Ubuntu is no longer merely the desktop Linux distribution of choice anymore, if a new survey is to be believed.

Nearly 7,000 businesses were surveyed by Canonical and open-source analyst firm RedMonk, and it found that the majority are using Ubuntu Linux for a range of mission-critical workloads that are typically run on servers, such as proxy/caching, routing, mail security, clustering, virtualisation, data backup and databases.

While this doesn't mean enterprise Linux leader Red Hat should worry yet that Ubuntu will cut into its business, the survey does lend credibility to Ubuntu's use as an enterprise OS, said Stephen O'Grady, analyst with RedMonk.

"It's not a validation that they've arrived or are ready to compete head-to-head with Red Hat for each enterprise account," he said. "But it does put lie to the claim that Ubuntu is nothing more than a desktop OS."

O'Grady said the range of applications for which companies are using Ubuntu will surprise some people. "The workload distribution is all over the map," he said.

He also said that while the survey covered more small businesses than enterprises, the size mix of companies surveyed was broad, and companies in all ranges reported using Ubuntu beyond the desktop.

Canonical, the commercial sponsor of Ubuntu, co-sponsored the survey and posted a brief blog post about the results. Businesses surveyed were from all over the world, but primarily North America and Europe.

Ubuntu, a derivative of Debian Linux, was first introduced in 2004 but has become the most popular non-commercial Linux distribution in just a few years. Ubuntu's popularity as a desktop OS even inspired hardware maker Dell to begin selling it on PCs, although it's certainly no threat to Windows in that market yet.

Ubuntu's popularity has been buoyed by increased customer interest in netbooks, or mini-notebook PCs, as it is the main Linux distribution shipped on those devices.

Netbooks also run Windows XP, since Windows Vista's hardware footprint was too big for most netbooks. But Microsoft cited growth in the netbook market, which is cutting into the PC market, as a reason the company missed financial expectations for its second quarter. Microsoft said this week that all versions of Windows 7 will run on netbooks, which should boost the OS's profile on these machines.