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

[Greg Lindahl]

On Thu, Jan 15, 2009 at 04:26:00PM -0500, Lechner, David A. wrote:

> Sometimes the newer technology uses less power and is cheaper to
> operate....(anyone ever create a KW/MFLOP vs. Time curve?  has that
> really gone down? )

I'd think that you would have looked that up before you posted! I
don't have the curve, but it's falling rapidly enough that it's
obvious that an older cluster can be replaced with a mch smaller, new
cluster of equal performance for the cost of power. How old?  I don't
know, but I'd guess it's less than 6 years. And anyone who rents
machine room space probably replaces in ~ 3.

Since many clusters are funded by one-off funding sources, and often
the cluster buyer doesn't have to directly pay for power or rent,
you'll probably find that actual replacement dates don't make any
sense...  not only for academic sites, but commercial ones, too.

-- greg