James Hamilton pointed to an Intel Brief titled
Reducing Data Center Cost with an Air Economizer
that cost conscious folks will want to look at. The concept: let’s take vendors at their specs for temperature ranges and use free outside air to cool a data center.

Google reported that temperatures below 40C (104F) did not affect drive life. So the Intel researchers – Don Atwood, an Intel regional data center manager and John G. Miner, a senior systems engineer – conducted a proof of concept test using 900 servers in a 1,000 sq. ft. trailer.

Each space housed 8 racks with a total of 448 blades and a power density over 200 watts per sq. ft. Dividing the trailer in half, they air-conditioned one half and for the other half they

. . . used essentially the same air-conditioning equipment, but with modifications that enabled it to operate as an economizer by expelling hot air to the outdoors and drawing in 100 percent outside air for cooling.

The economizer used outside air and only kicked in to heat or cool when the air temp was less than 65F or more than 90F. They didn’t control for humidity – not a problem in their temperate desert location – and only used a standard household air filter to remove large particles.

Their cheap air conditioner let temperature vary from 64F to over 92F. Humidity varied from 90% to 4%. And the servers got covered in dust.

The air-conditioned space had a server failure rate of 2.45% and the naked space just 4.46% – and the former was lower than the main data center rate. The authors called this difference “minimal” and not knowing the statistics I have to take them at their word.

The power savings are impressive:

Based on our 74 percent measured decrease in power consumption when using the economizer during the PoC, and assuming that we could rely on the economizer 91 percent of the year, we could potentially save approximately 67 percent of the total power used annually for cooling . . . .

. . . In a larger 10-MW data center, the estimated annual cost reduction would be approximately USD 2.87 million.

Plus think of the HVAC gear you wouldn’t need to buy or maintain.

The StorageMojo take
IT gear has grown more rugged over the years. Enterprise disks used to have a 25,000 hour MTBF – and vendors bragged on it.

The combination of plunging hardware prices, improved availability through software and increasing energy prices mean it is time to examine the assumptions of 40 years ago. Even if free air cooling increased server mortality, $3 million will buy a lot of servers.

Intel will continue testing this concept with a larger PoC. Kudos to Don, John and Intel for this ground-breaking work.

Update: I misinterpreted the server failure rates and corrected the data and conclusion above. Thanks to alert reader Paul for spotting the error. End update.

Courteous comments welcome, of course.