Racks vs. pile of PCs

Josip Loncaric josip at icase.edu
Wed Aug 14 10:59:24 PDT 2002

David Mathog wrote:
> Racks better than piles:
> 1.  Space efficiency.
> 2.  Aesthetics (racks look cool)

I'd add another item to this list:  Racks are a large assembled unit,
much quicker to move and set up somewhere else than shelves and lots of
small boxes plus shelves and their numerous wires.

Our institute moves from building to building every couple of years. 
Our neatly wired cluster has to be taken apart then reassembled; this
reason alone justifies at least a few percent extra in the price of a
rack.  If, in addition, we had space problems (which we do not) than
racks would win; for now we're using mass produced parts.

Regarding reliability: power supply fans indeed fail after about 3 years
(we just replaced 4 units).  Initially, out-of-spec NICs are also
common, but once they are replaced, they rarely go bad.  Virtually all
other purely electronic parts have been OK for years.  However, we've
seen a steady stream of IDE drives needing replacement when bad blocks
become unmanagable, so much so that diskless compute nodes are starting
to look attractive.  SCSI drives are more reliable but not bulletproof
either (we just lost one that had seen 4 years of heavy use in our
server).  If local disks can be dispensed with, you'd want to build
clusters using space efficient CPU+memory units w/good network
capability (and easily replacable fans).  If this kind of minimalist
module could become an industry standard, a company capable of mass
producing them at a good price could sell quite a few...  even if they
end up costing 20% extra.


Dr. Josip Loncaric, Research Fellow               mailto:josip at icase.edu
ICASE, Mail Stop 132C           PGP key at http://www.icase.edu./~josip/
NASA Langley Research Center             mailto:j.loncaric at larc.nasa.gov
Hampton, VA 23681-2199, USA    Tel. +1 757 864-2192  Fax +1 757 864-6134

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