microsoft product manager Jim Ni said in an interview on Monday. "You can do anything you want from a management or administrative perspective."

"VMware's being smart in taking a leadership position here, but it's a long way from companies agreeing in principle that something is needed to hammer out the details in practice."
--Gordon Haff, analyst, Illuminata

Simon Crosby, vice president of strategy for a start-up called XenSource that's trying to commercialize Xen, viewed VMware's move as defensive. "They've been viewed as a closed, proprietary code base. They've been under a huge amount of pressure from the fact that the Xen community is very strong, very robust and growing very fast," he said.

VMware Chief Executive Diane Greene said the company didn't invite Microsoft or Xen contributions, but added, "We're more than happy to have them join up. They will be welcome to adopt these standards." Indeed, she expects they will. "Our product experience is so much vaster than theirs. These are solid, customer driven, technology-driven (interfaces). This should be very helpful to them."

Whether at VMware or its competitors, much of the business activity in virtual-machine software is moving from the virtualization task itself to higher management levels. Also Monday, at the LinuxWorld Conference and Expo, virtualization company Virtual Iron said its management software would be able to govern virtual machines running on a Xen foundation as well as its own.

Virtualization in action
Virtual-machine software permits several independent copies of an operating system to run on the same server, ideally leading to greater efficiency, better flexibility and lower cost. The technology is common on mainframes and Unix servers, but VMware got the jump on the market for the vastly more common servers using x86 processors such as Intel's Xeon and AMD's Opteron.

VMware's lead is threatened, however. First, Microsoft purchased Connectix in 2003 and has released the resulting Virtual Server and Virtual PC, which work similarly to VMware's product.

Next, Xen burst onto the scene in the last year, gathering engineering support from server makers IBM, HP and Sun Microsystems and from Linux sellers Red Hat and Novell. Xen founder Ian Pratt helped launch XenSource, which plans to sell Xen support and management tools.

VMware's software works by providing a complete mock-up of the underlying hardware, an approach that permits use of unmodified operating systems. Xen, however, explicitly requires an OS be aware of the virtualization layer beneath it, an approach called paravirtualization that offers a performance boost.

VMware's three interfaces
VMware is releasing and trying to standardize interfaces for three parts of its software, said Raghu Raghuram, senior director of strategy and market development at VMware. The company plans to bring them to standards groups, or, if appropriate, form new standards groups, he said.

First are the management commands used to start or stop a virtual machine or move it from one computer to another, a set of interfaces that already are available. Second, coming within 60 days is the format of a virtual machine when it's saved to disk--a possibility when stopping a virtual machine or saving its state as it's running, for example. Third is "hypercall," the communication method between the virtual-machine software and the operating system running atop it. VMware disclosed that interface to Xen programmers at the Ottawa Linux Symposium in July.

Hypercall essentially describes the commands used in the paravirtualization process. VMware said its flagship software, ESX Server, will permit the use of operating systems that support paravirtualization. "We view paravirtualization as another operating system interface. We will support it just as any other operating system interface," the company said.

XenSource's Crosby said standardizing management interfaces through a standards group such as the Distributed Management Task Force, as Raghuram said VMware might, would be "terrific." On the other hand, XenSource CEO Moshe Bar said Xen's paravirtualization communication protocol is much more efficient than VMware's.

As for the storage method, Xen simply uses standard Linux compression software, and Microsoft in April said it would license its own disk format, called Virtual Hard Disk, for free.

Besides the open interfaces, VMware hopes it will boost its fortunes through sharing its software's underlying source code with its business partners. The sharing program is called the Community Source program.

Some partners are expected to add "black box" software modules into their own versions of VMware, letting them differentiate their products from others', Greene said. Others are expected to add features that will be shipped with VMware's general products. "Overall, we think it's going to allow a lot more innovation," Greene said.

The sharing stops several steps short of that employed by the open-source movement, which creates Linux, Xen and countless other products through a collaborative process that also lets customers download and use the software for free.

But VMware's approach balances that openness with confidentiality, Greene said. And there are significant allies in the code-sharing plan, including Cisco Systems, BEA Systems, IBM and HP, she said.

Catching up to VMware
VMware has made a tidy business out of virtual machines. In EMC's most recent quarter, the subsidiary garnered $91 million in revenue, a 70 percent increase over the year-earlier quarter.

Microsoft has major market power, though, and believes virtualization is best handled as an operating system feature, not a standalone product. "Virtualization is something that belongs in the operating system," Ni said. "As customers look at virtualization services, they'll ask, is it part of the OS? And who's the OS vendor out there I really trust? And wouldn't I get it from them?"

But Microsoft has some work to do. Virtual Server is in the market now, but the company is pinning much of its hopes on a successor that takes the same paravirtualization approach as Xen. Virtual Server today runs on top of a copy of Windows, but the forthcoming Windows Hypervisor will, like Xen, run below it and directly atop the hardware.

The Windows Hypervisor will debut with a version of Windows currently code-named Longhorn Server, due in 2007. However, Ni said, it might well debut with an update or service pack to Longhorn Server, not the initial version of the operating system.

If Microsoft misses the initial Longhorn Server launch, it could have a long wait to introduce a major new feature such as a hypervisor. The company said on its Web site that it plans to issue "a release update approximately two years after each major release."

Xen, too, has some catching up to do. Although the project has been anointed by major Linux sellers, the software still is relatively immature. Programmers have been making progress with new features, though, including the addition of multiprocessor support.

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