43 lines
2.2 KiB
Markdown
43 lines
2.2 KiB
Markdown
Currently annex.thin needs hard link support to be efficient;
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it hard links the content from .git/annex/objects into the work tree.
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When hard links are not supported, two copies of checked out files exist on
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disk.
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Would it be possible to make it work w/o hard links? Note that direct mode
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does avoid two copies of files.
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IIRC the main reason for the hard link is so, when git checkout deletes a
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work tree file, the only copy of the file is not lost. Seems this would
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need a git hook run before checkout to rescue such files.
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Also some parts of git-annex's code, including `withObjectLoc`, assume
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that the .annex/objects is present, and so it would need to be changed
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to look at the work tree file. --[[Joey]]
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> Git hook is not sufficient. Consider the case of "rm file; git checkout file"
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> Without hard links, if the only copy of the annex object was in that
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> deleted file, it can't be restored. Now, direct mode did have the same
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> problem, but it didn't support `git checkout`, so the user didn't have
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> reason to expect such a workflow to work.
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>
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> So, I think this is not possible to implement in a way that won't
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> lead to users experiencing data loss when using it and doing
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> perfectly normal git things like this.
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>
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> (Although to be fair, annex.thin has its own data loss scenarios,
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> involving modifying a file potentially losing the only copy of
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> the old version. The difference, I think, is that with it,
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> you modify the file yourself and so lose the old version; the data
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> loss does not happen when you run git checkout or git pull!)
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>
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> In the meantime,
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> git-annex has gotten support for directory special remotes with
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> import/export tree. This can be used instead, for use cases such as a
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> device with a FAT filesystem. The git-annex repo can live on another
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> filesystem that does support hard links or symlinks, or where using
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> double disk space is not as much of a problem, or can even be a bare
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> git repo. That syncs up with the FAT device through tree import and
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> export. Once content has been imported to the git-annex repo,
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> the user can delete files from the FAT device without losing data.
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>
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> So this seems about as good as it can get. [[done]] --[[Joey]]
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