ROMIO unfortunately requires global locking on Lustre, but I don't see how that's relevant to the use of standard or other high-level (HDF, NetCDF, ...) non-POS

ROMIO unfortunately requires global locking on Lustre, but I don't see how that's relevant to the use of standard or other high-level (HDF, NetCDF, ...) non-POSIX interfaces. You can swap in PVFS, or something else with a different architecture. (So what if object stores are on _local_ POSIX-y filesystems?) I'd have thought the salient feature is collective i/o, not cleaning up silly POSIX i/o of some sort. Nothing's perfect, but what should replace the non-blocking collective MPI-IO under5, for instance? I wonder what are the major NERSC applications that don't do sane i/o and should. The published workload characterization doesn't help.