27 lines
1.5 KiB
Markdown
27 lines
1.5 KiB
Markdown
Added two options to `git annex fsck` that allow for a form of distributed
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fsck. This is useful in situations where repositiories cannot be trusted to
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continue to exist, and cannot be checked directly, but you'd still like to
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keep track of their status. [[design/iabackup]] is one use case for this.
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By running a periodic fsck with the --distributed option,
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the repositories can verify that they still exist and that the
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information about their contents is still accurate. This is done by
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doing an extra update of the location log each time a file is verified by
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fsck to still be in the repository.
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The other option looks like --expire="30d somerepo:60d". It checks that
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each specified repository has recorded a distributed fsck within the specified
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time period. If not, the repository is dropped from the location tracking
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log. Of course it can always update that later if it's really still around.
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Distributed fsck is not the default because those extra location log updates
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increase the size of the git-annex branch. I did one thing to keep the size
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increase small: An identical line is logged to for each key, including the
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timestamp, so git's delta compression will work as well as is possible. But,
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there's still commit and tree update overhead.
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Probably doesn't make sense to run distributed fscks too often for that and
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other reasons. If the git-annex branch does get too large, there's always
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`git annex forget` ...
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**(Update: This was later rethought and works much more efficiently now..)**
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