git-annex can transfer data to and from configured git remotes. Normally those remotes are normal git repositories (bare and non-bare; local and remote), that store the file contents in their own git-annex directory.
But, git-annex also extends git's concept of remotes, with these special types of remotes. These can be used just like any normal remote by git-annex. They cannot be used by other git commands though.
The above special remotes can be used to tie git-annex into many cloud services. Here are specific instructions for various cloud things:
Unused content on special remotes
Over time, special remotes can accumulate file content that is no longer
referred to by files in git. Normally, unused content in the current
repository is found by running
git annex unused. To detect unused content
on special remotes, instead use
git annex unused --from. Example:
$ git annex unused --from mys3 unused mys3 (checking for unused data...) Some annexed data on mys3 is not used by any files in this repository. NUMBER KEY 1 WORM-s3-m1301674316--foo (To see where data was previously used, try: git log --stat -S'KEY') (To remove unwanted data: git-annex dropunused --from mys3 NUMBER) $ git annex dropunused --from mys3 1 dropunused 12948 (from mys3...) ok