Industry observers agree that built-in hypervisors are likely to be a significant threat to VMware's bread-and butter business. But that doesn't mean companies should start pulling the plug on their VMware installations.
"Operating system vendors want to see virtualization as a feature, but to the enterprise customers using VMware, that's not always the case," says RedMonk analyst James Governor. "It's a strategic platform to many of them. You can see that if you look at the job ads from many of the financial services companies--they're not asking for Windows skills or Linux skills, they're asking for VMware skills. Organizations are mature now in their use of Windows and Linux, and they're looking for more effective ways to run those on their boxes."
VMware has responded to the emergence of free competitors by dropping charges for some of its more basic software and specifications; VMware Server and Player are both free, for instance, and its Virtual Machine Disk Format specification is now available without license. It has also begun buying companies to bulk up its portfolio of management and administration tools, beginning with Akimbi in June. Akimbi makes tools for virtual lab automation, configuration management and self-service provisioning.
Do you need it?
Virtualization may soon be
everywhere, but that doesn't mean it's for everyone. There are inherent
limitations to the technology--such as the overhead involved--which make it
unsuitable for workloads with heavy, continuous processing or I/O demands.
Microsoft's Biehler points to four key uses for virtualization: server consolidation in the data centre and branch office; consolidating and re-hosting legacy applications; automating and consolidating software test and development environments; and simplifying disaster recovery planning. "If your requirements are one of those four, it's worth considering virtualization. If not, it's worth first validating whether it really makes sense to virtualize."
More important, though, is to remember that virtualization is just one means of achieving infrastructure that's reliable, adaptable, doesn't cost a lot and is easy to manage. Virtualisation may be a part of the way to reach that goal, but many companies may find they really just need to address more basic problems.
"When you move to a virtual environment, that doesn't mean it's more efficient," says Gartner's Dawson. "If you take a pile of rubbish and you refine it, you get refined rubbish. People have to learn that they need to discover their portfolios before they virtualise them. The right approach may be to send it off and not touch it."
Also the level of management discipline found in x86-based data centres is often lacking, compared with that in the mainframe and mid-range worlds, says Ovum's Barnett. "If the environment is subject to little or no management discipline, if you don't have that governance and those processes in place, then actually, virtualisation and clustering are probably not going to help you. You need to sort the mess out," he says.
Just moving to network-based storage may boost reliability so that companies may have little incentive to go further, Barnett says.
That said, the benefits of virtualization will almost certainly ensure its rapid growth for the near future. "VMware now has references for companies using the technology on a decent scale. They can point to people really doing it and benefiting from it," Barnett says. "That is always going to result in an acceleration of usage and adoption. We expect interest in virtualisation to keep accelerating."
Who are the main companies providing virtualization technology and what are there different strategies?
1. VMware: The old hand
VMware dominates
virtualisation for x86 systems, and more or less invented the market others are
now trying to cash in on. Three of its core products are VMware Workstation and
the freely available VMware Server (formerly GSX Server) and VMware Player. The
software runs on Windows or Linux.
Workstation is designed for applications such as software development and testing, while Server is targeted at the data centre, for uses such as testing patches, simplifying provisioning and using virtual appliances. VMware Server was released in July, replacing ESX Server. VMware Player runs virtual machines created by other applications--including Microsoft's VirtualPC--but can't create its own.
Those products need a host operating system to run on, while VMware's flagship ESX Server drastically increases performance by eliminating the need for a host. Instead, ESX uses its own stripped-down kernel, and runs on bare-metal servers. The approach allows support for more guest virtual machines, but the ESX kernel doesn't have as broad support for hardware.
VMware Infrastructure 3, released in June, includes ESX Server, VirtualCenter management tools, Virtual SMP (symmetric multi-processing) up to four-way, VMotion, VMFS distributed file system software, and new tools such as Distributed Resource Scheduler and High Availability and Consolidated Backup. VMotion allows guest virtual machines to be transferred from one physical system to another without interruption, and can be used for things such as hardware maintenance and load balancing.
"Companies are no longer treating servers as a single entity, they're treating them as part of a giant resource pool," says VMware's Raghuram.
Competitors such as Microsoft and Xen may have achieved a significant foothold in the types of services provided by VMware Server and VMware Workstation, but may not be able to offer anything comparable to the mature administration tools of VirtualCenter for some time. "The ambitions of people like Microsoft and Xen go beyond basic virtualization, but they have a long way to go," says Raghuram.
2. Microsoft: Grabbing a slice
Microsoft offers
Virtual PC--acquired along with Connectix--as its desktop virtualization tool
for Macintosh and Windows. Virtual Server, which requires Windows Server 2003,
was also developed by Connectix, but hadn't yet been released when the company
was acquired.
