Leaner virtualization coming to Windows, Linux

Virtualization software that's all the rage today--chiefly VMware, Microsoft Virtual Server and Xen--lets a single computer run multiple operating systems.

Now, a newer variety of virtualization is emerging that employs a lighter-weight approach so that a single operating system can be sliced into independent sections.

While details of the concept are just beginning to emerge, it's likely only a matter of time before it shows up in Windows and Linux. "It's something any operating system vendor has to have," said Serguei Beloussov, chief executive of software maker SWsoft, whose products enable the lightweight approach.

The overall goals of the two approaches are the same: Make a single computer more efficient, divide work among separate non-interfering partitions, and eventually move to a fluid world where software tasks move among computers in response to shifting computing priorities.

The new approach, virtualizing above the operating system, requires less computer memory, permitting dozens of partitions on the same machine in some Linux cases, but sacrifices some flexibility and partition independence.

While servers are likely to be the first place the technology is used, it holds promises for PCs, too, where users could easily create partitions for trying new software, dividing work and home tasks, or isolating potentially risky applications such as Web browsers.

The idea is used in Solaris 10, which Sun Microsystems released in early 2005 with a feature called Solaris Containers. Now it's spreading to other operating systems.

Mike Neil, product unit manager for Microsoft's virtualization technologies, confirmed that his company is working on the lightweight virtualization approach variously known as containers, virtual private servers or virtual environments.

"You'll see that as an evolutionary step," he said in an interview at the LinuxWorld Conference and Expo here last week, though he declined to say when it might become available as a product.

Microsoft is following in the footsteps of SWsoft, a much smaller company whose Virtuozzo product is available for Windows and Linux. And Beloussov says programmers are moving swiftly to build container technology into Linux through a project called OpenVZ, the foundation of Virtuozzo.

Beloussov believes the kernel at the heart of the open-source operating system will soon--likely this year--get some important portions of container technology. It will be "something you can actually use," he said, adding that the company is getting help from Linux sellers Red Hat and Novell.

Increasing the efficiency of computer utilization is the main draw for the technique, Gabriel Consulting Group analyst Dan Olds said. "Tens or even hundreds of low-demand user workspaces can be layered on a few systems," he said. But there's a significant concern in moving critical tasks to containers. "A single operating system kernel is a potential vulnerability. If it goes down, everyone goes down. I think the VMware approach is the better solution for x86-based systems right now," he said.

But SWsoft is making progress. OpenVZ project manager Kirill Korotaev proposed adding some container foundations to the kernel in late March, and received a favorable reply from others including Herbert Poetzl, lead programmer of an OpenVZ alternative called VServer. Korotaev then submitted patches.

But there's work to be done convincing the Linux kernel's top brass, including Andrew Morton, a key deputy to Linux founder and leader Linus Torvalds.

"It's enabling infrastructure which will permit further feature work in the future," Morton said in an interview about the OpenVZ work. "I'd need to get a clearer idea of where it's all headed before supporting the addition of such a thing."

Pricing complications
But like other virtualization technologies, containers introduce yet another complication into traditional software pricing. Standard pricing models assume a single operating system running on a computer with a fixed number of processors.

Containers not only present the appearance of many different operating systems, they raise the possibility of constantly changing numbers.

From SWsoft's point of view, customers only need to pay for one copy of Windows and may subdivide it into as many partitions as they like. "It is a single copy of Windows. We isolate groups of users, files and applications," Beloussov said.

Microsoft--whose financial incentives are opposite to SWsoft's--disagrees completely. "We look at it as each one of those instances is an operating system license," Neil said.

Similar confusion could extend farther up the software hierarchy. For example, when running Web server software, many different containers can use the same copy stored in the same memory location. Does that mean there are several copies of the software or just one on a server?

That complication is one reason some software companies are moving to a different pricing structure. Red Hat, for example, lets customers install as many copies of an operating system as they like on a server. They pay by the number of processor sockets the server has.

With virtualization, however, that approach still has its limitations. For example, Virtuozzo, VMware and Xen all let one apparent instance of an operating system be moved from one machine to another. Some believe therefore that virtualization will push companies toward purchases that permit company-wide software use or, if an appropriate measurement can be found, pricing on the basis of how much work a particular software product accomplishes.

SWsoft knows its challenges include not only technology but competition--in particular Microsoft. In fact, the software giant uses the same Windows containers approach as SWsoft. Both rely on a feature called Windows Terminal Services that today lets several remote users tap into a shared server, with each user appearing to get his or her own operating system.

But SWsoft believes it can stay ahead of the giant, just as VMware has stayed ahead even though Microsoft bought lower-level virtualization software. For one thing, the company has 28 patents in the virtualization area, Beloussov said. For another, much of the hard work in virtualization isn't producing the low-level software, but rather higher-level management tools to govern containers.

It's possible Microsoft could join forces with SWsoft, if SWsoft can stay ahead, Beloussov said. "You have to be able to compete with them so they become your partner," he said.