A tale of 3 OpenStack clouds : 50,000 cores in production at CERN

The CERN IT department provides services for around 11,000 physicists from around the world. Our central services provide the basic IT infrastructure that any organisation needs from e-mail, web services, databases and desktop support.

via http://openstack-in-production.blogspot.jp/2013/09/a-tale-of-3-openstack-clouds-50000.html