Free Linux server operating system deployments were predicted to grow faster than the total number of Linux servers placed into service worldwide in the next four years.
A study by the analyst firm IDC predicted a contraction in the number of net new Linux server operating system subscriptions this year, "followed by a steady recovery through 2013".
IDC expected the combined total of paid and free Linux server operating systems to grow at a compound annual rate of 1.1 percent over the period.
But IDC warned this did not take into account growth of Linux operating systems in virtualised environments aboard existing servers, "a metric not directly considered in the predicted growth of net new subscriptions and deployments", the firm said.
"The success of the market is increasingly defined by the installed base rather than by the number of brand new subscriptions or deployments being made," said Al Gillen, program vice president, system software at IDC.
"This phenomenon is not unique to Linux - as we see the same trend playing out with Windows server operating environments.
"We find that more customers are seeing non-paid Linux as a viable solution for certain non-critical business needs, despite the lack of commercial applications and the potential support challenges that come with a non-commercially-supported distribution."
Red Hat and Novell accounted for 94.5 percent of worldwide Linux operating systems revenue in 2008.
They also accounted for 90 percent of new Linux subscriptions in server environments worldwide.