[mvapich-discuss] run executable with no IB interface

[Sayantan Sur]

Hello Steve,

> We have often run into the problem that a user tries to run a test with a
> single process on a machine that doesn't have an InfiniBand interface, but
> it fails, and the error message is not helpful to explain why it failed.
>
> The situation occurs, e.g. on a cluster with an IB interconnect, whose
> head node has no IB interface.  The user compiles their executable to use
> the IB interface, then wants to run a single-process test on the head node.
>
> It could be we're doing something wrong.
>
> Otherwise, I would recommend:
>
> 1) Improve the error messages to say explicitly that IB-configured
>    MVAPICH can't run on a machine with no IB interface.
>
> 2) If only a single process is started, that it be allowed to run.
>   

Thanks for your comments. They certainly make sense. Could you let us 
know what is the error message you get? I tried to run an executable 
after unloading IB support on a cluster node, and got this error message:

[surs at k21-oib:basic] 
/home/7/surs/projects/mvapich/release/trunk/bin/mpirun_rsh -np 1 k21 ./cpi
libibverbs: Fatal: no infiniband class devices found.
[0] No IB devices found

This is using MVAPICH-0.9.8 using the Gen2 (OpenFabrics) interface. We 
will aim to enable single process runs on nodes without IB interface in 
our upcoming release.

Thanks,
Sayantan.

-- 
http://www.cse.ohio-state.edu/~surs