I will answer this before Clay does: Computers are LOUSY thermometers!! Even computers like the (very expensive) SuperDome. You can determine if a temperature warning has occurred (apx. 85-90 deg F) or an emergency has occurred (95 to 105 deg F) at which point the SuperDome shuts itself off. Wonderful. The computer protected itself but the disk arrays, tape drives, network appliances and other servers, PCs, printers, etc will meltdown. Oh, they won't always melt, their electronics is permanently damaged so they seldom work right if at all.
DO NOT relegate temperature monitoring to equipment that was never designed for this job. There are a several companies that provide not only accurate and multipoint temperature monitoring but also check on water on the floor (ALWAYS a problem in computer rooms with poor air conditioning) and humidity, and can connect into central alarm systems (email is far too unreliable for a problem that can destroy millions of dollars of equpment).
These alarm systems are monitored by the same people that watch for fire and burglary, etc. The advantage is that a live body will keep calling until someone is located to take care of the problem. You can be sure heads will roll if there are 10 emails warning about airconditioning failure in the sysadmins mailbox on Sunday evening that were not read until Monday morning. Even pager notification is far too unreliable -- no verification of receipt or acknowledgement that action is taking place.
And even with a solid environmental monitoring system, you still need a thermostatic circuit breaker that removes all power once the room reaches 100 deg F. Even with 24x7 it may be too late to start powering things down, especially if the airconditioning cannot be fixed in 10 minutes.
By the way, a typical data center that loses all airconditioning will rise in temperature to 100 degrees in less than 10 minutes, 140 degrees in less than 20. At 140 deg F, you call the insurance company to cover your loss.
Bill Hassell, sysadmin
