Data center design is a tedious and expensive process. Recently, this process has become even more challenging as users of cloud services expect to have guaranteed levels of availability, durability and performance. A new challenge for the service providers is to find the most cost-effective data center design and configuration that will accommodate the users' expectations, on ever-changing workloads, and con- stantly evolving hardware and software components. In this paper, we argue that data center design should become a systematic process. First, it should be done using an in- tegrated approach that takes into account both the hard- ware and the software interdependencies, and their impact on users' expectations. Second, it should be performed in a "wind tunnel", which uses large-scale simulation to system- atically explore the impact of a data center configuration on both the users' and the service providers' requirements. We believe that this is the first step towards systematic data center design - an exciting area for future research. © 2014 VLDB Endowment.