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From: woolsey@nsc.UUCP
Newsgroups: comp.misc
Subject: Re: IBM mainframe for sale
Message-ID: <4673@nsc.nsc.com>
Date: Thu, 1-Oct-87 19:03:52 EDT
Article-I.D.: nsc.4673
Posted: Thu Oct  1 19:03:52 1987
Date-Received: Sat, 3-Oct-87 03:02:40 EDT
References: <4WALT@MAINE> <177200006@uxc.cso.uiuc.edu> <14944@watmath.waterloo.edu>
Reply-To: woolsey@nsc.UUCP (Jeff Woolsey)
Organization: National Semiconductor, Sunnyvale
Lines: 57

In article <14944@watmath.waterloo.edu> ccplumb@watmath.waterloo.edu (Colin Plumb) writes:
>For those of us making do with VAXen and things, what does a cray
>require?  I know it has its own heavy-duty cooling (that bench-thing
>around it), 

No, those are power supplies, one for each column.  Each power supply
puts out something on the order of 300 Amps.

>so it should be able to cope with a reasonable temperature
>range, and it would seem odd if it didn't take reasonably standard
>voltages - even if you need to run a new feeder cable in to supply the
>hundreds of amps a cray draws.
>
>So, except for the fact that "wall current" usually passes through a 15
>or 20-amp fuse on its way to the computer, why doesn't a cray fit this
>description?

Cray power is 400Hz, for one thing.  This means a motor-generator, and
you usually don't want those things where anyone can hear them, which
means a separate room for them.

Crays come with a large power/temperature monitoring and control box,
about the size of two refrigerators.  It's supposed to shut the machine
down if the temperature in any column goes outside preset limits,
something like 82? degrees.  One of these temperature sensors failed on
SN12 before we (my former employer) got the machine, and it almost
melted the solder on the boards as the temperature rose.

Cray cooling uses water or freon (I forget which) pumped through the
aluminum columns.  This fluid then goes through a fairly large heat
exchanger.  A better name for it is cooling towers.  These things are
fairly massive as well, and the one I dealt with went next to the MG
building.

Not to mention that Cray CPU's are heavy.  They consist of eight or
twelve aluminum columns containing 144 boards each.  Each board pair
shares a copper plate.  The power supplies aren't massless, either.  We
had to reinforce the raised floor where the machine was going to be.
When they wheeled it in they used fairly thick rigid metal plates to
spread the weight over that portion of the floor between the door and
the CPU location.

There's rather a lot of plumbing running under the floor between the
CPU and the cooling towers, too.

All of the above site preparation took a couple of months, I think.

SN12 has since been retired.  Its gutted hull sits in the lobby of
the Minnesota Supercomputer Center.

The above applies only to Cray-1s and Cray X/MPs.  Cray-2s are
a different aquarium.
-- 
LERMINATING PREVIOUS SESSION.  PQEASE RETRY.

Jeff Woolsey	National Semiconductor Corporation
...!nsc!woolsey -or- woolsey@nsc.COM -or- woolsey@umn-cs.ARPA