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It is and people do use it, but it ultimately still exists as software that sits on top of POSIX in the vast majority of cases. It can clean up really bad POSI
by glennklockwood 9y ago
It is and people do use it, but it ultimately still exists as software that sits on top of POSIX in the vast majority of cases. It can clean up really bad POSIX I/O by buffering and reordering, but doing so induces latency, memory overheads, and consumes other resources that don't always pay dividends at all scales.
- gnufx 9y agoROMIO 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.