[mpich-discuss] MPI-IO issue

[Grismer, Matthew J Civ USAF AFMC AFRL/RBAT]

I am attempting to use MPI-IO to read block, structured data from a
file.  Three three-dimensional coordinate arrays are stored in the file,
one after another with Fortran ordering and in binary (not Fortran
unformatted):

header info
(((x(i,j,k),i=1,ie),j=1,je),k=1,ke)
(((y(i,j,k),i=1,ie),j=1,je),k=1,ke)
(((z(i,j,k),i=1,ie),j=1,je),k=1,ke)

Each processor reads a block subset of the arrays, and I've defined a
derived type using MPI_TYPE_INDEXED for the blocks that go to each
processor.  MPI_TYPE_INDEXED takes as arguments the number of blocks,
block size, and block displacement;  I created (and committed) the
datatype with the number of blocks/displacements 3 times (i.e.
subsetie*subsetje*subsetke*3) what I need for one variable above on a
given processor.  Then I used the following to read the file across the
processors:

count = subsetie*subsetje*subsetke
call MPI_FILE_SET_VIEW ( fh, skipheader, mpi_real8, newdatatype,
"native", mpi_info_null, ierror )
call MPI_FILE_READ_ALL ( fh, x, count, mpi_real8, ierror )
call MPI_FILE_READ_ALL ( fh, y, count, mpi_real8, ierror ) 
call MPI_FILE_READ_ALL ( fh, z, count, mpi_real8, ierror ) 

The result from this is x is read correctly, y and z are not.  However,
if I define one variable xyz(subsetie,subsetje,subsetke,3) and read all
the data in one call:

count = subsetie*subsetje*subsetke*3
call MPI_FILE_SET_VIEW ( fh, skipheader, mpi_real8, newdatatype,
"native", mpi_info_null, ierror )
call MPI_FILE_READ_ALL ( fh, xyz, count, mpi_real8, ierror )

everything is read correctly, which also verifies my derived type is
correct.  Alternatively I can reset the view (with correct
displacements) after each READ_ALL and read into the individual
variables.

Is this the expected behavior?  If so I do not understand how to make
successive collective reads from a file without resetting the view
before every read, which will take a toll on performance when I continue
to read many additional variables from the file.

Matt