Clusters Vs Grids

[Mark Hahn]

> I'm having a hard time marrying the 2 concept of a cluster and a
> grid together; but I'm sure much finer brains than mine have already

"grid" is just a marketing term stemming from the fallacy that networks
are getting a lot faster/better/cheaper.  without those amazing crooks 
at worldcom, I figure grid would never have accumulated as much attention
as it has.  I don't know about you, but my wide-area networking experience
has improved by about a factor of 10 over the past 10-15 years.

network bandwidth and latency is *not* on an exponential curve,
but CPU power is.  (as is disk density - not surprising when you consider
that CPUs and disks are both *areal* devices, unlike networks.)  so we should
expect it to fall further behind, meaning that for a poorly-networked cluster
(aka grid), you'll need even looser-coupled programs than today.

YOU MUST READ THIS:
	http://www.clustercomputing.org/content/tfcc-5-1-gray.html

cycle scavenging is a wonderful thing, but it's about like having
a compost heap in your back yard, or a neighborhood aluminum
can collector ;)

> I'd appreciate that as well; "grids - hmmm - there're just the
> latest computing fad - real high performance scientists won't use
> them and grids will be just so much hype for many years to come".

my users are dramatically bifurcated into two sets: those who want
1K CPUs with 2GB/CPU and >500 MB/s, <5 us interconnect, versus those
who want 100 CPUs with 200KB apiece and 10bT.  the latter could be 
using a grid; it's a lot easier for them to grab a piece of the 
cluster pie, though.  I wonder whether that's the fate of grids 
in general: not worth the trouble of setting up, except in extreme
cases (seti at home, etc).

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