When it comes to raw number-crunching, we need a distribution that is easy to manage, easy to scale and easy to trust. Stability and predictability trump all the glitz and glamor of the desktop-focused distributions. Debian and Ubuntu top the results this year, with RHEL and CentOS right behind. These are the names we've come to trust, and with high-performance computing, that's what we need.

• Debian 22.5%

• Ubuntu 15%

• Red Hat Enterprise Linux 13%

• CentOS 11.7%

• Other 8.6%

• Gentoo 7.3%

• Linux Mint 7.2%

• openSUSE 5.4%

• Fedora 5%

• SUSE Linux Enterprise Server 3.3%

• Rocks Cluster 1.1%

Popular write-ins: Arch Linux and PCLinuxOS.