While digging into the last OpenStack User Survey, I found that Ubuntu Linux was the most popular OpenStack operating system.
No matter if users had dozens, or thousands, of CPU cores in their cloud, most preferrred Ubuntu. It was followed by the Red Hat Enterprise Linux (RHEL) clone CentOS, which is now part of the Red Hat family, and then RHEL itself. At the end of the herd, was Windows, Debian, openSUSE and SUSE Linux Enterprise Server (SLES).