Hi I am getting a zero-sized file "foo.info" when I write a vector, say "my_vec", to disk file "foo":
MPI_Comm comm; PetscViewer viewer; Vec my_vec; ... PetscViewerBinaryOpen(comm, "foo", FILE_MODE_WRITE, &viewer); VecView(my_vec, viewer); PetscViewerDestroy(viewer); My questions are: 1. Can I safely ignore the .info file? (Is it useful?) 2. How can I prevent the .info file from being generated? Thanks, Shao-Ching Matthew Knepley wrote: > On Thu, Feb 5, 2009 at 7:48 PM, Shao-Ching Huang <schuang at ats.ucla.edu> > wrote: >> Hi, >> >> I am trying to create restart/check-pointing files for a time-stepping >> simulation (by writing out vectors to files). >> >> 1. Does VecView always use the MPI collective I/O? >> >> The HTML documentation of PetscViewerBinaryOpen says: "For writing >> files it only opens the file on processor 0 in the communicator." > > You must run with -viewer_binary_mpiio. However, I recommend very very > strongly that you profile this first. We have not need to use MPI/IO below > several thousand processors. > >> 2. Do I have to set anything to enable MPI I/O when configuring PETSc? >> (My MPI library has MPI I/O.) > > This should happen automatically. > > Matt > >> Thank you. >> >> Shao-Ching
