Temp at Level 3 data centers

Roy r.engehausen at gmail.com
Fri Oct 13 20:24:49 CST 2017

> 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.

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