Power Usage Effectiveness (PUE) is a ratio of the total amount of power used by a data center to the power delivered to IT equipment. The PUE metric was developed by The Green Grid to measure the overall energy efficiency of data centers, and it has been one of the most popular data center KPIs since its introduction in 2007.

Data center capacity refers to key data center resources (i.e., power, space, cooling, and power/network port connections) that are available to meet the requirements of current and future IT demand. Accurately planning and managing data center capacity is essential for maintaining uptime and increasing efficiency. Failure to do so can be very expensive and detrimental to the business.