Datacenter temperature has been ramping up rapidly over the last 5 years. In fact, leading operators have been pushing temperatures up so quickly that the American Society of Heating, Refrigeration, and Air-Conditioning recommendations have become a become trailing indicator of what is being done rather than current guidance. ASHRAE responded in January of 2009 by raising the recommended limit from 77F to 80.6F (HVAC Group Says Datacenters Can be Warmer). This was a good move but many of us felt it was late and not nearly a big enough increment. Earlier this month, ASHRAE announced they are again planning to take action and raise the recommended limit further but haven’t yet announced by how much (ASHRAE: Data Centers Can be Even Warmer).
Many datacenters are operating reliably well in excess even the newest ASHRAE recommended temp of 81F. For example, back in 2009 Microsoft announced they were operating at least one facility without chillers at 95F server inlet temperatures.
As a measure of datacenter efficiency, we often use Power Usage Effectiveness. That’s the ratio of the power that arrives at the facility divided by the power actually delivered to the IT equipment (servers, storage, and networking). Clearly PUE says nothing about the efficiency of servers which is even more important but, just focusing on facility efficiency, we see that mechanical systems are the largest single power efficiency overhead in the datacenter.
More of the Perspectives post from James Hamilton