Changes between Initial Version and Version 1 of Ticket #67336, comment 37
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- Oct 4, 2024, 7:07:30 PM (6 days ago)
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Ticket #67336, comment 37
initial v1 1 To reiterate: The files are correct on disk . For a time after the file is created, the disk cache erroneously tells anyone who asks that the file contains holes where it does not contain holes anymore. BSD tar uses this information to skip those areas of the file when archiving, so the file is corrupted at the time of archiving; nothing can be done at extract time to recover the missing information. BSD tar has no option to tell it not to do this until version 3.6.0 and even macOS 15 does not yet include a version that new. GNU tar can also do this and experiences the same problem if told to do so but does not do so by default. Clearing the disk cache works around the problem but can only be done as root.1 To reiterate: The files are correct on disk before being archived. For a time after the file is created, the disk cache erroneously tells anyone who asks that the file contains holes where it does not contain holes anymore. BSD tar uses this information to skip those areas of the file when archiving, so the file is corrupted at the time of archiving; nothing can be done at extract time to recover the missing information. BSD tar has no option to tell it not to do this until version 3.6.0 and even macOS 15 does not yet include a version that new. GNU tar can also do this and experiences the same problem if told to do so but does not do so by default. Clearing the disk cache works around the problem but can only be done as root. 2 2 3 3 I didn't know about tcllib's tar module. The [https://wiki.tcl-lang.org/page/Tcllib+tar page I found about it] doesn't say much. If it can create archives that do not attempt to represent files sparsely, then using it instead of the system's tar to create archives would work around the problem.