On 2017-10-13 14:10, Roy wrote: > > > The IBM 308x and 309x series mainframes were water cooled.
The bank I worked for had just installed one. A big change were noise levels, the thing was really quiet. But servicing now required a plumber too. (there was a separate cabinet for the water pumps as I recall.) But in all cases, the issue is how long you can survive when your "heat dump" is not available. If nobody is removing heat from your water loop it will eventually fail too. In the end, it is a lot easier to provide redundancy for HVAC in one large room than splitting the DC into small suites that each have their 1 unit. Redundancy there would require 2 units per suite. And the problem with having AC units that are capable of twice the load (in case other one fails) is that it increases the on-off cycles and thus reduces lifetime (increases likelyhood of failure).
