Businesses are evaluating open-source software the same way they evaluate proprietary software, according to industry analysts.

Enterprises are judging open source on its up-front cost, total cost of ownership, reliability and features, just as they would a commercial product, said Matt Lawton, an analyst with IDC. Criteria unique to open source such as issues of potential liability for patent infringement and the level of technical support, are way down the list of worries.

"Software is software and things like functionality and reliability are the most important attributes, regardless of whether the software is open source or not," Lawton said. "But having said that, to the extent that open source can save end users money, then they are all ears."

If open source is increasingly being considered on par with proprietary software, that opens more opportunities for it in the enterprise market for use in servers, desktop computers and mobile devices.

Worldwide revenue for open-source software, which reached US$1.8 billion in 2006, is expected to grow at a compound annual growth rate of 26 percent, reaching $5.8 billion by 2011, IDC research shows.

Virtualisation is also becoming more widely accepted and deployed in enterprises. Virtualisation is software that divides one server into multiple logical servers, enabling IT professionals to run multiple software applications efficiently on one machine, increasing utilisation rates. A few years ago, companies used virtualisation primarily in software test and development environments, but as they become more confident, companies are using it in production environments, said Andreas Antonopoulos of Nemertes Research.

Virtualisation can be an energy saver because if server utilisation increases to 70 percent or 80 percent from the average 1 percent to 20 percent, fewer power-hungry servers will be needed.

Antonopoulos calls virtualisation the "sardine can" strategy. The idea is to cram as many applications into one server as possible, like squeezing the tiny fish into a can. "That strategy has allowed IT departments to use more software applications ... for the same amount of capital budget," he said.

But datacentre operators may be reaching a point of diminishing return using virtualisation for server consolidation, Antonopoulos said. Companies that have used virtualisation for consolidation for some time may have already reduced the number of servers to as few as they need. For them, other business drivers for virtualisation include easier software development, disaster recovery, business agility and operational efficiency.