Data centers are the backbone of today’s information technologies. With increasing usage of cloud services and web applications, the need for remote computing and storage will only grow. However, one has to consider that increasing numbers of server and storage systems also mean increases in energy consumption. The power demand is caused not only by the IT hardware, but is also due to the required infrastructure such as power supply and climatization. Therefore, choosing the most appropriate components as well as architectural designs and configurations regarding energy demand, availability, and performance is important. This chapter depicts influencing factors and current trends for these design choices and provides examples.