[gmx-users] Beware of your interconnect hardware

[Mark Abraham]

Jason O'Young wrote:
> Hey All,
> 
> Not too long ago I posted about my problems with processes freezing  
> (just to refresh, I am running two dual-core nodes for a total of  four 
> processes).
> 
> I managed to remedy the problem by removing the Dell PowerConnect  2708 
> Gigabit switch and replacing it with a simple crossover cable.  Ever 
> since then, the system has been running rock solid.
> 
> Are there actually issues with switch hardware with Gromacs? I used  to 
> think that these things were pretty much fool proof. I spent about  a 
> month trying to fix what I perceived as a Linux issue.

Please be careful to differentiate a switch hardware problem from a 
Linux OS problem from an MPI problem from a GROMACS problem. The 
observation of processes freezing could be caused by a failure of any of 
those systems, and it is unfair to blame GROMACS for problems at a 
hardware level...

Your question above is a bit like someone on a motoring mailing list 
asking whether Mercedes-Benz cars have a problem with tires because you 
keep skidding off the road in your Merc. The problem could be with your 
technique as the driver, the road conditions, the speed you're driving 
at, the tires, or various bits of the car.

Mark