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The following are the sections on this page:

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strategy
strategy
File Space Management Strategies

The HDF5 library uses three mechanisms to manage space in an HDF5 file. They are:

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There are four file space-handling strategies available to users that use these mechanisms:

H5F_FSPACE_STRATEGY_FSM_AGGR

This strategy has always been available in HDF5 and is the default. The mechanisms used for this strategy are free-space managers, aggregators, and virtual file drivers.

H5F_FSPACE_STRATEGY_PAGE

The current HDF5 file space allocation accumulates small pieces of metadata and raw data in aggregator blocks. However, these blocks are not page aligned and vary widely in sizes. The paged aggregation feature provides efficient paged access of these small pieces of metadata and raw data. It accumulates metadata and raw data into well-aligned pages called file space pages. The library defines a default file space page size but a user can set the page size via a new public routine.

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See the RFC on this feature for complete details.

H5F_FSPACE_STRATEGY_AGGR

With this strategy the library will request space from either the metadata or raw data aggregator depending on the file space type. If the request is not satisfied, the library will request space from the virtual file driver.

The mechanisms used for this strategy are aggregators and virtual file drivers. It does not use the free-space manager.

H5F_FSPACE_STRATEGY_NONE

This strategy will request space from the virtual file driver. The only mechanism used is the virtual file driver. It does not use the free-space manager.

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userguide
userguide
File Space Management User’s Guide

(This document is not yet available.)

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libapi
libapi
HDF5 Library APIs

The APIs listed below from the HDF5 Reference Manual provide a means for users to directly manage the file space management feature.

  
H5Fget_free_sectionsRetrieves free-space section information for a file
H5Fget_freespaceReturns the amount of free space in a file
H5Fget_info2Returns global information for a file
H5Pget_file_space_strategyRetrieves the File Space Strategy for a file creation property list
H5Pset_file_space_strategySets the File Space Strategy for a file creation property list
H5Pget_file_space_page_sizeRetrieves the file space page size for paged aggregation
H5Pset_file_space_page_sizeSets the file space page size for paged aggregation

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tools
tools
Tools

The tools listed below have been modified to preserve or modify file freepace information appropriately when processing files employing this feature.

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