high physical density cluster design -structural...

Lechner, David Lechner at drs-esg.com
Tue Mar 6 12:33:50 PST 2001

I'll throw in that there are some valid liability concerns and Underwriters
Lab issues and insurance policy issues that people building their own
hardware should think about - 
There are greater risks of electrical fires when dealing with plexiglass and
plywood casing for electrical products - esp. ones that get hot spots and PC
processors and such - 
I would hate to have to explain to a corporate or university financial
manager after-the-fact when 50 PCs in plywood or plastic cases were mounted
in a high density home-grown arrangement caught on fire or worse-yet that
fire injured someone or electricuted someone.
That bunch of UL and NEBS tests are what the insurance industry falls back
onto, and is why the products are slightly more expensive than spin-your-own
boxes.  I think that university teams in particular are given some
flexibility (in some cases not!) but since the market for cluster products
has evolved now it seems worth considering.

This also does not count the personal or project time factors involved - are
you in the hardware business or do you want to get code running - there are
qualified hardware vendors that can provide hardware to specification or in
vanilla flavor at reasonably quick turnarounds - 

Best of luck in the project though - 
Rave Lechner

-----Original Message-----
From: David Grant [mailto:davidgrant at mediaone.net]
Sent: Tuesday, March 06, 2001 3:13 PM
To: Velocet; Jim Lux; rutile at fixy.org; bcrl at kvack.org
Cc: beowulf at beowulf.org
Subject: Re: high physical density cluster design -structural...

This has been an interesting thread, but I do have a concern about
appropriate cooling  with "homegrown" 1U chassis.  Yes, you can build a box
the will physically support the hardware in a 1U form factor.  My concern
would be long term, and not so long term heat related failures on CPU's
and/or disk drives.....

just my .02

David A. Grant,  V.P. Cluster Technologies
GSH Intelligent Integrated Systems
95 Fairmount St. Fitchburg Ma 01450
Phone 603.898.9717       Fax 603.898.9719
Email: davidg at gshiis.com      Web: www.gshiis.com
"Providing High Performance Computing Solutions for Over a Decade"
----- Original Message -----
From: "Velocet" <mathboy at velocet.ca>
To: "Jim Lux" <James.P.Lux at jpl.nasa.gov>; <rutile at fixy.org>;
<bcrl at kvack.org>
Cc: <beowulf at beowulf.org>
Sent: Tuesday, March 06, 2001 2:49 PM
Subject: Re: high physical density cluster design -structural...

> On Tue, Mar 06, 2001 at 11:23:37AM -0800, Jim Lux's all...
> > Rather than the copper pipe and fittings (which isn't very structural,
> > will be a pretty significant problem as it gets bigger), you might want
> > look at some alternatives:
> Ya, were convening with a few people who've done some work with metal
> as well as piping this week to go over a few other cheap options. The
> cluster will be 48 to 64 nodes depending on pricing of other materials,
> network switches, etc. 48 nodes will be 2 stacks of 24, and at 1U per,
> thats only 3.5' tall. So we dont need something thats bombproof,
> just sturdy.
> > 1) UniStrut (available in aluminum and in galv steel) is much stronger,
> > nice 90 degree connectors, etc.  There are a variety of similar products
> > made from aluminum extrusions of one kind or another with longitudinal
> > that make very nice rigid boxes. You assemble it with captive nuts and
> > bolts. The best thing about these products is that they are rectangular,
> > round, which makes attaching stuff much easier.
> Hmm, this stuff looks really great - and they seem to be somewhat local
> to me. :) Looks like it might not be that cheap however, even if it is
> 'cheap' for industrial applications. Wonder if I can find prices online
> somewhere here...
> > 2) Speedrail - a brand of cast aluminum fittings that works with
> > tubing to make structures, etc. (and hand and safety railings...)
> > are other brands, as well.  There are versions for 2" and 1" tubing, at
> > least.  The tubing fits into the socket on the fitting, and you tighten
> > screws to hold it together.  (Or you can epoxy it....).  For a given $$,
> > aluminum tubing will be much stronger and more rigid than the copper
> >
> >
> > As far as design guidelines go,  a 0.6 g side load, or so, would be an
> > appropriate number.  For instance, you should build it strong enough so
> > you can (gently) tip it over on it's side and not have it fall apart
> > the move.  In even a small earthquake, poorly braced sheet metal racks
> > loaded with many pounds of equipment just crumple.  Especially on less
> > expensive racking, a lot of the strength depends on the sides not
> > and once it bends even a little bit, it just caves in.
> >
> > After all, some day, you WILL have to move the rack a bit, even if only
> > few feet to let them take up the tile underneath it.
> True. I dont have a scale, but the board with CPU and ram is about 1.5 or
> 2lbs, and the power supply is 2-3lbs. That adds up with 48 or 64 odd
> boards. (Need to figure out if I am going to double up the mainboards
> per powersupply, would save alot of weight).
> Thanks for the pointers!
> /kc
> >
> > >> >
> > >> > Problem 1
> > >> > """""""""
> > >> > The problem is in the diagram above, the upside down board has
> > >> board
> > >> > .5" above it - are these two boards going to leak RF like mad and
> > >> interefere
> > >> > with eachothers' operations? I assume there's not much to do there
> > to
> > >> put
> > >> > a layer of grounded (to the cabinet) metal in between.  This will
> > up
> > >> the
> > >> > cabinet construction costs. I'd rather avoid this if possible.
> > >> >
> > >> > Our original construction was going to be copper pipe and
> > >> sheeting,
> > >> > but we're not sure that this will be viable for something that
could be
> > >> rather
> > >> > tall in our future revisions of our model. Then again, copper pipe
> > be
> > >> > bolted to our (cement) ceiling and floor for support.
> > >> >
> >
> >
> --
> Ken Chase, math at velocet.ca  *  Velocet Communications Inc.  *  Toronto,
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