sdsetaccesstype(3hdf)

sds_id
IN: The dataset ID returned from SDselect
accesstype
IN: The type of I/O access for the dataset.

Set the I/O access type for the dataset.

Returns SUCCEED if successful and FAIL otherwise.

SDsetaccesstype sets the I/O access type for the dataset sds_id to accesstype. The dataset must be an external element and the I/O access applies to the related external file only. accesstype can be DFACC_SERIAL for sequential I/O or DFACC_PARALLEL for parallel I/O. HDF has only implemented the CM5 CMFS parallel I/O.

Though access type is set for dataset sds_id, it applies to the whole external file in which the dataset resides. If different access types are set on datasets of the same HDF external file, unpredictable effects will result. It is also the users' responsibility to make sure the access type is appropriate for the files involved. For example, setting DFACC_PARALLEL on a dataset contained in a serial file may result in slower I/O rates and sometimes failures.

integer function sfacct(sds_id, accesstype)
integer*4 sds_id, accesstype