38 lines
1.5 KiB
Markdown
38 lines
1.5 KiB
Markdown
In both the .git/annex directory and the git-annex branch, two levels of
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hash directories are used, to avoid issues with too many files in one
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directory.
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Two separate hash methods are used.
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* hashdirmixed is only used for non-bare git repositories.
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(We'd like to stop using this, but it'd be too annoying to change
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all the git-annex symlinks!)
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* hashdirlower is used for bare git repositories, the
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git-annex branch, and on special remotes as well.
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Note that `git annex find` and `git annex examinekey` can be used with
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the `--format` option to find the hash directories. The explanation
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below is only for completeness.
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## new hash format
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This uses two directories, each with a three-letter name, such as "f87/4d5"
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The directory names come from the md5sum of the [[key|key_format]].
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For example:
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echo -n "SHA256E-s0--e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855" | md5sum
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## old hash format
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This uses two directories, each with a two-letter name, such as "pX/1J"
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It takes the md5sum of the key, but rather than a string, represents it as 4
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32bit words. Only the first word is used. It is converted into a string by the
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same mechanism that would be used to encode a normal md5sum value into a
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string, but where that would normally encode the bits using the 16 characters
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0-9a-f, this instead uses the 32 characters "0123456789zqjxkmvwgpfZQJXKMVWGPF".
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The first 2 letters of the resulting string are the first directory, and the
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second 2 are the second directory.
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