VMware Opens Up ESX Server Code to Partners

by Timothy Prickett Morgan

Server and workstation virtualization software provider VMware this week announced that it would be opening up the source code to the family jewels in its software portfolio--the hypervisor at the heart of its top-end ESX Server. But don't get too excited about the EMC subsidiary taking on the open source Xen virtualization project in a head-on maneuver. Only key OEM partners--server makers, operating system suppliers, and others who create X86/X64 platforms--are going to get access to the ESX Server source code.

In the announcement, VMware was very clever in that it quoted the CIOs of two prominent customers using VMware's virtualization software to consolidate their server platforms, but customers will never get their hands on the source code. According to Raghu Raghuram, senior director of strategy and market development at VMware, only key partners that apply to the VMware Community Source project will be able to see the source; eventually, says Raghuram, VMware plans to extend the Community Source project to academic institutions, but there are no plans to allow end-user customers to partake of the source code. Obviously, those companies and academic institutions who do get access to the source are going to have to demonstrate that they can protect VMware's intellectual property.

Raghuram explains that VMware was opening up ESX Server for a number of different reasons, and he was not interested in debating the merits of going fully open source. "I don't want to comment on open source as a business model, but I want to discuss how what we are doing allows us to provide deep integration for our customers," he says. While the VMware Community Source effort obviously falls short of the fully open-sourced Xen project, it is more open than Microsoft's Virtual Server 2005--which is absolutely closed--and even goes a lot further than the Shared Source initiative that Microsoft launched in May 2001 for Windows--not coincidentally at the same time that the open source Linux operating system was building up a head of steam. With Shared Source, Microsoft allowed select partners and academics to view the source code to Windows, but it was a read-only affair. Neither Microsoft nor VMware want to let their code roam free on the Internet, and they certainly do not want to create an open source development model in the strictest sense of those words (perhaps the unstrictest sense is a better way to put it).

What VMware is trying to do, explains Raghuram, is allow partners who want to do innovative things with a virtual machine--such as embed them in a set top box, a PC, a server operating system, or any piece of hardware that supports the X86 instruction set--to have a chance to do that. In principle, the community source project at VMware will allow customers to create "black box" modules that plug into ESX Server to extend its functions, or conversely, to embed ESX Server in their own devices to extend their functions. The source is not just a read-only affair, however. If you are part of the VMware Community Source project, you can help suggest changes to the source code and you can help VMware establish interfaces into the hypervisor at the core of ESX Server that might allow it to better integrate with your device or software. VMware hopes that the community will spur innovation, and pick up the pace for deploying virtual machine technology in devices of all kinds.

There is no licensing fee or charge to participate in the community, and those companies who do participate can turn around and sell commercialized, closed source versions of the ESX Server product to their customers--presumably after hammering out licensing fees for their customers and royalties to VMware. Raghuram says that the company has no plans to create an open source community for vendors and academics around its VMware Workstation, ACE, or GSX Server products.

In addition to launching the ESX Server source initiative, VMware also announced today that it was trying to coerce the X86 ecosystem into creating what it is calling an Open Hypervisor Standard. Processor and chipset makers Intel and AMD are participating in the VMware Community Source effort, as are server makers Hewlett-Packard, IBM, and Dell; networking gear suppliers Cisco Systems and Mellanox, operating system suppliers Novell and Red Hat; performance and system management software suppliers Computer Associates and BMC Software (as well as IBM); middleware maker BEA Systems; and other IT players such as Broadcom, QLogic, Emulex have all signed on to the effort. VMware is contributing an existing framework of virtual machine interfaces that it has developed, called the Virtual Machine Hypervisor Interfaces (VMHI) spec, to the standardization effort.

VMware needs standards because standards level the playing field for itself and all customers in the X86 ecosystem. VMware's sales will not be helped if the industry splits into three different and incompatible virtual machines--ESX Server, Virtual Server 2005, and Xen. What VMware correctly points out is that even if these programs are radically different, the one thing the IT vendors and their customers need is a consistent set of interfaces to the hypervisor so a server, a PC, a systems management program, or an application that is virtual-machine aware can access a consistent set of interfaces. If a management tool can manage ESX Server, it should be able to manage Xen or Virtual Server, for instance.

Of course, neither the Xen community nor Microsoft have signed on to VMware's standardization effort. But with the industry heavyweights behind the effort, this is probably only a matter of time. VMware's approach is also going to make it easier for Microsoft and the Xen community to join. Raghuram says that where an existing standards body exists--such as the Distributed Management Task Force (DMTF) for systems management application standards--VMware and its standardization partners will push VM standards through those bodies. Where no standards body exists--such as in the area of virtual machine formatting that would allow portability across platforms--Raghuram says the industry may have to work together to create one.