That exact scenario happened to one of my former employers. We installed a server in a closet in this hallway. The hallway had no HVAC and the installation was in the winter (so the hallway was always very cold). I remember asking what we were going to do in the summer.<p>Eventually the summer came around and one morning the server was down. Fortunately there wasn't anything time-critical on the server, everything was backed up both on and off site and we got it up and running again a couple of hours.<p>It turned out that all we needed to do was cut a vent in the door and mount a box-fan to it.
We had a cooling failure in the room in our office that had the development servers (production server are in a data center).<p>It was well over 40C - the noise was incredible, sounded like the racks were trying to take off.
Not my 'server' room. Granted, its actually my laundry room, so the heat escapes to the rest of the house, even on hot days. You can see graphs here - <a href="http://www.digitemp.com" rel="nofollow">http://www.digitemp.com</a><p>If you are one of the unlucky then you should be setting up temperature monitoring and alerting before you exceed the melting point of your Pb free solder...
When our department was buying a moderately large cluster I remember being surprised by the fact that one of the considerations for the server room was that in the event of cooling failure you had to make sure there was enough time for the 1600 cores to shut down before the temperature went totally through the roof. I guess the power density of these packed installations is something not easily imaginable if you don't have experience with them...
We used to co-locate our servers with another software/services company that had a good setup in their office. On a cold winter morning our oldest server restarted and wouldn't come back up so I went over to their office. The server room was probably 120 degrees and the server was stuck on a temp warning on boot. Turned out their AC in the attic froze up.