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Subject: Re: [OMPI users] Problem running an mpi applicatio​n on nodes with more than one interface
From: Jeff Squyres (jsquyres_at_[hidden])
Date: 2012-02-17 11:20:33

Did you have both of the ethernet ports on the same subnet, or were they on different subnets?

On Feb 17, 2012, at 5:36 AM, Richard Bardwell wrote:

> I had exactly the same problem.
> Trying to run mpi between 2 separate machines, with each machine having
> 2 ethernet ports, causes really weird behaviour on the most basic code.
> I had to disable one of the ethernet ports on each of the machines
> and it worked just fine after that. No idea why though !
> ----- Original Message -----
> From: Jingcha Joba
> To: users_at_[hidden]
> Sent: Thursday, February 16, 2012 8:43 PM
> Subject: [OMPI users] Problem running an mpi applicatio​n on nodes with more than one interface
> Hello Everyone,
> This is my 1st post in open-mpi forum.
> I am trying to run a simple program which does Sendrecv between two nodes having 2 interface cards on each of two nodes.
> Both the nodes are running RHEL6, with open-mpi 1.4.4 on a 8 core Xeon processor.
> What I noticed was that when using two or more interface on both the nodes, the mpi "hangs" attempting to connect.
> These details might help,
> Node 1 - Denver has a single port "A" card (eth21 - 25.192.xx.xx - which I use to ssh to that machine), and a double port "B" card (eth23 - & eth24 -
> Node 2 - Chicago also the same single port A card (eth19 - 25.192.xx.xx - again uses for ssh) and a double port B card ( eth29 - &eth30 -
> My /etc/host looks like
> 25.192.xx.xx denver
> denver
> denver
> 25.192.xx.xx chicago
> chicago
> chicago
> ...
> ...
> ...
> This is how I run,
> mpirun --hostfile host1 --mca btl tcp,sm,self --mca btl_tcp_if_exclude eth21,eth19,lo,virbr0 --mca btl_base_verbose 30 -np 4 ./Sendrecv
> I get bunch of things from both chicago and denver, which says its has found components like tcp, sm, self and stuffs, and then hangs at
> [] btl: tcp: attempting to connect() to address on port 4
> [] btl: tcp: attempting to connect() to address on port 4
> However, if I run the same program by excluding eth29 or eth30, then it works fine. Something like this:
> mpirun --hostfile host1 --mca btl tcp,sm,self --mca btl_tcp_if_exclude eth21,eth19,eth29,lo,virbr0 --mca btl_base_verbose 30 -np 4 ./Sendrecv
> My hostfile looks like this
> [sshuser_at_denver Sendrecv]$ cat host1
> denver slots=2
> chicago slots=2
> I am not sure if I have to provide somethbing else. Please if I have to, please feel to ask me..
> thanks,
> --
> Joba
> _______________________________________________
> users mailing list
> users_at_[hidden]
> _______________________________________________
> users mailing list
> users_at_[hidden]

Jeff Squyres
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