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From: Tom Lund (lund_at_[hidden])
Date: 2007-01-08 16:32:14


Rainer,
   Thank you for taking time to reply to my querry. Do I understand
correctly that external32 data representation for i/o is not
implemented? I am puzzled since the MPI-2 standard clearly indicates
the existence of external32 and has lots of words regarding how nice
this feature is for file interoperability. So do both Open MPI and
MPIch2 not adhere to the standard in this regard? If this is really the
case, how difficult is it to define a custom data representation that is
32-bit big endian on all platforms? Do you know of any documentation
that explains how to do this?
   Thanks again.

    ---Tom

Rainer Keller wrote:
> Hello Tom,
> like MPIch2, Open MPI also uses ROMIO as underlying MPI-IO implementation as
> an mca. ROMIO implements the native datarep.
>
> With best regards,
> Rainer
>
>
> On Friday 05 January 2007 20:38, lund_at_[hidden] wrote:
>
>> Hi,
>> I am attempting to use the 'external32' data representation in order
>> read and write portable data files. I believe I understand how to do
>> this, but I receive the following run-time error from the
>> mpi_file_set_view call:
>>
>> MPI_FILE_SET_VIEW (line 118): **unsupporteddatarep
>>
>> If I replace 'external32' with 'native' in the mpi_file_set_view call then
>> everything works, but the data file is written in little endian order on
>> my Opteron cluster. Just for grins I also tried 'internal' but this
>> produces the unsupporteddatarep error as well.
>>
>> Is the 'external32' data type implemented? Do I need to do something else
>> to access it? I looked in the FAQs as well as the mailing list archives
>> but I can not seem to find any threads discussing this issue. I would
>> greatly appreciate any advice.
>>
>> I have attached my sample fortran codes (explicit_write.f,
>> explicit_read.f, Makefkile) as well as the config.log, output of
>> ompi_info, and my environment variable settings. I am running Fedora Core
>> 4 with the 2.6.17-1.2142_FC4smp kernel.
>>
>> Thanks,
>>
>> ---Tom
>>
>
>

-- 
===========================================================
   Thomas S. Lund
   Sr. Research Scientist
   Colorado Research Associates, a division of
   NorthWest Research Associates
   3380 Mitchell Ln.
   Boulder, CO 80301
   (303) 415-9701 X 209 (voice)
   (303) 415-9702       (fax)
   lund_at_[hidden]
===========================================================