The architecture includes some surprises:
* Its uses Open Source Linux and Eucalyptus as the cloud virtualization environment
* Its KVM based
* 15 PetaBytes of storage (15,000,000 terabytes)
* Single file size limit upto 1 PetaByte
* The same Nebula/IaaS architecture will support sub-clouds/architectures for PaaS and SaaS activities within the Government"
Link to Original Source