In the world of git, we're not scared about internal implementation details, and sometimes we like to dive in and tweak things by hand. Here's some documentation to that end.
This is where locally available file contents are actually stored. Files added to the annex get a symlink checked into git that points to the file content.
First there are two levels of directories used for hashing, to prevent too many things ending up in any one directory. See hashing for details.
Each subdirectory has the name of a key in one of the key-value backends. The file inside also has the name of the key. This two-level structure is used because it allows the write bit to be removed from the subdirectories as well as from the files. That prevents accidentially deleting or changing the file contents. See lockdown for details.
In direct mode, file contents are not stored in here, and instead are stored directly in the file. However, the same symlinks are still committed to git, internally.
Also in direct mode, some additional data is stored in these directories.
.cache files contain cached file stats used in detecting when a file has
.map files contain a list of file(s) in the work directory
that contain the key.
The git-annex branch
This branch is managed by git-annex, with the contents listed below.
.git/annex/index is a separate git index file it uses
to accumulate changes for the git-annex branch.
.git/annex/journal/ is used to record changes before they
are added to git.
This branch operates on objects exclusively. No file names will ever be stored in this branch.
Records the UUIDs of known repositories, and associates them with a description of the repository. This allows git-annex to display something more useful than a UUID when it refers to a repository that does not have a configured git remote pointing at it.
The file format is simply one line per repository, with the uuid followed by a space and then the description, followed by a timestamp. Example:
e605dca6-446a-11e0-8b2a-002170d25c55 laptop timestamp=1317929189.157237s 26339d22-446b-11e0-9101-002170d25c55 usb disk timestamp=1317929330.769997s
If there are multiple lines for the same uuid, the one with the most recent timestamp wins. git-annex union merges this and other files.
Holds persistent configuration settings for special remotes such as Amazon S3.
The file format is one line per remote, starting with the uuid of the remote, followed by a space, and then a series of var=value pairs, each separated by whitespace, and finally a timestamp.
Encrypted special remotes store their encryption key here, in the "cipher" value. It is base64 encoded, and unless shared encryption is used, is encrypted to one or more gpg keys. The first 256 bytes of the cipher is used as the HMAC SHA1 encryption key, to encrypt filenames stored on the special remote. The remainder of the cipher is used as a gpg symmetric encryption key, to encrypt the content of files stored on the special remote.
The file format is one line per repository, with the uuid followed by a
space, and then either
X (dead) and finally a timestamp.
e605dca6-446a-11e0-8b2a-002170d25c55 1 timestamp=1317929189.157237s 26339d22-446b-11e0-9101-002170d25c55 ? timestamp=1317929330.769997s
Repositories not listed are semi-trusted.
Used to group repositories together.
The file format is one line per repository, with the uuid followed by a space, and then a space-separated list of groups this repository is part of, and finally a timestamp.
Used to indicate which repositories prefer to contain which file contents.
The file format is one line per repository, with the uuid followed by a space, then a boolean expression, and finally a timestamp.
Files matching the expression are preferred to be retained in the repository, while files not matching it are preferred to be stored somewhere else.
The name of the key is the filename, and the content consists of a timestamp, either 1 (present) or 0 (not present), and the UUID of the repository that has or lacks the file content.
1287290776.765152s 1 e605dca6-446a-11e0-8b2a-002170d25c55 1287290767.478634s 0 26339d22-446b-11e0-9101-002170d25c55
These files are designed to be auto-merged using git's union merge driver. The timestamps allow the most recent information to be identified.
These log files record urls used by the web special remote. Their format is similar to the location tracking files, but with urls rather than UUIDs.