Plan now, before you reach capacity

As much as a data center is about now: how it is functioning, how reliable it is, future capacity is always in the mind of a data center manager.
Fundamentally, to simplify things, a data center manager needs to worry about three essential parameters : space, cooling and power. These parameters constrain the growth of a data center. While the domain owners are constantly thinking about new computing power to enable new solutions, the facilities staff will worry about how to fulfill additional computing without crossing the physical limits on space, power and cooling.

What is the state of data center now?

This is where DCIM capacity planning tools help immensely. To predict what is needed in future, the manager needs at his/her disposal : 1) current state of affairs 2) past trend.
Current state of affairs should give him an accurate picture of the following:
1) Space – how much usable floor space is free? When new equipment is wheeled in, there should be floor space to accommodate those. How much space is left in each rack? As new computing power is added, they must be hosted in free slots in a rack with sufficient spare power. Hence, it is mandatory to know the spare capacity in each rack.
2) Power – Current power consumption is an essential element to keep track of. The data center manager must know what is the limit on max power and how much room the data center has as far as power is concerned. Also, it is not sufficient to be below threshold on max power. Each and every equipment must be able to handle the power capacity needed from it. If the PDU supplying power to few of the racks is maxed out, then either some racks need to be moved to a different PDU or that PDU must be changed.
3) Cooling – Current cooling capacity is another essential element to track. The data center manager must know whether current cooling capacity is able to handle the load. Are there hot spots? Is the data center over cooled thereby wasting power?

History is guide to the future

Although current state of affairs is of paramount importance, historical trend of growth can provide clues on future needs. If the data center tracks the computing growth both in terms of U-space as well as power, then it can extrapolate to project future needs. The growth of IT power will necessitate accompanying growth in power equipment such as PDUs, UPS etc. and also cooling units.
Hence, historical trend combined with accurate knowledge of power, cooling and space can provide guidance on future growth and how much capacity to add.