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Subject: [OMPI users] questions about MPI-IO
From: Tom Rosmond (rosmond_at_[hidden])
Date: 2010-12-21 21:38:59

I have been experimenting with some simple fortran test programs to
write files with some of the MPI-IO functions, and have come across a
troubling issue. I use the function MPI_FILE_SET_VIEW with the 'native'
data representation and correctly write a file with MPI_FILE_WRITE_ALL.
However, if I change to the 'external32' representation, the file is
truncated, with a length that suggest that either only one process did a
write, or each process wrote to the same location. I was assuming that
changing to the 'external32' representation would only do a byteswap
similar to what some compilers options can do with conventional fortran
IO. Am I mis-interpreting the way to implement this feature?

I have attached my script/test program.

T. Rosmond