Although it has chiefly been known as a desktop Linux distribution, Ubuntu has been gaining ground in data centers as well, according to the latest statistics from web survey outfit W3Techs.

In figures compiled on Thursday, 7 per cent of all the world's web servers were found to be running Ubuntu, up from 5.5 per cent the previous year.

Although that might sound like a mere drop in the bucket, it's actually a very solid showing. By comparison, just 3.4 per cent of web servers were running Red Hat; 1.2 per cent were running Red Hat's community-maintained cousin, Fedora; and a mere 0.8 per cent were running Suse.

When the figures are limited to include only those websites that use some flavor of Linux, Ubuntu now commands 21.4 per cent of the market, with Red Hat, Fedora, and Suse trailing with 10.5 per cent, 3.7 per cent, and 2.4 per cent, respectively.

That's impressive, considering Ubuntu was launched in 2004 and Canonical, its parent company, has only offered a separate server version since 2005. By comparison, Red Hat has been marketing a commercial Linux distribution since 1995.

The W3Techs numbers offer no explanation for Ubuntu's server-side success, but it's safe to say that Ubuntu's easy installer, its solid hardware support, and its rich and reliable software package system all play a role.

And, of course, Ubuntu is free – a fact that cannot be ignored, given the other figures revealed in W3Techs' survey.

According to the latest numbers, the most popular distribution for websites running Linux – with 32 per cent of the market – is actually Debian, a free, community-maintained distro that follows a strict Free Software ethos. (Ubuntu itself is based on Debian, but adds a little polish.)

In second place is CentOS, the free, community-maintained clone of Red Hat Enterprise Linux, with a 27.8 per cent share. Ubuntu comes in third, but it seems unlikely that it would do as well if it didn't match Debian and CentOS on price.

Significantly, however, neither Debian nor CentOS has experienced the same kind of growth that Ubuntu has enjoyed over the past year. Debian installations have been gaining, but only at a very slow pace, while use of CentOS is actually down nearly half a percentage point from a year ago.

Of course, the W3Techs numbers aren't perfect. The survey couldn't identify which OS many websites were running, which suggests that many Linux installations of various types may have gone unreported.

One figure in particular stands out, however. Although W3Techs was able to confirm that 32.8 per cent of all websites worldwide were running Linux, 35.8 per cent were identified as running Microsoft Windows – a disheartening figure that puts Ubuntu's 7 per cent to shame. ®