Despite the relatively poor PUE score, Digital Realty's survey points to increased efforts to improve efficiency. Four out of five respondents said they take steps to keep hot exhaust air from servers mixing with cold air used for cooling, known as hot-aisle or cold-aisle containment. That was up from less than two-thirds in 2011. And 85 percent use some type of data center infrastructure management software, an emerging class of products that can be used to improve efficiency.
Other findings include:
-- Nearly all respondents, 98 percent, said they plan to expand their data centers in 2013 or 2014, the highest percentage in the seven years Digital Realty has sponsored the survey;
-- 65 percent would prefer to locate a new or expanded data center in New York City;
-- Among international locations, London (39 percent), Hong Kong (34 percent) and Tokyo (27 percent) were mentioned most often;
-- 66 percent have built or acquired a new data center in the past two years;
-- A quarter of respondents reported operating six or more data centers, not including "IT closets" in branch offices;
-- The average power density is 8.5 kW per rack, and the average IT load is 2.6 mW, both up from last year.
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