[Beowulf] RE: Capitalization Rates - How often should you replace a cluster? (resent - 1st sending wasn't posted ).

Robert G. Brown rgb at phy.duke.edu
Wed Jan 21 17:12:43 PST 2009

On Wed, 21 Jan 2009, Lux, James P wrote:

> Sure, it's lowball, but even if you multiply by 5 ($5/sq ft), it's still
> less than the utility costs...
> And, really, the question originally was whether in 3 years you've paid as
> much for infrastructure and utilities than you did on the box, and I think
> that it's certainly in that area.


It's just that in the colo facilities that I've seen, they charge more
by the U or by the rack than by ft^2.  Not that I have sweeping
experience in this arena -- I've priced out one commercial server center
and looked extensively at a state sponsored center in the RTP -- the
latter is quite reasonable (but partially subsidized for academic use).
They seemed considerably higher "per ft^2" if you fill a rack on a per-U
basis.  I seem to recall $50-100/month per 1U or 2U server, something
like that (including power/ac) which is commensurate with your estimate
but clearly charges more for "volume" rather than floor space per se.

Either way, you quite rapidly get to where this cost for N nodes will
pay for a single node Nx as powerful when you're paying out anywhere
from 20% to 33% of the node budget per year.  As little as two years,
more often the 3-5 discussed, and by 6 the node needs to have "free"
power and housing or it starts not being worth it period.


Robert G. Brown                            Phone(cell): 1-919-280-8443
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