There is a saying “what you can’t measure, you can’t manage”.
When it comes to the data center facility, the Green Grid recommended using PUE (Power Usage Effectiveness) as a metric to measure data center efficiency. PUE is quite widely adopted in the industry today. It was intended (and still is) to be a simple metric for data centers that is easy to understand and use, that enables DC operators and IT administrators to quickly estimate the energy efficiency of their data centers, compare the results against other data centers, and determine if any energy efficiency improvements can be made or if there are potential problems. The PUE metric – which is the ratio of a facility’s total power to the power being drawn by IT equipment – requires complete knowledge and understanding of each component in the data center and its power consumption.
However, if you would analyze the ratio carefully, you realize a catch. “Power being drawn by IT equipment” – this is a variable number. IT equipment’s power consumption varies from time to time, depending on their utilization. For example, a server with 10% utilization will consume less power than a server utilized at 90% level.
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The picture on the left is an example of a data center on slab floor (this is Sun’s Santa Clara data center). The theory behind cooling such a facility is to bring the cooling closer to the heat source and deliver it horizontally (row-based) or vertically (rack-based), instead of distributing over the sub-floor.
