It’s pretty easy to measure a system’s power consumption at varying levels of load, but how do you measure the burdens of cooling and noise?Luckily, I operate in a contained space. I can control the temperature to within a couple of degrees of a set point because even in the winter, the servers that I run continuously will heat the room to over 90 degrees unless I run the air conditioning. When it’s cool outside, running the room AC wastes less energy than opening a window and draining heat from the entire sealed structure.I can also control ambient noise. I can render the space completely silent by putting my servers to sleep while a test is underway. There is also enough fan and drive noise in here when the servers are powered up to make a realistic baseline for additive noise measurements. I measure ambient temperature with an infrared thermometer pointed at a piece of cardboard that’s out of the draft of the air conditioner. I’ll locate hot spots on the outside of the chassis; this heat is transmitted in the thin space between rack-mounted systems. I’ll measure the temperature of exhausted air by averaging the highest readings reflected from cardboard that’s swept slowly across fan and convective exhausts.Why cardboard? It doesn’t hold heat. It’s always the temperature of the air around it, or, if it’s in a draft, the air blown at it. Being a dull surface, it gets along nicely with the infrared thermometer, which gets confused by reflections.To create an example, I pointed a 1600 watt hair dryer at a piece of cardboard while measuring the heat from the cardboard with the IR thermometer. It rose quickly as the dryer heated up. At 30 seconds, it measured 158 degrees F. When I turned the dryer off, the cardboard dropped to room temperature within seconds. For measuring radiated heat from shiny metal with an infrared thermometer, a large Post-It note with the non-sticky part snipped off works well.On to noise. No doubt you’ve seen some treatment of the OSHA sound pressure level chart, but it’s not easy to make a connection between the noise level of a subway and the noise generated by a rack of servers.This chart is fun for kids. It answers the question, “how loud is loud?” However, it does a poor job of conveying the relationship between noise and health. This chart is better than most because it draws the danger line in what experts now concur is the right place. Which color marks the danger line, the level at which permanent hearing loss is likely? Yellow. If your workplace subjects you to at-the-ear noise levels above 80 dBA (A refers to a weighting scale that is patterned after human hearing), you’re at risk. That’s not a hard mark to hit when you work near powerful computers and high-capacity storage devices. Right now, my office is 55 dBA. at the moment, I’m testing running Tiger server on a Mac Pro.Mac Pro is quiet, but I must forewarn that the Xserve RAID fibre channel array will not do well. Even so, I’m dying to learn.There’s only one way to measure noise, and that’s with a gadget called a sound pressure level meter. A few grand will buy you a nice piece of lab equipment for the purpose, but $50-100 will get you a handheld box built for tweaking home theater systems. Amateur equipment cannot be relied upon for absolute measurements. If the same meter is used the same way for all measurements, then test results can be compared with each other, which is all that matters for my application.I’ll take several SPL readings: Office noise, office noise plus music, office noise plus music plus server., with the server driven to controlled levels of stress. Then I’ll break for lunch.Thanks for being patient, everybody. It’s worth doing right. Software Development