NEW ORLEANS—The open-source Xen hypervisor project was once the only major virtualization technology on Linux. Over the years, its prominence and its community faded, but thanks to a spirited set of initiatives, Xen is now back. In a session at the LinuxCon conference here, Lars Kurth, chairman of the Xen Project Advisory Board, detailed his project's path from the edge of oblivion to once again being a prominent, well-respected and growing open-source technology.

Xen started out as a project from the University of Cambridge, gaining the interest of IBM, among others, in its early days. The commercial company XenSource emerged out of that University of Cambridge effort and was acquired by Citrix in 2007 for $500 million. For a number of different organizational reasons, Citrix did not properly engage with the open-source community early on, which led to a number of major Linux distributions abandoning it in favor of rival virtualization hypervisor KVM.

Kurth noted that today, even after some Linux distributions have left Xen behind, Xen has more than 10 million users and some impressive deployments. The Amazon Web Services (AWS) cloud runs on Xen, as does the Rackspace Public Cloud.

Why Xen Was Failing

There were a number of key reasons why the Xen project was failing, according to Kurth. One of the biggest issues was that the project, until recently, had unwritten rules about how it operated. In addition, there were undefined roles; for example, there were no rules on how someone could become a committer to the project. Plus, Kurth said, the project had no road map nor any release planning.

"All that meant it was hard to join the project, vendors got frustrated, and it was hard to work with the Xen project in general," Kurth admitted.

The Fix

"To fix the problem, the project had to grow up," Kurth said.

First, Kurth said, the project started writing down all the rules, so it was clear how it was supposed to operate. All the core contributors for the Xen Project also got together as a technical coordination team and came up with an approach for road maps and release planning.

The final step on Xen's path to redemption was becoming a Linux Foundation Collaboration Project. The Linux Foundation is well-known for its role in fostering the development of Linux. The Collaboration Project extends the Linux Foundation's expertise beyond just Linux to help other open-source projects manage themselves and collaborate better.

The Xen Collaboration Project at the Linux Foundation isn't just about Citrix either. The effort is led by the leading users of Xen including Amazon, Advanced Micro Devices, Bromium, Calxeda, CA Technologies, Cisco, Citrix, Google, Intel, Oracle, Samsung and Verizon. Kurth noted that Xen has been in the Linux Foundation now for six months and the indications are that things are going well, with individual contributions doubling and new interest for Xen from use in mobile networking and automotive use cases.

"We have improved our relationship and trust with our community," Kurth said. "Our developers care about users now, and as a consequence Xen is becoming easier to use."

Sean Michael Kerner is a senior editor at eWEEK and InternetNews.com. Follow him on Twitter @TechJournalist.