"Overlay Opportunistic Clouds in CMS/ATLAS at CERN: The CMSooooooCloud in Detail"
By: Jose Antonio Coarasa Perez, CERN
The CMS and ATLAS online clusters consist of more than 3000 computers each. They have been exclusively used for the data acquisition that led to the Higgs particle discovery, handling 100Gbytes/s data flows and archiving 20Tbytes of data per day. An openstack cloud layer has been deployed on the newest part of the clusters (totalling 1300 hypervisors and more than 13000 cores in CMS alone) as a minimal overlay so as to leave the primary role of the computers untouched while allowing an opportunistic usage of the cluster. This presentation will show how to share resources with a minimal impact on the existing infrastructure.