From the Apache CloudStack Documentation:
"CloudStack is an open source software platform that pools computing resources to build public, private, and hybrid Infrastructure as a Service (IaaS) clouds. CloudStack manages the network, storage, and compute nodes that make up a cloud infrastructure. Use CloudStack to deploy, manage, and configure cloud computing environments."
- Using XenServer on Apache CloudStack from the Apache CloudStack documentation
- CloudStack Wikipedia entry
- Ceph, Xen, and CloudStack as delivered at Xen Project User Summit 2013
- Proposal to provide direct support for Xen Project on CloudStack