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Subject: Re: [OMPI users] Change In Behavior Running on Multiple Nodes
From: Ralph Castain (rhc_at_[hidden])
Date: 2013-04-17 10:44:55


Hmmm...yes, I see what you mean. Try using "-default-hostfile mpimachines" instead of -hostfiles. I think that's the problem - at least, it fixed it for me.

On Apr 17, 2013, at 7:08 AM, "Welder, Wallace T PWR" <Wallace.Welder_at_[hidden]> wrote:

> I’ve recently tried running OpenMPI v1.6.4 on multiple nodes and have noticed a change in behavior that I don’t understand. In OpenMPI version 1.4.x, 1.5.x and 1.6.1, I could run a job spanning two nodes as shown below. The procedure results in 8 processes running on the first node and 8 on the second node.
>
> mpirun –hostfile mpimachines –n 1 host.exe : -n 15 node.exe
>
>
> where the file mpimachines looks like:
>
> node1 slots=8
>
> node2 slots=8
>
> In OpenMPI v1.6.2 and v1.6.4 (haven’t tried v1.6.3) when I try to run the same way, all the processes start on node1 and none start on node2. I’ve noticed there are now runtime flags -bynode and –byslot, but I haven’t had any success with those. I’ve also tried changing the mpimachines file to look like:
>
> node1 slots=8 max-slots=8
>
> node2 slots=8 max-slots=8
>
> When I tried this, I got a runtime error saying there were not enough slots in the system to satisfy the 15 slots that were requested by the application node.exe. I think there is a hint in here about my problem, but I haven’t been able to figure out what it is yet.
>
> Can anyone let me know how the process has changed with these newer versions of OpenMPI?
>
> Thanks,
>
> Wallace
>
>
>
>
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