Data center power usage will be the No. 1 infrastructure concern facing IT executives over the next three years, according to a Robert Frances Group research report. Five years ago, the average power requirement per rack was 1 to 3 kilowatts. With requirements for processor cycles, memory and storage continuing to grow, along with the density of the equipment packed into each rack, it's now common for a typical rack to require 5 to 7 kilowatts, with high-density blade server implementations hogging 24 to 30 kilowatts per rack. Couple this dramatic increase in power consumption with the rising price of electricity and it's clear why this issue is becoming increasingly critical.
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We recently surveyed 228 Network Computing readers with infrastructure responsibilities and asked how likely it is that they'll enhance their data center's cooling and power capacity during the next year. Indeed, 37 percent of those surveyed said capacity increases will happen or are likely to happen, while another 25 percent said they are studying the issue.
To address this coming crisis in data center power requirements, you must redesign your data center or build a new one. A modular and flexible design will be the key to future-proofing your investment. And you can't afford to ignore efficiency concerns, since energy costs aren't going to decrease over the next 10 years.
Hand in Glove
We're focusing here on data center power design, but any conversation about power in the data center must include cooling. One equipment rack that consumes 24 kilowatts of power (equivalent to about 30 kVA) requires six to seven tons, or about 78,000 BTUs, of cooling capacity. And that's only one part of the equation; airflow, measured in CFM (cubic feet per minute), is equally critical.
The equipment in our 24-kilowatt rack will require about 3,800 CFM of airflow to maintain operating temperatures within manufacturer specifications. The average data center is designed to deliver 300 CFM of airflow per rack, but the average perforated floor tile in a raised-floor data center can deliver a maximum of only 600 CFM to 700 CFM--assuming that the floor is high enough to permit that volume of airflow and that the space under the floor isn't significantly restricted by the tangle of power and data cables inhabiting that space--creating a double-edged design problem.
Determining the optimum height for a data center's raised floor is a matter of striking the proper balance between airflow and weight. The higher the floor, the more airflow, but the less load the floor can bear. Thirty inches is a typical height in a raised-floor data center.
