General Information

This version of ROMIO includes everything defined in the MPI I/O chapter except support for file interoperability and user-defined error handlers for files (§ 4.13.3). The subarray and distributed array datatype constructor functions from Chapter 4 (§ 4.14.4 & § 4.14.5) have been implemented. They are useful for accessing arrays stored in files. The functions MPI_File_f2c and MPI_File_c2f (§ 4.12.4) are also implemented. C, Fortran, and profiling interfaces are provided for all functions that have been implemented.

ROMIO has run on at least the following machines: IBM SP; Intel Paragon; HP Exemplar; SGI Origin2000; Cray T3E; NEC SX-4; other symmetric multiprocessors from HP, SGI, DEC, Sun, and IBM; and networks of workstations (Sun, SGI, HP, IBM, DEC, Linux, and FreeBSD). Supported file systems have at one time included IBM PIOFS, Intel PFS, HP/Convex HFS, SGI XFS, NEC SFS, PVFS, NFS, NTFS, and any Unix file system (UFS). You may have to download an older ROMIO or MPICH release for out-of-date systems.

This version of ROMIO is included in MPICH; an earlier version is included in at least the following MPI implementations: LAM, HP MPI, SGI MPI, and NEC MPI. Many HPC vendors base their MPI-IO implementation on ROMIO.

Note that proper I/O error codes and classes are returned and the status variable is filled only when used with MPICH revision 1.2.1 or later.

You can open files on multiple file systems in the same program. The only restriction is that the directory where the file is to be opened must be accessible from the process opening the file. For example, a process running on one workstation may not be able to access a directory on the local disk of another workstation, and therefore ROMIO will not be able to open a file in such a directory. NFS-mounted files can be accessed.

An MPI-IO file created by ROMIO is no different from any other file created by the underlying file system. Therefore, you may use any of the commands provided by the file system to access the file, for example, ls, mv, cp, rm, ftp.

Please read the limitations of this version of ROMIO that are listed in Section 7 of this document (e.g., restriction to homogeneous environments).

Rob Latham 2016-08-01