MPICH Discuss, So this is an odd one. Thanks to Hui Zhou from this list, I was able to build MPICH 4.0b1. I proceeded to build libraries and my application that I work on. And all seemed to compile just well. I then ran my model and...crash: Error opening file species.data -115 NetCDF: Error initializing for parallel access I did a bit of debugging and found that the crash was due to an environment variable that was set because my application mistakenly thought I was running Intel MPI (mainly because we didn't have detection for MPICH, so it defaulted to our "default" on this cluster of Intel MPI). When it sees Intel MPI, it sets: ROMIO_FSTYPE_FORCE="gpfs:" which we've found is useful when running with Intel MPI on our GPFS system. I whipped up a little netCDF reader executable that essentially does: call check( nf90_open(FILE_NAME, IOR(NF90_NOWRITE, NF90_MPIIO), comm=MPI_COMM_WORLD, info=MPI_INFO_NULL, ncid=ncid) ) and then: $ mpirun -np 2 ./simple_xy_rd_mpiio.exe OX_in(1,1:5): 7.1448361893544643E-008 1.7177123368128377E-007 2.8831971121690003E-007 3.7688394627366506E-007 4.6076729631749913E-007 OX_in(1,1:5): 7.1448361893544643E-008 1.7177123368128377E-007 2.8831971121690003E-007 3.7688394627366506E-007 4.6076729631749913E-007 *** SUCCESS reading example file species.data! *** SUCCESS reading example file species.data! $ ROMIO_FSTYPE_FORCE="gpfs:" mpirun -np 2 ./simple_xy_rd_mpiio.exe NetCDF: Error initializing for parallel access NetCDF: Error initializing for parallel access STOP Stopped STOP Stopped So, of course the "right" thing to do is not to set that. (Doctor, it hurts when I do this. So stop doing that.) But it got me wondering, is there perhaps a "better" way I should be building MPICH? Should this flag cause this sort of crash? Or does it mean I build MPICH/ROMIO incorrectly or incompletely (no GPFS support, say)? Thanks, Matt -- Matt Thompson, SSAI, Ld Scientific Programmer/Analyst NASA GSFC, Global Modeling and Assimilation Office Code 610.1, 8800 Greenbelt Rd, Greenbelt, MD 20771 Phone: 301-614-6712 Fax: 301-614-6246 http://science.gsfc.nasa.gov/sed/bio/matthew.thompson