According to OpenStack user survey, Ubuntu Linux is the most popular OpenStack operating system. According to Mark Shuttleworth (founder of Canonical, Ubuntu's parent company), 55 percent of OpenStack operating systems are on Ubuntu. To know more about synchronization of Ubuntu and OpenStack, go through the article by Steven J. Vaughan-Nichols, writer about technology.
http://www.zdnet.com/openstacks-top-operating-system-ubuntu-linux-7000027360/