[openib-general] IB: I don't like what I'm seeing.

Wed Mar 31 19:03:17 PST 2004

>On Wed, Mar 31, 2004 at 12:58:08PM -0700, ron minnich wrote:
>>  we don't believe in HCA reliability here. It has not worked once in all
>>  the years of delivered networks. We're going to assume, unless we can see
>>  BER of 10-21 app-to-app, that the network is unreliable. So, yes, toss and
>>  start over is not inconceivable.
>>
>>  On the other hand, if we do get a perfect network, app to app, nobody's
>>  going to complain, but until we see it at scale 1024+, I am not sure we
>>  can really count on it.
>>
>>  Sorry if I upset anyone on this list with my comments -- forgot it was
>>  this open and it was early morning. But the code still worries me.
>
>This is open-source, peer review development, if nobody is getting upset
>we're not doing it right ;)
>
>This is the first mention of bit error rates I've seen in an infiniband
>discussion. Does anyone have end-to-end BER numbers for any deployed
>infiniband installations?

Quite difficult to determine. It would be nice to see actual numbers 
when they are available. The question is *IF* it is an undetected 
error, how do you know you got one, if you are not looking for them ? 
:-) There was some nice work when we were working on GSN (remember 
the predecessor to IB) on potential error rates based on the two 
CRC's that GSN used. I will try and dig it up.

>
>There is going to be a nasty tradeoff between BER and performance that I
>really don't think the vendors have thought about much yet.

But, infinitely fast with an infinitely large BER is a bad thing. :-)

>
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