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).
The separate box was a heat exchanger. In the "old" days, buildings
had central systems that provided chilled water. Its similar to your
house HVAC where an outside unit cools Freon and you have a heat
exchanger that cools the inside air. In the case of the water cooled
mainframe, the same chilled water was connected to the exchanger and
not directly to the computer. The water running through the computer
was a closed system.
