H5Pset_alignment sets the alignment properties of a file access property list so that any file object greater than or equal in size to
threshold bytes will be aligned on an address which is a multiple of
alignment. The addresses are relative to the end of the user block; the alignment is calculated by subtracting the user block size from the absolute file address and then adjusting the address to be a multiple of
Default values for
alignment are one, implying no alignment. Generally the default values will result in the best performance for single-process access to the file. For MPI IO and other parallel systems, choose an alignment which is a multiple of the disk block size.
If the file space handling strategy is set to
H5F_FSPACE_STRATEGY_PAGE, then the alignment set via this routine is ignored. The file space handling strategy is set by