in all honesty is there a need really to replace the cluster. why not just add onto it?
On Mon, Jan 19, 2009 at 2:40 AM, Robert G. Brown <r...@phy.duke.edu> wrote: > On Sun, 18 Jan 2009, Greg Lindahl wrote: > > On Fri, Jan 16, 2009 at 08:10:43PM -0500, Mark Hahn wrote: >> >>> The question was raised as "When should all these servers be upgraded or >>>> replaced again?" >>>> >>> >>> 3-5 years, IMO. if you replace hardware in <3 years, you're obviously >>> burning money. >>> >> >> After factoring in rent and utilities, my replacement time is < 3 >> years. So what's obvious to you doesn't seem very obvious to me! >> > > Right. There are rules of thumb, but they are based on assumptions, and > if the assumptions aren't applicable they will lead to non-optimal > behavior. The right rule is "do the cost-benefit analysis and act > according to what it tells you". Which will, in fact, often lead to 3-5 > year replacement cycle. But additional costs along the way alter the > landscape, shifting to different replacement cycles. > > To do the computation correctly, you have to include all sorts of > marginal costs and benefits. For example, sometimes there are nonlinear > benefits to finishing work faster, which favors shorter cycles. > Sometimes there are nonlinear costs (or higher than normal linear > costs, which ALSO favors shorter cycles. > > On the other hand, if somebody else pays for the power, and you have no > source of money to buy replacement nodes, you run nodes until they die. > All the "usual" CBAs assume a constant flow of support moneys for new > nodes, and that is not always the case. > > rgb > > >> -- greg >> >> >> >> _______________________________________________ >> Beowulf mailing list, Beowulf@beowulf.org >> To change your subscription (digest mode or unsubscribe) visit >> http://www.beowulf.org/mailman/listinfo/beowulf >> >> > Robert G. Brown Phone(cell): 1-919-280-8443 > Duke University Physics Dept, Box 90305 > Durham, N.C. 27708-0305 > Web: http://www.phy.duke.edu/~rgb > Book of Lilith Website: http://www.phy.duke.edu/~rgb/Lilith/Lilith.php > Lulu Bookstore: http://stores.lulu.com/store.php?fAcctID=877977 > _______________________________________________ > Beowulf mailing list, Beowulf@beowulf.org > To change your subscription (digest mode or unsubscribe) visit > http://www.beowulf.org/mailman/listinfo/beowulf > -- Jonathan Aquilina
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