Effort is under way to get virtualization into the Linux kernel, so it can catch up with rival OSes in server efficiency.
SWsoft is trying to get OpenVZ made part of the mainstream Linux kernel--the software at the heart of the operating system--and a part of the major commercial Linux versions, said Kirill Korotaev, a project manager at the Herndon, Va.-based company.
In this, it has a major ally: Red Hat, the top seller of the open-source operating system, which plans to add the software to its free Fedora version of Linux for enthusiasts.
Acceptance into the kernel would likely bring major Linux backers to OpenVZ. But the effort faces a number of challenges, analysts say.
The companies' move to make OpenVZ partitioning standard in Linux is timely, said Pund-IT analyst Charles King.
"I believe virtualization is a current or coming fact of life for every information technology vendor," King said. "Vendors who figure out how to easily integrate virtualization features into their solutions will have a leg-up on competitors."
Over the years, new ways to carve a single server into separate sections have been introduced. Such divisions make it easier to run multiple independent tasks on a machine, keeping it gainfully employed instead of letting it idle through operational lulls. That increase in efficiency means collections of underutilized servers can be replaced with a smaller number of machines, lowering administration and operation costs.
Many of the several ways to subdivide a server rely on virtualization, which breaks the hard link between software and the lower-level software or hardware on which it runs. The software's real foundation is replaced with a virtual one, but the operating system or higher-level software thinks it's running on the real thing.
Using its own take on virtualization, OpenVZ divides a single copy of Linux so it appears to be several independent instances of the operating system, from the perspective of higher-level software. Separate domains, called virtual private servers, can be independently rebooted--though in reality, the underlying operating system stays up and running.
OpenVZ's approach isn't new; the same process has been used elsewhere. For example, Sun Microsystems' Solaris was given a similar feature, called containers, when version 10 was launched a year ago. Before that, developers added a related technology, called "jails," to the FreeBSD version of Unix. IBM's Serge Hallyn has been working on jails for Linux, a variation of BSD's jails.
And OpenVZ isn't even the first major virtual private server software project for Linux. That position goes to , an open-source package that's used in Positive Software's FreeVPS product.
But OpenVZ has the advantage over Vserver, said Illuminata analyst Gordon Haff. "OpenVZ is an offshoot of a well-regarded commercial product that's used by quite a few large hosting providers, so it's clearly the more mature," he said. OpenVZ is an open-source underpinning to Virtuozzo, sold by SWsoft, the main backer of the Linux push.
One complicating factor to the acceptance of the OpenVZ virtual private server is another technology, virtual machine software. Recently, servers using x86 processors such as Intel's Xeon and Advanced Micro Devices' Opteron gained new partitioning options through virtualization. First came VMware's virtual machine software, which uses a hypervisor to let multiple independent operating systems run on the same computer.
Now an open-source alternative to VMware is arriving, Xen, whose hypervisor is developed by start-up XenSource with support by major server makers and Linux suppliers.
There's more than one way to skin a cat, and there're several ways to subdivide a server.
Virtualization can be used to fool software into thinking it's running on many pieces of hardware or software, instead of just one. It also governs how resources are shared between those partitioned parts of the underlying "real" hardware or software.
Some partitioning methods--for example, those used in IBM's x460 Xeon server and Sun and Hewlett-Packard Unix servers--divide a machine into separate physical domains without virtualization. Each hardware partition gets its own hardware resources and operating system.
Virtualization shows up in IBM's Unix servers and mainframes, in which low-level software called a "hypervisor" governs access to hardware resources shared by several copies of the operating system.VMware's virtual machine software uses a hypervisor to let multiple independent operating systems run on the same x86 chip-based server.
Xen, whose hypervisor was developed by start-up XenSource with support by major server makers and Linux suppliers, is an open-source alternative to VMWare. -- Stephen Shankland
Technically, Xen and OpenVZ are complementary; the first lets several independent operating systems run on a server, while the second subdivides a single instance. But in practice, their similar goals means there is some overlap.
Indeed, Novell is focusing just on Xen and has no current plans to use either OpenVZ or Vserver, said company spokesman Kevan Barney.
"Virtualization is the No. 1 customer request for our next generation of Linux enterprise products. We're delivering the Xen 3.0 hypervisor as part of Suse Linux Enterprise Server 10 this year," he said.
"We're constantly researching the virtualization space and will pick other technologies if they meet the needs we've identified," he added. "At this time, neither of these projects (OpenVZ or Vserver) has met our criteria."
But SWsoft hopes that OpenVZ will pick up backing from major distributors of Linux versions, whose products typically use kernels with modifications not in the mainline kernel Linus Torvalds releases.
"Our main goal is to be included in Suse Linux and Red Hat Enterprise Linux," Korotaev said.
Red Hat is a significant ally. "It's interesting to us. We're working with them so they can get their software upstream and into Fedora," Leigh Day, a spokeswoman for the Raleigh, N.C.-based Linux distributor, said. And the company is helping with mainline kernel acceptance as well, she said. "There are some kernel changes that need to be made to implement resource management."
But getting into the kernel will be a challenge. For one thing, Andrew Morton, a top deputy to Torvalds, told CNET News.com he hasn't looked at OpenVZ or Vserver.
Korotaev knows there is work to be done. "It's a long process. We need to have a lot of conversations with Andrew Morton and Linus Torvalds," he said. "I'm not sure it will be easy, because the concept of virtual private servers is quite intrusive to the Linux kernel. The main problem is making clean code that will community will accept."
Becoming open source
OpenVZ has always been governed by the General Public License (GPL), but it didn't become a full-fledged open-source project until last September. Outside help with the software can help steer it in directions customers want and help programmers find bugs faster, Korotaev said.
And unsurprisingly, there's a profit motive involved as well. "We hope to drive more attention to Virtuozzo," Korotaev said. Virtuozzo adds tools for tasks such as managing virtual private servers remotely, backing them up, creating them or moving them from one computer to another without shutting them down.
In the past, although source code was available to those who requested it, as required by the GPL, SWsoft was reluctant to share, Korotaev said.
"There were some ideas about competitors, such as Vserver. We didn't want them to access our code easily," Korotaev said. "Sure, they could get (source code) if they bought Virtuozzo. But when our technology was only started, it was important that our ideas wouldn't appear in another project."
The approach meant SWsoft staff "basically were violating the GPL by not providing the source to their kernel modifications to their customers," said Vserver project leader Herbert Poetzl.
However, Poetzl, who said he declined an offer from SWsoft to maintain OpenVZ, welcomed the Linux push.
"I'm actually very happy that they started this project," Poetzl said. "The competition leads to improvements on both sides, which in turn benefits the customer."