Last modified: 14 October 2014
Name: H5Pset_fapl_multi
Signature:
  herr_t `H5Pset_fapl_multi`( hid_t `fapl_id`, const H5FD_mem_t *`memb_map`, const hid_t *`memb_fapl`, const char * const *`memb_name`, const haddr_t *`memb_addr`, hbool_t `relax` )
Purpose:
  Sets up use of the multi-file driver.
Description:
  `H5Pset_fapl_multi` sets the file access property list `fapl_id` to use the multi-file driver.

  The multi-file driver enables different types of HDF5 data and metadata to be written to separate files. These files are viewed by the HDF5 library and the application as a single virtual HDF5 file with a single HDF5 file address space. The types of data that can be broken out into separate files include raw data, the superblock, B-tree data, global heap data, local heap data, and object headers. At the programmer's discretion, two or more types of data can be written to the same file while other types of data are written to separate files.

  The array `memb_map` maps memory usage types to other memory usage types and is the mechanism that allows the caller to specify how many files are created. The array contains `H5FD_MEM_NTYPES` entries, which are either the value `H5FD_MEM_DEFAULT` or a memory usage type. The number of unique values determines the number of files that are opened.

  The array `memb_fapl` contains a property list for each memory usage type that will be associated with a file.

  The array `memb_name` should be a name generator (a printf-style format with a %s which will be replaced with the name passed to `H5FDopen`, usually from `H5Fcreate` or `H5Fopen`).

  The array `memb_addr` specifies the offsets within the virtual address space, from `0` (zero) to `HADDR_MAX`, at which each type of data storage begins.

  If `relax` is set to `TRUE` (or `1`), then opening an existing file for read-only access will not fail if some file members are missing. This allows a file to be accessed in a limited sense if just the meta data is available.

  Default values for each of the optional arguments are as follows:

  `memb_map`
    The default member map contains the value `H5FD_MEM_DEFAULT` for each element.
  `memb_fapl`
    The default value is `H5P_DEFAULT` for each element.
  `memb_name`
    The default string is `%s-X.h5` where `X` is one of the following letters: `s` for `H5FD_MEM_SUPER`
    `b` for `H5FD_MEM_BTREE`
    `r` for `H5FD_MEM_DRAW`
    `g` for `H5FD_MEM_GHEAP`
    `l` for `H5FD_MEM_LHEAP`
    `o` for `H5FD_MEM_OHDR`
  `memb_addr`
    The default setting is that the address space is equally divided among all of the elements:

        H5FD_MEM_SUPER -> 0 * (HADDR_MAX/6)
        H5FD_MEM_BTREE -> 1 * (HADDR_MAX/6)
        H5FD_MEM_DRAW -> 2 * (HADDR_MAX/6)
        H5FD_MEM_GHEAP -> 3 * (HADDR_MAX/6)
        H5FD_MEM_LHEAP -> 4 * (HADDR_MAX/6)
        H5FD_MEM_OHDR -> 5 * (HADDR_MAX/6)

Parameters:

hid_t `fapl_id` | IN: File access property list identifier.
const H5FD_mem_t *`memb_map` | IN: Maps memory usage types to other memory usage types.
const hid_t *`memb_fapl` | IN: Property list for each memory usage type.
const char * const *`memb_name` | IN: Name generator for names of member files.
const haddr_t *`memb_addr` | IN: The offsets within the virtual address space, from `0` (zero) to `HADDR_MAX`, at which each type of data storage begins.
hbool_t `relax` | IN: Allows read-only access to incomplete file sets when `TRUE`.

Returns:
  Returns a non-negative value if successful. Otherwise returns a negative value.
Example:
  The following code sample sets up a multi-file access property list that partitions data into meta and raw files, each being one-half of the address:

                        H5FD_mem_t mt, memb_map[H5FD_MEM_NTYPES];
                        hid_t memb_fapl[H5FD_MEM_NTYPES];
                        const char *memb[H5FD_MEM_NTYPES];
                        haddr_t memb_addr[H5FD_MEM_NTYPES];

                        // The mapping...
                        for (mt=0; mt<H5FD_MEM_NTYPES; mt++) {
                           memb_map[mt] = H5FD_MEM_SUPER;
                        }
                        memb_map[H5FD_MEM_DRAW] = H5FD_MEM_DRAW;

                        // Member information
                        memb_fapl[H5FD_MEM_SUPER] = H5P_DEFAULT;
                        memb_name[H5FD_MEM_SUPER] = "%s.meta";
                        memb_addr[H5FD_MEM_SUPER] = 0;

                        memb_fapl[H5FD_MEM_DRAW] = H5P_DEFAULT;
                        memb_name[H5FD_MEM_DRAW] = "%s.raw";
                        memb_addr[H5FD_MEM_DRAW] = HADDR_MAX/2;

                        hid_t fapl = H5Pcreate(H5P_FILE_ACCESS);
                        H5Pset_fapl_multi(fapl, memb_map, memb_fapl,
                                        memb_name, memb_addr, TRUE);

Fortran90 Interface: h5pset_fapl_multi_f

      SUBROUTINE h5pset_fapl_multi_f(prp_id, memb_map, memb_fapl, memb_name,
                                     memb_addr, relax, hdferr)
        IMPLICIT NONE
        INTEGER(HID_T),INTENT(IN)  :: prp_id     ! Property list identifier

        INTEGER,DIMENSION(H5FD_MEM_NTYPES_F),INTENT(IN)          :: memb_map
        INTEGER(HID_T),DIMENSION(H5FD_MEM_NTYPES_F),INTENT(IN)   :: memb_fapl
        CHARACTER(LEN=*),DIMENSION(H5FD_MEM_NTYPES_F),INTENT(IN) :: memb_name
        REAL, DIMENSION(H5FD_MEM_NTYPES_F), INTENT(IN)           :: memb_addr
                    ! Numbers in the interval [0,1) (e.g. 0.0 0.1 0.5 0.2 0.3 0.4)
                    ! real address in the file will be calculated as X*HADDR_MAX

        LOGICAL, INTENT(IN)  :: relax
        INTEGER, INTENT(OUT) :: hdferr           ! Error code
                                                 ! 0 on success and -1 on failure
      END SUBROUTINE h5pset_fapl_multi_f

History:

Release | C
1.6.3 | `memb_name` parameter type changed to const char* const*.
1.4.0 | Function introduced in this release.