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

[Andrew M.A. Cater]

On Sat, Dec 13, 2008 at 05:18:04PM +0530, arjuna wrote:
> Hello All,
> 
> Thank you for your detailed responses. Following your line of thought,
> advice and web links, it seems that it is not difficult to build a small
> cluster to get started. I explored the photos of the various clusters that
> have been posted and it seems quite straightforward.
> 
The easiest/most straightforward way, if you have PC's in mini-tower / 
tower cases.

Get some strong wood / steel shelving (English trade name Dexion for 
steel shelving.

Place your PCs four to a shelf.

Route cables etc. down the back of the shelf. Allow plenty of space for 
circulating air.

Add an Ethernet switch or two if needed.

[Andy - who has four computers at his feet connected to a cheap KVM 
(Keyboard/video/mouse) switch and one Ethernet switch.

> 
> The plan is first to simply create one using the old computers i have...This
> can be an experimental one to get going...Thereafter it would make sense to
> research the right mother boards, cooling and so on...
> 
> It seems that I am going to take the plunge next week and wire these three
> computers on a home grown rack...

See above.
> 
> A simple question though...Aluminum plates are used because aluminum is does
> not conduct electricity. Is this correct?
> 

No - for God's sake, if you don't know _this_ much, DON'T try and wire 
your own solution but leave your PCs in their cases.

Jim Lux's solution uses baking tray-size aluminium sheets in a 
commercial kitchen trolley. Air cooled - but you need to be extremely 
careful about how you mount the motherboards on standoffs / insulate 
etc. and  how you mount PSUs.

> Also for future reference, I saw a reference to dc-dc converters for power
> supply. Is it possible to use motherboards that do not guzzle electricity
> and generate a lot of heat and are yet powerful. It seems that not much more
> is needed that motherboards, CPUs, memory, harddrives and an ethernet card.
> For a low energy system, has any one explored ultra low energy consuming and
> heat generating power solutions that maybe use low wattage DC?
> 

A lot of telecoms racks are wired for 48V DC - but by the time you've 
gone from AC - 48V DC + DC voltage drop + conversion the other way for 
anything that requires AC it's massively inefficient :(

Car / lorry mobile equipment runs on 12 or 24V - but anything larger 
than a laptop usually needs a DC -> AC inverter and 110/240V AC out.

Something like the Intel Atom  dual core would work well - but it's 
limited in memory and I/O. The "Beowulf in a lunch box" used 12 Via 
mini-ITX boards - but it was designed as a fun project. 

> On Sat, Dec 13, 2008 at 8:50 AM, Mark Hahn <hahn at mcmaster.ca> wrote:
> 
> > What is 1u?
> >>
> >
> -- 
> Best regards,
> arjuna
> http://www.brahmaforces.com

Best regards,

AndyC
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