Data centers are routinely and unknowingly missing a great portion of their entitlement from virtualization. Beyond virtualization's undisputed IT benefits – from reduced rack footprint to disaster recovery – is the parallel story of a substantial benefit from optimizing the physical infrastructure that supports it. In particular, row-based cooling, correctly sized power and cooling, and real-time capacity management are essential elements in realizing virtualization's full potential in cost reduction, efficiency, and reliability.