Good IBM doc on cpufreq

Previous posts have talked about power management in Linux, including information about the cpufreq module. IBM has published a good document explaining many aspects of how to use the cpufreq module. This document is worth a look.

Cisco & Sun Servers Spar for Best Humidity Support

One of the clear trends in data centers is to improve data center efficiency by making greater use of HVAC economizer modes. For air-side (dry-side or outside air) economizers, one of the keys to broad adoption is to be able to use outside air across as broad a relative humidity (RH) range as possible.

Among the major blade vendors, Cisco appeared to have taken the lead by offering support for the broadest operating humidity range, but Sun appears to have matched Cisco recently:

• Cisco's Unified Computing System blades support 5 to 93% RH
• Sun's Sun Fire X2270 blades support "up to" 93% RH
• HP's c-Class BL260 G5 blades support 10 to 85% RH
• IBM's BladeCenter HS22 blades support 8 to 80% RH
• Dell's PowerEdge M600 blades support 8 to 80% RH

(All humidity ranges are non-condensing. All data is from vendor web sites as of 9/3/09).

Ever-widening ranges for supported humidity make the use of dry-side economizers more feasible. If vendors were able to support 0-100% relative humidity, data center operators wouldn't need to worry about humidifcation/de-humidification controls. Eliminating such controls and systems could lower capital costs, reduce operating costs, lower the carbon footprint of facilities, and lower their water footprint as well.

--kb