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diff --git a/tools/h5recover/README_Journaling b/tools/h5recover/README_Journaling new file mode 100644 index 0000000..971fe54 --- /dev/null +++ b/tools/h5recover/README_Journaling @@ -0,0 +1,47 @@ + HDF5 Metadata Journaling Alpha1 Release + +Feature Description +=================== +The metadata journaling feature will keep a journal file of metadata being +written to an HDF5 file. Whenever the HDF5 file is flushed (H5Fflush) +or closed (H5Fclose) successfully, that is all metadata are written to +the file for sure, the journal file will be reset anew. + +If the application that opens the HDF5 file crashes before the file is +closed, the file could be in an unstable state. If the file has been opened with +journaling enabled, the user can recover the file by the h5recover tool +with the journal file. All metadata are guaranteed to be stable but +rawdata modifications are not. + +Release Description +=================== +This is an alpha1 release. The Metadata Journaling feature is implemented +and is available for friendly users test. Be advised that there may be +further changes of the programming API and the file format. Therefore, +users are advised to use this release for testing purpose only. + +How to use the Metadata Journaling feature +========================================== +An example application using the Metadata Journaling feature is +included in the source code as tools/h5recover/enable_journaling.c. To +enable Metadata Journaling, one should copy the function routine, +set_journaling(), to its own application program code and call +set_journaling() as demonstrated in the enable_journaling.c example. + +To test run the enable_journaling example, follow these steps +(assuming the hdf5 library is installed in the following location, +/projects/sio/acheng/HDF5/MDJ_a1/tbird): + +% /projects/sio/acheng/HDF5/MDJ_a1/tbird/bin/h5cc enable_journaling.c -o enable_journaling +% ./enable_journaling -c # create the data file, JournalEG.h5 +% ./enable_journaling -w # write more rows to the data file. + # Interrupt the application at any point. +% /projects/sio/acheng/HDF5/MDJ_a1/tbird/bin/h5dump JournalEG.h5 # h5dump would fail +% /projects/sio/acheng/HDF5/MDJ_a1/tbird/bin/h5recover -j JournalEG.h5.jnl JournalEG.h5 # recover the data file with the Journaling file +% /projects/sio/acheng/HDF5/MDJ_a1/tbird/bin/h5dump JournalEG.h5 # h5dump would succeed now. +% ./enable_journaling -w # can write more rows to the data file again. + + +==================== +Contact acheng@hdfgroup.org for any question. +Last updated: Sep 1st, 2008. |