pnetcdf 1.2.0 create file issue

[Jim Edwards]

This occurs on the ncsa machine bluewaters.   I am using pnetcdf1.2.0 and
pgi 11.10.0

The issue is that calling nfmpi_createfile would sometimes result in an
error:

MPI_File_open : Other I/O error , error stack:
(unknown)(): Other I/O error
126: MPI_File_open : Other I/O error , error stack:
(unknown)(): Other I/O error
  Error on create :           502          -32


The error appears to be intermittent and I could not get it to occur at all
on a small number of tasks (160) but it occurs with high frequency when
using a larger number of tasks (>=1600).    I traced the problem to the use
of nf_clobber in the mode argument, removing the nf_clobber seems to have
solved the problem and I think that create implies clobber anyway doesn't
it?    Can someone who knows what is going on under the covers enlighten me
with some understanding of this issue?   I suspect that one task is trying
to clobber the file that another has just created or something of that
nature.


-- 
Jim Edwards

CESM Software Engineering Group
National Center for Atmospheric Research
Boulder, CO
303-497-1842
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