Power requirement for Athlon-MP diskless nodes

Jim.Morton at aventis.com Jim.Morton at aventis.com
Tue Jun 26 10:13:02 PDT 2001

I am not sure about the Athlon, but I will relate a bit of sad experience.
We built a 20 node cluster using HD computers in BoomBox  2U chassis.
Each node is 2 600Mhz PIII,  2x 20G IDE,  CDrom and 512 - 1024 M ram.
We have lost 14 power supplies in the last year.   The +5 Standby power
goes out and the power supply must be replaced.   
Speaking with the folks at PC Power and Cooling,  I have decided to over-buy
the power supplies - replacing 350W with 450W models so that the thing is 
running at a lower percentage of max rated power to improve reliability.
bigger power supplies have bigger heatsinks as well as bigger transistors,
there really can be a margin of safety.

The nasty thing about power supply problems is that if they are marginal,
complete failures,   they seem non-deterministic.   There may be no set way
to make a system failure  - it just randomly crashes.  

I suppose something that I would want in my "dream"  cluster chassis  is a
connector rigged to the outside of the chassis to let me check power supply
voltages ( or the hardware on the mobo to let you read it )  I know some
have power-ok  indicators,  but do any comodity mobos have actual DVM
circuitry ?

As long as we are on the subject of dream cluster hardware,  here is what I
think I 

 A rack with 20  2U "slots"  each of which would take a hot-swappable box
for one
dual processor node.    Each box has its own power supply some externally
disk drives, an optional CDrom drive ( handy for loading 20 - 40 CD database
into an NFS connected oracle server )  and at least 100Mb ethernet - maybe
more than
one port  or optional  PCI connected other interconnect technology  (
although that makes
the slide-in hot-swap connectivity harder )     The Rack would have built in
switching,   network switch etc,   making the whole thing quite modular.
It would also 
be designed to enhance the cooling of the nodes - a whole system design
rather than 
pieces parts that fit together and almost work optimally.    The guts of
each cluster 
node should be able to take whatever type of 2U compatable mobo you want -
whatever processor and memory size are available.

What we built was 20 nodes in a rack  with a 24 port 10/100 T switch with
uplink and a 3KVA UPS.     My only regret was going with the HD systems
which were cheaper but turned out to be much less reliable than the
(at the time )  VALinux 501s.   The HDs  have very poor cooling design-  the
VA design
was much better.    It mattered.

> ----------
> From: 	Greg Lindahl[SMTP:lindahl at conservativecomputer.com]
> Sent: 	Tuesday, June 26, 2001 9:08 AM
> To: 	beowulf at beowulf.org
> Subject: 	Re: Power requirement for Athlon-MP diskless nodes
> On Tue, Jun 26, 2001 at 11:40:43AM -0400, Thomas R Boehme wrote:
> > We are currently planning to buy a new Athlon-MP cluster
> > I know AMD recommends a 460W power supply, but I am wondering if a less
> > powerful power supply (e.g. 300W) would be enough for a diskless node.
> Any
> > experiences or educated guesses?
> A typical modern drive consumes six to eight watts.
> g (my dash is busted :()
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