[Beowulf] using extend-reach IB?

richard.walsh at comcast.net richard.walsh at comcast.net
Thu Oct 11 07:20:39 PDT 2007

-------------- Original message -------------- 
From: Mark Hahn <hahn at mcmaster.ca> 

> > I can say a few words about optical active cable (OAC) choices. The 
> > current in production choice is from Intel, their Connects Cable. This is 
> are they shipping? I checked their website a couple weeks ago 
> and they were talking 1q08 availability. 
You must not have looked thoroughly enough ... ;-) ... and you tend to be very thorough, but it was after regular business hours.  Intel is selling them directly from there webstore and they offer a couple of other vendors.  That is where I got the pricing.

> > speeds out to100m. A 25m cable is going to run you about $300 (US). Power 
> similar to Gore's one (which is copper I think). 
Mmm ... their website specs them out only to 25m (with asterisk) and that is a cable with a .9cm diameter! I wonder what the bend radius is on that? Even their photo of the cable looks like a cobra ... ;-) ... might be OK if you only need one I guess.  Did not see the pricing, but if it is the same as Intel's fiber why buy the snake? The claimed power draw is lower than I expected though ... anyone actually tested/used this cable?

> > Rumor has it that is is already in at least one HPC vendors interconnect 
> > technology. 
> what does that mean? are there HPC vendors who don't just sell you anything, 
> including their sister, for a large enough customer? ;) 
What I meant is that it is part of some currently being installed high performance IB interconnects.  I think this is somewhat validating, but ...

> to me, I don't think this market is all that huge - there just aren't lots 
> of clusters with that kind of diameter, which means that long IB will be 
> a useful tool for adding a few uplinks/etc across a machineroom or 
> around the corner... 
It is a larger system product for now, but as bandwidth demands go up on smaller systems it won't be the length limitations that kill copper, but weight, diameter, added power draw, BERs, and equalizing total links costs.

> > PS There some very good white papers and studies on both the Intel and 
> >Luxtera web sites. 
> thanks, but whitepapers can't address the main (only) interesting issue: 
> whether it becomes mass-market-cheap... 

Intel's cable has been tested is for sale today like I said.  If only need a few for one long haul application, then I am not sure you need to wait around for mass market cheap.  Hey, the Canadian dollar is at an all time high ain't it?
Take care,
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