[Beowulf] Newbie Question: Racks versus boxes and good rack solutions for commodity hardware

Lux, James P james.p.lux at jpl.nasa.gov
Fri Dec 12 08:58:50 PST 2008


        From: beowulf-bounces at beowulf.org [mailto:beowulf-bounces at beowulf.org] On Behalf Of arjuna
        Sent: Thursday, December 11, 2008 2:05 AM
        To: beowulf at beowulf.org
        Subject: Re: [Beowulf] Newbie Question: Racks versus boxes and good rack solutions for commodity hardware

        I am in NewDelhi India. However I would prefer to put the cluster together myself, because

        1) I am a good python programmer and like programming and playing with computers
        2) I will be using the cluster for animation (art + computers) and may have to bend it and tinker with it...therefore it makes sense for me to know it inside out.
        3) If I set it up then I can grow it, and i envision it growing, outsourcing the whole thing would be expensive
        4) I have been using linux for several years and am comfortable in the environment
        5) I have a bunch of old computers lying about which are not so old and run basic versions of linux fast.

All decent reasons to put together a cluster.

>       What is 1u?

Standard rack mount systems (with 19" wide RETMA/EIA panels) have certain vertical heights for each component (as well as standard hole patterns).  1 U = 1 Unit = 1 7/8"  (4U = 7", 2U= 3.5")

As a practical matter, 1 U high systems are quite tight inside, and tough to cool, because the fans can only be an inch or so high (maybe 40mm) and to move any amount of air, they have to spin fast. Fast small fan = low efficiency, lots of noise..

>What is a blade system?

Where there's a "card cage"  into which one slides cards (or "blades") which are a whole PC.  They all share a common power supply and they're denser because you don't have extra sheetmetal between PCs.

OTOH, denser means more heat in a small volume, which aggravates the cooling problem.
Why "blades".. -> it sounds cooler (no, really... It's because of marketing.  Cards in a card cage is so 1950s.. Why, PDP-8s and IBM 1401s use cards in a card cage..)

>I would be putting it in a room with air conditioning.

There's "air conditioning" and "AIR CONDITIONING".. Throw a few kilowatts worth of computers in a room, and you'll find out which one you have.

>At this time I am trying to figure out the racks. Am meeting the hardware guy on Saturday and we were thinking of opening up the PCS i have lying around and taking measurements of how the mother boards fit into the cases,with the intention of creating a rack from scratch. Any ideas of what goes into a good rack in terms of size and matieral (assuming it has to be insulated)

My favorite "field expedient" scheme is to use half or full size aluminum baking sheets with raised edges (aka jelly roll pans or sheet pans) and double stick foam tape. You can slide them into a standard baker's rack.  All readily available or improvised, although I'd look for the real rack (they're cheap and sturdy).  The pans can just be sheets of aluminum sheared to size, if you like. Search the archives of the list for some website addresses of kitchen supply places where you can see a picture of this kind of thing.  There is CERTAINLY some local source where you live for this stuff (ask at any commercial kitchen or bakery)

> Also again, what might be some upto date books on the subject and any experiences regarding the actual creation of the rack and the physical hardware.

Catalogs are your friend, as far as packaging goes.

>I am starting with 3 nodes to be expanded to n nodes....The 3 nodes will allow me to keep complexity down while learning and then i can expand to n nodes once i have it down to increase speed.

Good luck.. At 3 nodes, you can just throw the PCs under the table and hook em up with a ethernet switch.

But, if you find a pallet load of surplus PCs, and want to repackage them a bit more densely, then the cookie sheet approach is easy.

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