Virtual Server 2005 R2, the latest version, introduces support for Linux guest operating systems, the ability to make use of (but not virtualise) SMP, support for x86-64 hosts (but not guests), and a redesigned Web administration interface. Virtual Server needs a host OS, unlike VMware's ESX Server or XenSource's Xen Enterprise, meaning significant processing power overhead.
Virtual Server has been demonstrated with support for Intel's VT and AMD's SVM, which will be included in the next release. Microsoft is currently beta-testing Service Pack 1 for Virtual Server 2005 R2, with a Beta 2 scheduled for Q4 2006. Also in development is System Center Virtual Machine Manager, Microsoft's answer to VMware's VirtualCenter, with a release scheduled for this year. The tools will only support Windows guest OSs, leaving Linux support to third parties. In a classic case of Microsoft's thinking on integration, all of Virtual Server's administration tools require technologies like Internet Explorer and Active Directory.
As of April 2006, Virtual Server is available free of charge. Microsoft also made Virtual PC a free download in July, at the same time announcing a that Windows Vista Enterprise's licensing terms will allow customers to install up to four virtual copies of the OS for a single user on a single device. The licence doesn't require use of Microsoft's technology to create the virtual machine.
Most importantly, Longhorn Server--currently scheduled for 2007--will get a built-in hypervisor (code-named Viridian) within about three months of release. The strategy is clear: virtualization, in Microsoft's world at least, will become an operating system feature, just as the Web browser did.
Reviewers have not been overly impressed with Virtual Server so far, but Microsoft believes it's good enough for most uses. "Some customers have niche requirements that might require niche products," says Alfred Biehler, Microsoft UK product manager for management and virtualisation. "For the majority of the market, we believe we've got a good solution. And it will just get better." Microsoft also argues there's an advantage in having the entire operating system and virtualization stack supported by a single vendor.
Microsoft has been paying attention to interoperability issues, say competitors such as Xen. Viridian will use paravirtualisation, and architecturally is very similar to Xen, which should make interoperability easier, according to Simon Crosby, chief technology officer at XenSource.
In June 2005 Microsoft made the specification for the Virtual Hard Disk (VHD) image format (used by Virtual PC 2004 and Virtual Server 2005) available under a royalty-free licence, to help it compete with VMware's proprietary equivalent. "Microsoft has absolutely got the interoperability message," says Crosby.
3. Xen: Old head on new shoulders
On the face of
it, Xen may seem like a newcomer, but the software has been evolving for nearly
four years, and has impressed reviewers with its solidity. Moreover, its open
source approach (it is licensed under the GPL) has helped it toward broad
industry support.
The support of Linux distributors has been key; Xen will be built into versions of Red Hat Enterprise Linux and Suse Linux Enterprise Server arriving this year, among other distributions. With this integration comes automatic certification on all the hardware that those distributions run on, according to Simon Crosby, chief technology officer at XenSource, the commercial company founded by Xen's initial developers. Sun will add Xen support to OpenSolaris this year, and it will arrive for Solaris 10 next year.
The same dynamic has meant that Intel and AMD have both rushed to contribute to the project, meaning it already supports both companies' hardware-based virtualisation, well in advance of Microsoft. (VMware also works closely with Intel and AMD and supports Intel's VT and AMD's SVM.) "Intel has been a major contributor with VT, and that means AMD contributes, because they can't afford not to," says Crosby.
Xen already beats VMware on some basic virtualization features, for instance supporting up to 64-way SMP, to VMware's 4-way limit, Crosby points out.
Such accomplishments explain why people take Xen's ambitions seriously. "We are surrounding ourselves with an ecosystem of players who are economically motivated to work with us," says Crosby. Xen itself only carries out the virtualization part of the puzzle, but its universal availability creates a huge, wide-open opportunity for partners to step in with virtualisation-aware products to handle more advanced management and administration tasks, Xen developers argue.
XenSource itself will be just one of these, with products such as Xen Enterprise, a "bare-metal" answer to VMware's ESX Server. In April Virtual Iron launched version 3 of its virtualization platform, scrapping its own virtualisation engine in favour of Xen.
Crosby argues that Xen's open approach is its main advantage over VMWare. VMWare has an incentive to own the market for tools based on its platform, and its control of that platform means it can kill off competitors at will, Crosby says. By contrast, XenSource says it isn't aiming to own the Xen ecosystem.
Analysts agree this is a big selling point. "Some of the big players may be beginning to feel they've ceded too much control to VMware now. They're nervous about it as a control point," says RedMonk analyst James Governor. But whatever its momentum, Xen has so far barely scratched the surface of the marketplace--it didn't even register in a survey of large North-American businesses carried out by Forrester earlier this year. "Certainly Xen is nowhere near as mainstream as VMware yet," says Governor.
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