The data center has gone through many major evolutionary changes over the past several decades, and each change has been defined by major shifts in architectures. The industry moved from the mainframe era to client/server computing and then to Internet computing. In 2011, another major shift began: the shift to a virtual data center. This has been the primary driver in enabling customers to transition to the cloud and ultimately IT as a service. The shift to a virtual data center will be the single biggest transition in the history of computing. It will reshape all the major data center tiers: applications, storage, servers and the network.