Parallel and Large-scale Simulation Enhancements to CGNS
5 Aug 2015 -
Scot Breitenfeld from The HDF Group describes on the group blog parallel file extensions to CGNS. The CFD General Notation System (CGNS) provides a general, portable, and extensible standard for the storage and retrieval of computational fluid dynamics (CFD) analysis data. It consists of a collection of conventions, and free and open software implementing those conventions. It is self-descriptive, machine-independent, well-documented, and administered by an international steering committee. It is also an American Institute of Aeronautics and Astronautics (AIAA) Recommended Practice.
CGNS data was originally stored using a file format called ADF ('Advanced Data Format'), but ADF does not have parallel I/O or data compression capabilities, and does not have the support base and tools that HDF5 offers. ADF has since been superseded by the Hierarchical Data Format, Version 5 (HDF5) as the official default underlying storage mechanism for CGNS.
In 2014, NASA provided funding for The HDF Group to improve the under-performing parallel capabilities of the CGNS library.
The following results are from CGNS benchmark programs created during the course of the project, writes Breitenfeld. The benchmarks simulate writing and then reading a ~33.5 million, 6-node pentahedra element mesh with ~201 million nodes. The figure highlights just one of the available benchmarks by comparing the maximum I/O bandwidth speeds for reading and writing CGNS data compared to the practical maximum I/O bandwidth on Argonne National Laboratory (ANL's) Cetus computer, and it shows the extremely fast writing of the element connectivity table.