Boosting I/O and visualization for exascale era using Hercule: test case
  on RAMSES
  It has been clearly identified that I/O is one of the bottleneck to extend
application for the exascale era. New concepts such as 'in transit' and 'in
situ' visualization and analysis have been identified as key technologies to
circumvent this particular issue. A new parallel I/O and data management
library called Hercule, developed at CEA-DAM, has been integrated to Ramses, an
AMR simulation code for self-gravitating fluids. Splitting the original Ramses
output format in Hercule database formats dedicated to either
checkpoints/restarts (HProt format) or post-processing (HDep format) not only
improved I/O performance and scalability of the Ramses code but also introduced
much more flexibility in the simulation outputs to help astrophysicists prepare
their DMP (Data Management Plan). Furthermore, the very lightweight and
purpose-specific post-processing format (HDep) will significantly improve the
overall performance of analysis and visualization tools such as PyMSES 5. An
introduction to the Hercule parallel I/O library as well as I/O benchmark
results will be discussed.
