Data Access With Individual File Pointers

For each open file, Sun MPI I/O maintains one individual file pointer per process per collective MPI_File_open. For these data-access routines, MPI I/O implicitly uses the value of the individual file pointer. These routines use and update only the individual file pointers maintained by MPI I/O by pointing to the next elementary data type after the one that has most recently been accessed. The individual file pointer is updated relative to the current view of the file. The shared file pointer is neither used nor updated. (For data access with shared file pointers, please see the next section.)

These routines have similar semantics to the explicit-offset data-access routines, except that the offset is defined here to be the current value of the individual file pointer.

MPI_File_read_all and MPI_File_write_all are collective versions of MPI_File_read and MPI_File_write, with each process using its individual file pointer.

MPI_File_iread and MPI_File_iwrite are the nonblocking versions of MPI_File_read and MPI_File_write, respectively. The split collective versions of MPI_File_read_all and MPI_File_write_all are listed in the table at the beginning of this section.