Computer Shelves

[Robert G. Brown]

On Thu, 15 Feb 2001, Leonardo Magallon wrote:

> Greetings Beowulfers,
>
> We are wondering about what shelves we should get for the extra 32 Duals we are adding to
> our  already existing cluster.
> I have been looking at all the shelves that are sold by companies that are specific for
> computer systems.  These include places  for input/ouput peripherals and the like.  Since a
> cluster does not use these peripherals on a per-computer basis, my question is: What would be
> the difference between getting those metal shelves or getting the plastic regular tool
> shelves one can get at SAMS or PriceClubs?
> I won't be bolting them to anything to share a common ground (if at least one is needed.)
> If I need metal shelves, then is grounding the shelf to some ground rod the recommended
> method.  If I need a plastic shelf, is there any static electricity problems?
>
> I am sure that there is a reason behind using metal shelves for computer systems because all
> shelves I've seen in computer labs are made of metal.

I got a very awesome heavy duty steel shelf unit from Home Depot for my
home beowulf (Eden).  I highly recommend it for any mini or mid tower
style cluster.  See photo:

   http://www.phy.duke.edu/~rgb/Eden_1.gif

The shelf supports are seriously thick steel (1-2mm -- strong and
heavy), unit weight limit a ton or two, the shelves are half inch
particle board (you could undoubtedly cut 3/4" plywood to replace if you
plan to tap dance on them or store engine blocks on them).  Easy to
screw into or drill wiring holes in a la carte.

I took 2x2's and cut them to fit across the bottom side supports,
screwed them in through the shelf holes there, and mounted the whole
thing on casters.  I can now roll my beowulf around at home.

The arrangement pictured holds three units on the bottom, network
switch, KVM switch and "miscellaneous crap" on the second shelf, and (in
my home arrangement) a laser printer and scanner/color printer on top.
A more conventional node-only arrangement would easily hold four
minitowers per shelf, and one could arrange for four comfortable shelves
per unit (or 16 minitowers per unit, more if you use the really small
micro cases).  Only half of the whole shelf unit is shown, BTW -- the
other half I didn't need (yet) and is in the garage.  Assembled together
the unit stands about 7" tall, or can be set up as a pair of 3.5 foot
units like the one shown, one three shelf and one two.  The open design
lets me easily get at the business end of the systems (whichever that
might be on a given day and the rollers let me easily access any point
even in a relatively crowded home office.

Total cost:  $50.  Plus $10 for the casters, if you want to emulate
this as well.  I've spent literally 10x as much for commercial systems
shelving and it is a waste of money.  Although this figure doesn't show
it, the little shelf holes are just perfect for tying off cables.

As for grounding, if worried just screw your power supply strips onto
the sides of the steel shelves (or otherwise ground them to the steel).
I don't bother -- the shelves are big (large capacitance) and have sharp
corners and won't build up much charge anyway.  Besides, the systems
themselves sit on insulating particle board and are all grounded.  If
your environment stimulates ground loops or is very static prone, just
wire the shelf units together and hook them to a >>single<< cold ground.

Can't recall the name of the shelf manufacturer but once you've seen the
picture you should be able to find it (or an equivalent) pretty easily.
Its in the box labelled "heavy duty steel shelving" that weighs about
eighty pounds;-)

   rgb

-- 
Robert G. Brown	                       http://www.phy.duke.edu/~rgb/
Duke University Dept. of Physics, Box 90305
Durham, N.C. 27708-0305
Phone: 1-919-660-2567  Fax: 919-660-2525     email:rgb at phy.duke.edu