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SDsetaccesstype/sfsacct

intn SDsetaccesstype(int32 sd_id, int32 access_type)
sd_id

IN:

SD interface identifier returned from SDstart

access_type

IN:

I/O access mode of the dataset

Purpose

Determines the I/O access mode to be used for the specified dataset.

Return value

Returns SUCCEED (or 0) if successful and FAIL (or -1) otherwise.

Description

The dataset must be an external element and the I/O access defined via this routine applies to the specified external file only.

The access_type parameter can be defined as DFACC_SERIAL for sequential I/O or DFACC_PARALLEL for parallel I/O. At present, HDF has only implemented the CM5 CMFS parallel I/O.

Though the access mode is set for dataset sds_id, it applies to the entire external file in which the dataset resides. If different access modes are defined for datasets within the same HDF external file, unpredictable effects will result. It is also the users' responsibility to make sure the access mode 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.

FORTRAN

integer function sfsacct(sd_id, access_type)

integer sd_id, access_type



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HDF User's Reference Manual, Draft 06/09/97, NCSA HDF Development Group.