Temp at Level 3 data centers

Fri Oct 13 16:57:16 UTC 2017

On October 12, 2017 at 19:56 jfmezei_nanog at vaxination.ca (Jean-Francois Mezei) wrote:
 > back in the arly 1990s, Tandem had a computer called "Cyclone". (these
 > were mission critical, fault tolerant machines).

ok old fart stories...tho maybe current.

IBM's big mainframes would repeat calculations as a way to detect
hardware errors.

Above a certain temperature they would do more repeating.

If there was any disagreement it would be reported and they had some
complex statistical formula to determine how many repetitions to try
next and what to accept.

I assume this was analogous to the various time sync game theoretic
formulas to decide which time reference to believe when they
conflict. It's not as simple as majority vote, the majority could be
wrong (e.g., same stuck bit.)

So, at least as it was explained to me, as it got warmer (e.g., A/C
failure) the machine would get slower and slower, potentially to a
crawl.

And there was no doubt a point at which it'd just shut itself off, but
before it got there. Since many mainframes were mission critical they
were trying to avoid that.

That was the kind of thing which made multi-million dollar mainframes
cost multi-millions of dollars.

Also, the IBM 3090 at least, was cooled via helium-filled pipes kind
of like today's liquid cooled systems. It was full of plumbing. If you
opened it up some chips were right on copper junction boxes (maybe
they were just sensors but it looked cool.)

There was always something amusing back then when an IBM service
person would show up with one of those typical gas tanks on wheels,
like one uses for welding, to top off your mainframe.

-- 
        -Barry Shein

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