What is a VFD?
A VFD in HDF5 is a "Virtual File Driver", which is the lowest layer in the HDF5 library and directly accesses some method of storing the file's information. Each VFD implements certain callback functions which are called from the upper layers of the library.
MPI-IO vs. MPI-POSIX:
- The MPI-IO VFD uses MPI File I/O calls, while the MPI-POSIX VFD uses POSIX file I/O calls
- Both use MPI to coordinate access to the file
- The MPI-IO VFD can perform collective I/O (on dataset elements)
Description of each parallel VFD: