[gmx-developers] Install both MPI and non-MPI GROMACS in a single location?

[Eric Irrgang]

Thank you, Gilles.

I realized after I sent my last message that there are _potential_ conflicts for multiple modules. GROMACS is aware of or sensitive to several environment variables that could unexpectedly diverge with multiple GROMACS modules loaded for different environments. The most obvious are those in the GMXRC.

In general, I don't think this should be a problem, as long as the multiple modules are the same GROMACS release.

Someone please let me know if I'm overlooking something.

If there is a conflict with using different build configurations of GROMACS from different installation directories, we should probably try to resolve that, or at least clarify it in the documentation. I think we have traditionally preferred to decouple GROMACS installation robustness from local conventions regarding installation directories.

Best,
M. Eric Irrgang

> On May 8, 2021, at 6:43 AM, gilles at rist.or.jp wrote:
> 
> Thanks Erik,
> 
>> Can you clarify the use case? Under what circumstance would it be 
> necessary to switch between MPI and non-MPI builds in the middle of a 
> script?
> 
> Some users, probably an old habit, do the pre/post processing with gmx 
> and the computation with gmx_mpi
> 
>> If both builds are needed, why not make two separate packages or 
> modules and load both?
> 
> I was afraid spack and/or module would not accept loading two modules (
> conflict because of the same app),
> but it is not the case. Also, since the Spack community did not like 
> that idea (https://github.com/spack/spack/pull/23489) , I will drop it 
> and instead suggest users to load two modules!
> 
> Cheers,
> 
> Gilles
> 
> 
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