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[netCDF #BGG-137311]: Do you have sample code to test netcdf 4 (parallel IO)?

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  • Subject: [netCDF #BGG-137311]: Do you have sample code to test netcdf 4 (parallel IO)?
  • Date: Fri, 17 Apr 2009 10:28:27 -0600
> Hi,
>
> I'm having some difficulty with my implementation that attempts to use
> netcdf4 parallel IO.
>
> Do you have sample code, especially code written in Fortran? I'm
> specifically using fortran 90.
>
> I am looking for some test code that you have used to test the parallel
> IO features.
>
> ________________________________________________________
> Annette Koontz
> Scientist
> FUNDAMENTAL & COMPUTATIONAL SCIENCE DIRECTORATE
>
> Pacific Northwest National Laboratory
> 902 Battelle Boulevard
> P.O. Box 999, MSIN k7-15
> Richland, WA  99352 USA
> Tel:  509-375-3609
> Fax: 509-375-3641
> address@hidden
> www.pnl.gov
>
>
>

Howdy Annette!

Firstly, make sure you get the 4.0.1 release (which just came out) as it has
some important changes in using the parallel I/O features from F90.

It's very simple: you use the nf90_create or nf90_open calls as usually, but
pass in your comm and info parameters as optional parameters. If you are
creating, you then make your def_var, def_dim, etc. calls, all collectively.

Data, by default, is written and read independently by each processor. So after
opening/creating the file and doing any metadata operations that you might want
to do, you just read/write normally from each process. The reads/writes will
take place with parallel I/O.

There is a test program. You must build netCDF with --enable-parallel-tests and
then, in the nf_test directory, make check will build the program
f90tst_parallel.f90.

Good luck and please let me know how the parallel I/O features work for you.

Thanks,

Ed

Ticket Details
===================
Ticket ID: BGG-137311
Department: Support netCDF
Priority: Normal
Status: Closed