There are a multitude of metrics available to analyze individual key performance indicators of data centers. In order to predict growth or set effective goals, it is important to choose the correct metric and be aware of their expressivity and potential limitations. As cloud based services and the use of ICT infrastructure are growing globally, continuous monitoring and measuring of data center facilities are becoming essential to ensure effective and efficient operations. In this work, we explore the diverse metrics that are currently available to measure numerous data center infrastructure components. We propose a taxonomy of metrics based on core data center dimensions. Based on our observations, we argue for the design of new metrics considering factors such as age, location, and data center typology (e.g., co-location center), thus assisting in the strategic data center design and operations processes.