Next month is the one year anniversary of a guideline by the American Society of Heating Refrigerating and Air-Conditioning Engineers (ASHRAE) that recommend increasing (PDF document) the temperature of air entering servers and other data centre equipment. This increase of 77 degrees Fahrenheit to 80.6 degrees may not seem like a big deal, but it took a year-and-half of work to arrive at this recommendation and agreement by most of the major equipment vendors.
Cooling a data centre to 20 degrees Celsius may be going out of style.
The person who led the society's IT team on Technical Committee 9.9 was Roger Schmidt, an IBM fellow and its chief engineer for data centre energy efficiency.
It's unknown how many data centres have adopted the recommendation, or even have enough control over their environments to safely regulate air flows. Ken Brill, executive director of the Uptime Institute in Santa Fe, New Mexico, said he sees more understanding that the data centre temperatures can go up and says there has been a "very significant attitudinal change in a year," he said, but adds, that "many still don't know."
When evaluating power requirements during a data centre refresh, many organizations are too caught up with the big picture and miss the smaller factors that contribute to data centre heat output.
In an interview, Schmidt looked at the new temperature parameters, as well as some other issues involved in cooling data centres and reducing power usage.
How much heat can servers handle before they run into trouble?
The previous guidelines for inlet conditions into server and storage racks was recommended at 20 degrees Centigrade to 25 Centigrade. This is where the IT industry feels that if you run at those conditions you will have reliable equipment for long periods of time. There is an allowable limit that is much bigger, from 15 degrees Centigrade Fahrenheit to 31.6 degrees. That means that IT equipment will operate in that range, but if you run at the extremes of that range for long periods of time you may have some fails. We changed the recommended level -- the allowable levels remained the same -- to 17.7C to 27.2C. That means at the inlet of your server rack you can go to 27.2 degrees -- that's pretty warm. [The standard also sets recommendation on humidity levels as well.]
What made it possible to change the recommendation?
It took a year-and-half of all the IT manufacturers talking through this and making sure we had what we felt was some hard data behind this that would meet the new requirements.