Cabling and other hardware¶

Like a number of others this is for historical purposes, but yes, I really did run a real business with a “server room” that was cooled using a aircon unit we just hauled in from B&Q.

Power, and Cooling¶

At some point a small company will move from having a few laptops, to having a server.[#]_ And at some point after that they get another one, and an IT manager, and soon they have to think hardware.

A Pentium4 CPU can hit 90C, and stay there under heavy load. The fans and other noise are designed to throw that heat away from the CPU. One of the most common causes of computer failure is overheating in summer. [1]

So in essence we are running an office full of bar heaters.

How do I cool this all down ?¶

Its all down to Watts. 1 watt is a rate of power consumption equal to 1 joule per second

on average a single server will consume 60-120W (yes that is a big varience, but dual cores and load all make a difference. Measure it using a kill-a-watt meter for ease) .

so, 120 W = 120*3.41 = 409 BTU for a single server So, 15 servers, all running at once will pump out about 9000 BTU 9000 BTU is the bottom end rating for a DIY air conditioner. Do you see where we are going?

So if I have a 6000 BTU rated air conditioner I can in theory have 30 servers on at full blast and the temperature will stay the same.

[1]	Admittedly that point gets further off as years pass - web

based services really do offer a small business a real benefit if they are willing to risk hosting. [Ha - can you see my bold prediction of the cloud-computing era. Well at least I saw it’s benefits :-)]

[2]	Curiously tropical and desert failures due to heat seem to be

less commonly reported. My assumption is that in the UK most of the year it is cold enough to get away with no (or insufficient) dedicated cooling. When summer hits, the servers pay the price. In a hot climate, that is an ever present threat and is factored in from the start.