European enterprises are adopting open source software on the grounds of quality and flexibility, rather than merely considering it "good enough" because it is inexpensive, according to a new survey from research firm IDC.

Besides confirming the widespread use of open-source in important corporate deployments, the survey challenges many received notions about open source in business, said IDC analyst Bo Lykkegaard.

The study, snappily entitled Western European End-User Survey: 2005 Spending Priorities, Outsourcing, Open Source, and Impact of Compliance, found substantial levels of "significant" open source deployment in the 625 companies surveyed, all of which had more than 100 employees. Twenty-five percent said they had significant open-source operating system (Linux) deployments - the other three options were limited deployments, running pilots or having the software under consideration.

That, however, was outstripped by the proportion with significant open-source database deployments, at about 33 percent, according to Lykkegaard. Databases, rather than operating systems, now seem to be leading open source into the enterprise, and could pave the way for more open source, he said. "Companies are increasingly talking about open-source 'stacks', giving you a full open-source infrastructure to run applications on," he said. An example is the LAMP stack, he said - Linux, Apache, MySQL and PHP or Perl.

Despite the press they get, open-source development environments such as Eclipse didn't make a significant showing in the survey, Lykkegaard said.

Open source is often portrayed as a low-cost commodity, with its emphasis on standardisation. Proprietary companies such as Microsoft, with expensive R&D efforts, have argued that open source development replicates existing ideas rather than innovating. But the survey found that the industries perceiving software as the most important to their ability to compete - such as telecos, which rely on software to provide their core services - also had the highest rate of open-source adoption. Other industries with high open-source adoption included financial services and business services.

Conversely, industries that treated software as a commodity were less likely to have open-source deployments.

Companies did not cite low cost as their main reason for deploying open source, a factor usually considered one of the main reasons for open source's success. Rather, companies said open source's top benefit was the flexibility allowed by the open-source licence. "The most important motivator was that they could deploy whenever they wanted, without having to go back to the vendor and negotiate over licences, without having to discuss it with the CFO or looking at the cost implications. They could just do it," Lykkegaard said.

Another surprise was that many companies said the ability to customise open-source software was important. IDC didn't suggest this as one of the standard multiple-choice answers. Instead, many companies added it in the "comments" section of the survey. Vendors of pre-packaged, proprietary software routinely downplay the customisability of open-source, arguing customers are not interested in extending software themselves.

"These companies don't want to start building an application from scratch, but they can build their own additions to an already-complete application," Lykkegaard said. "Because they are part of an open-source community, they can feed this back into the software and it can become a part of the next release, meaning people are helping you to maintain your customisations." He said many companies turn to customisations when they can't find commercial software that meets their needs.

Open-source adoption varied from country to country, with the UK in the middle rankings. Germany and Spain were in the lead, followed by the nordic countries, with France the most hesitant to adopt open source.