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H5P_SET_CORE_WRITE_TRACKING

Sets write tracking information for core driver, H5FD_CORE

Procedure:

H5P_SET_CORE_WRITE_TRACKING ( fapl_id, is_enabled, page_size )

Signature:

herr_t H5Pset_core_write_tracking(
              hid_t fapl_id, 
              hbool_t is_enabled, 
              size_t page_size
         )
         

Parameters:
hid_t fapl_idIN: File access property list identifier
hbool_t is_enabled  IN: Boolean value specifying whether feature is enabled
size_t page_sizeIN: Positive integer specifying size, in bytes, of write aggregation pages
Value of 1 (one) enables tracking with no paging.

Description:

When a file is created or opened for writing using the core virtual file driver (VFD) with the backing store option turned on, the core driver can be configured to track changes to the file and write out only the modified bytes.

This write tracking feature is enabled and disabled with is_enabled. The default setting is that write tracking is disabled, or off.

To avoid a large number of small writes, changes can be aggregated into pages of a user-specified size, page_size.

Setting page_size to 1 enables tracking with no page aggregation.

The backing store option is set via the function H5Pset_fapl_core.

This function is only for use with the core VFD and must be used after the call to H5P_SET_FAPL_CORE. It is an error to use this function with any other VFD.

It is an error to use this function when the backing store flag has not been set using H5P_SET_FAPL_CORE.

This function only applies to the backing store write operation which typically occurs when the file is flushed or closed. This function has no relationship to the increment parameter passed to H5P_SET_FAPL_CORE.

For optimum performance, the page_size parameter should be a power of two.

 

It is an error to set the page size to 0.

 

Returns:

Returns a non-negative value if successful. Otherwise returns a negative value.

Example:

Coming Soon!

History:
ReleaseChange
1.8.13C function introduced with this release.
1.8.14C function modified in this release to return error if page_size is set to 0 (zero).

--- Last Modified: December 04, 2017 | 08:38 AM