KVM virtualisation gets real momentum

Four months ago, almost nobody had heard of an open-source virtualisation software called KVM. But that was then.

The project, backed by a stealth-mode start-up called Qumranet, uses a technical and cultural approach that has quickly drawn powerful allies — including Red Hat and Linux founder Linus Torvalds.

That success is only a first step in KVM's push to make a mark in virtualisation. But it signals significant influence over the technology, which is spurring a top-to-bottom revamp of the computing industry through its ability to make a single machine behave like many.

But does the world need another virtualisation option? EMC subsidiary VMware rules the roost today. Microsoft is working on a project called Viridian, which is set to debut in roughly a year. And numerous open-source allies have already focused attention on an open-source rival called Xen. While KVM delivers some new options and competition, it also brings new complications.

"In the near term, KVM will cause some pain because of the market confusion and developer dilution it will cause," said Illuminata analyst Gordon Haff. "But in the longer run, better technical options can only be good for Linux and open source."

KVM, which stands for "Kernel-based Virtual Machine", provides a new Linux-based mechanism for splitting a single physical computer into multiple virtual machines. It's going up against another approach, which uses a low-level software "hypervisor" to perform the same virtualisation function.

The industry is scrambling to adopt virtualisation for a range of reasons: so that groups of inefficient servers can be replaced with a fewer machines; so software can be tested in harmless partitions; and ultimately, so data centres packed with computers can fluidly adjust to shifting priorities.

Industry players such as Novell and IBM say they're watching to see how well KVM fares. But Brian Stevens, the chief technology officer of dominant Linux seller Red Hat, believes KVM is viable.

"There's a year of work, I'd guess, to really make it at parity to where Xen is today... But I think it's going to happen," Stevens said. "The [open-source programming] community is really going to gravitate [to KVM] much more so than [to] Xen."

Qumranet has funding from Sequoia Capital and Norwest Venture Partners, but chief executive Benny Schnaider is mum on the company's business plan. In an interview, he said only that Qumranet is "not planning to make money by selling or supporting KVM".

The KVM project started in early 2006, Schnaider said. That's about the same time Moshe Bar left XenSource, the Xen commercialisation start-up that he co-founded. Bar, who now is Qumranet's chief technology officer, declined to comment for this story.

Qumranet is based in Santa Clara, California, with research and development in Israel. (Qumran is an ancient settlement near the caves where the Dead Sea Scrolls were found.) The start-up has more than 30 employees, most of them engineers, Schnaider said. Given that fewer than a dozen are working on KVM, according to lead programmer and Qumranet employee Avi Kivity, it's a good bet that the company has other technology in the works.

Kivity introduced the world to KVM with a 19 October posting to the Linux kernel mailing list. His patch updated Linux so that higher-level software could take advantage of hardware virtualisation features built into the latest processors from Intel and AMD. The result: other operating systems, including Microsoft Windows, can be "guests" running on a Linux host foundation, on newer hardware.

KVM's approach differs from that of Xen, which governs access to hardware using a combination of a lightweight "hypervisor" foundation and a privileged operating system, which is typically Linux.

KVM's method is conceptually closer to one of two approaches used by VMware — the "hosted" model used in the free VMware Server and Player products. In that model, guest virtual machines run atop a copy…