Drum vs. Core

Roger Holmes roger.holmes at microspot.co.uk
Wed Jul 4 17:54:57 CDT 2007

On 3 Jul, 2007, at 23:35, cctalk-request at classiccmp.org wrote:
> From: Pete Turnbull <pete at dunnington.plus.com>
>> Seems reasonable. I remember one day the 1900 at QMC went down and we
>> users were getting annoyed at the delay and we asked what was up, and
>> were told the air conditioning system had failed and under the raised
>> floor they had found nearly a foot of water. This was on the fifth
>> floor! Thinking about it now it's not feasible. The false floor had
>> ramps up from the normal floor at the computer room entrance, so the
>> water would have flowed out under the ramp and down the stair well  
>> and
>> lift shaft. Still, the story kept us quiet for a while.
> Our false floor is actually at normal floor level, so the subfloor  
> is of
> course about a foot lower, and I have actually seen it flood.  One  
> time
> the aircon went wrong; it's a type that dries the air and then
> re-humidifies it by passing it over a tray of warm water.  The valve
> controlling the level failed and so did the drain.  Nice.  Fortunately
> we noticed before it rose high enough to hit the electrics.

Well the QMC maths building was new enough to have been designed to  
have the computer, so yes maybe it was true.

> We had a different incident on Saturday after we had shut down all the
> power in the main machine room for safety testing.  About lunchtime,
> when the engineers had restored some of the power, we realised  
> there was
> a smell of burning -- not really what you want in your central machine
> room.  After a few panicky minutes, we realised it was the aircon.
> Normally it works hard to cool the room, but it's designed to  
> maintain a
> certain temperature.  With all the servers switched off, it was trying
> for the first time in years to heat the place up, and of course the
> heating coils were full of dust.

I get the same thing every Autumn, both in my car and with the  
Dimplex night storage radiators. With the latter, they also give off  
fumes from the epoxy resin which are quite nasty. For the first few  
years, for the first day or two there is a layer of air up to 3 feet  
from the ground when I get up in the morning which I would not want  
to breath. The cat comes upstairs but the dog suffers it when I  
forget to expect it. Almost back to topic, air conditioning systems  
are supposed to filter out dust, so if there was dust in the heating  
coils, does this means it was not working properly?

Roger Holmes.

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