Back in the olden days when there really were data centers they had redundant HVAC systems so you lose a whole system and still have enough HVAC to keep the DP system going. Some even had huge storage tanks on the water chillers so you could lose all the A/C and still have time for an orderly shutdown/transfer to the backup site.
I am not sure we even have that kind of data center anymore. When I was leaving they were turning those "glass house" operations into a small room with few racks that replaced a half acre of raised floor. (most of the reason I left). Some could live in the "office" ambient air.
When the bad card has a red blinking light on it and you can hot swap in a new one without taking down the system you don't need me.
