high physical density cluster design -structural...

Velocet mathboy at velocet.ca
Tue Mar 6 11:49:04 PST 2001

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, and
> will be a pretty significant problem as it gets bigger), you might want to
> 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, has
> nice 90 degree connectors, etc.  There are a variety of similar products
> made from aluminum extrusions of one kind or another with longitudinal slots
> 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, not
> 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 aluminum
> tubing to make structures, etc. (and hand and safety railings...)   There
> 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 set
> screws to hold it together.  (Or you can epoxy it....).  For a given $$, the
> aluminum tubing will be much stronger and more rigid than the copper tubing.
> 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 that
> you can (gently) tip it over on it's side and not have it fall apart during
> 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 buckling,
> 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 a
> 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!

> >> >
> >> > Problem 1
> >> > """""""""
> >> > The problem is in the diagram above, the upside down board has another
> >> 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 but
> to
> >> put
> >> > a layer of grounded (to the cabinet) metal in between.  This will drive
> up
> >> the
> >> > cabinet construction costs. I'd rather avoid this if possible.
> >> >
> >> > Our original construction was going to be copper pipe and plexiglass
> >> 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 can
> be
> >> > bolted to our (cement) ceiling and floor for support.
> >> >

Ken Chase, math at velocet.ca  *  Velocet Communications Inc.  *  Toronto, CANADA 

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