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Dear Dr. Stantz, > To: "'address@hidden'" <address@hidden> > From: "Stantz, Keith M" <address@hidden> > Subject: mpi and netCDF > Organization: UCAR/Unidata > Keywords: 200107241456.f6OEuZ111199 The above message contained the following: > I appear to be having problems integrating netCDF calls within > MPI routines (LAM-MPI). Briefly, a routine extracts sections > of data from a netCDF file and passes this information to a > variety of Linux PCs over a LAN. Results are gathered, combined, > and written to a file using netCDF routines. However, after > creating and defining the first dimension successfully, the second > call to nc_def_dim crashes (either a segment error within MPI, > or a core dump if I try this after executing an MPI_Finalize). > Are you aware of any protocols that should be followed when > integrating MPI and netCDF? Any suggestions or comments > would be helpful. With the possible exception of the Cray T3E, the current netCDF library does not support concurrent operation. In particular, the netCDF library is not thread-safe. If you want multiple, asynchronous access to a netCDF file, then you must centralize and synchronize access to the file using some mechanism external to the netCDF library. Such a mechanism is non-trivial, system-dependent, and (regretably) beyond our scope. A search of the the netCDF support-email archive using "MPI" found several emails. You might try contacting the original authors. The support email archive is available off the netCDF home page at http://www.unidata.ucar.edu/packages/netcdf/index.html You might also try posting a message to the netCDF user's mailing-list. > Thanks, > Keith Stantz > > Keith M. Stantz, Ph.D > Radiology Department > Indiana University > 541 Clinical Drive, Rm 157 > Indianapolis, IN 46202 > phone: (317) 274-0285 > fax: (317) 274-4074 Regards, Steve Emmerson <http://www.unidata.ucar.edu>