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/** \page Files
\section secFiles Files
\subsection CB_FreeSpace Tracking Free Space in HDF5 Files
\par Problem
You sometimes delete objects in HDF5 files and don't have new content to use the
free space, but would like to reuse it in the future.
\par Solution
At file creation time, set the file space management strategy and persistence of
free space tracking information via H5Pset_file_space_strategy().
\note This feature is only supported in HDF5 1.10.1+.
\snippet{lineno} Files.c free_space
\par Discussion
Free space tracking is supported only in HDF5 versions 1.10.x and higher.
This has implications for the accessibility of your HDF5 files and
should be considered carefully. If compatibility with previous versions of
HDF5 must be maintained, space reclamation via \Code{h5repack} might be an option.\n
The file space strategy #H5F_FSPACE_STRATEGY_FSM_AGGR is not the only option
that supports free-space tracking. #H5F_FSPACE_STRATEGY_PAGE is another option,
which adds paged allocation and is used most effectively with page buffering.\n
For an in-depth account of HDF5 file space management, paged-allocation, and
page buffering, see the following documents:
\li \ref_rfc20121024
\li \ref_rfc20120523
\li \ref_rfc20150709
\par See Also
See \ref CB_MaintainCompat for HDF5 compatibility implications.
\subsection CB_RemoveUnusedSpace Removing Unused Space from HDF5 Files
\par Problem
Based on estimates or \Code{h5stat} output you know that a large portion
of an HDF5 file consists of free or unaccounted space, and you would like
to remove it.
\subsection CB_UserBlock Creating an HDF5 File User Block
\par Problem
You would like to include certain ancillary, non-HDF5 content in an
HDF5 file such that it can be accessed without the HDF5 library.
\par Solution
Use a file creation property list in which the user block size is set via
H5Pset_userblock(). In the example below, we create an 8 MiB user block.
\snippet{lineno} Files.c user_block
\par Discussion
The user block begins at offset 0 and must be at least 512 bytes and a power
of 2. The HDF5 library ignores any content between the beginning of the
file and the end of the user block.\n
You can add or strip a user block to/from an existing HDF5 file with the
\Code{h5jam}/\Code{h5unjam} tool, respectively.
\warning
If you try to embed content into the user block for use by other applications,
pay close attention to how they handle space beyond the last used byte in the
user block or the user block in general. In the worst case, applications might
try to truncate the rest of the file and destroy the HDF5 portion of the file.
\par See Also
References to related recipes
*/
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