"Cloud computing is viewed by many as the next major step in the evolution of computing infrastructure. Very large commercial cloud computing data centers have emerged around the world with petaflops of processing capacity, hundreds of petabytes of data storage, and wideband network access. Services, including electronic mail, data storage, database management, application hosting, very large dataset processing, and high performance computing, are globally available today from many cloud computing data centers. Cloud computing advocates promise on‐demand delivery of these massive, warehouse‐scale computing resources simply and easily through a network browser. Much of the technology and computer architecture that enable modern cloud computing has roots in the mainframe, client‐server, and early internet computing eras. What has emerged in recent years, however, differs from all of these in many attributes. Cloud computing data centers have different capabilities, risks, and security concerns than conventional networks, as well as different cost and efficiency models. These differences are substantial, and have resulted in a wide variety of realistic and unrealistic claims for cloud computing, as well as a good deal of hype and confusion. With the proper implementation and operations, cloud computing data centers have demonstrated as good or better cyber security, capabilities, and cost than is currently available in Department of Defense (DoD) data centers. These improvements, however, are by no means guaranteed for every case and very much depend on the specific details of the implementation and operations."
Office of the Under Secretary of Defense for Acquisition, Technology, and Logistics: http://www.acq.osd.mil/