[Beowulf] 2.6.11 is out; with InfiBand support

Mark Hahn hahn at physics.mcmaster.ca
Wed Mar 2 15:09:09 PST 2005

> Arima and Iwill have mobos with IB LOM (Landed on Motherboard).

given the choice between a $150 pcie IB nic and having it onboard,
I'd choose the separate card.  I know the IB salesdroids always 
say that getting onto the MB will change everything, but this 
doesn't make sense.  IB is completely different from onboard gigabit,
for instance, because there is no ubiquitous IB infrastructure
ready, waiting to be exploited.

the problem with "if you build it onboard, they will come" is also
the marginal cost.  onboard gigabit is nearly the same cost as 
onboard 100bT, very low, and you pretty much always want it.
onboard IB is noticably higher than onboard GBE, noticable in 
absolute terms, and you definitely have no possible use for it 
on many systems.

remember, most people don't even saturate GBE yet, and GBE 
ports are damned cheap.  GBE nics are free, and switch ports
are now down to $US 23/port:


fundamentally, IB is still facing most of the same problems it always has:

- requires fairly expensive, unique infrastructure
- not the greatest physical layer: it's easy to wind up with 
  literally tons of IB cables.
- not clearly superior in performance vs alternatives.
- apparently designed by people who disliked existing technique
  or were ignorant of it.
- not a drop-in replacement for alternatives.

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