How do you organise multiple git repositories, so that all of them are backed up together?

Question

With SVN, I had a single big repository I kept on a server, and checked-out on a few machines. This was a pretty good backup system, and allowed me easily work on any of the

Answer 1

I would strongly advise against putting unrelated data in a given Git repository. The overhead of creating new repositories is quite low, and that is a feature that makes it possible to keep different lineages completely separate.

Fighting that idea means ending up with unnecessarily tangled history, which renders administration more difficult and--more importantly--"archeology" tools less useful because of the resulting dilution. Also, as you mentioned, Git assumes that the "unit of cloning" is the repository, and practically has to do so because of its distributed nature.

One solution is to keep every project/package/etc. as its own bare repository (i.e., without working tree) under a blessed hierarchy, like:

/repos/a.git
/repos/b.git
/repos/c.git

Once a few conventions have been established, it becomes trivial to apply administrative operations (backup, packing, web publishing) to the complete hierarchy, which serves a role not entirely dissimilar to "monolithic" SVN repositories. Working with these repositories also becomes somewhat similar to SVN workflows, with the addition that one can use local commits and branches:

svn checkout   --> git clone
svn update     --> git pull
svn commit     --> git push

You can have multiple remotes in each working clone, for the ease of synchronizing between the multiple parties:

$ cd ~/dev
$ git clone /repos/foo.git       # or the one from github, ...
$ cd foo
$ git remote add github ...
$ git remote add memorystick ...

You can then fetch/pull from each of the "sources", work and commit locally, and then push ("backup") to each of these remotes when you are ready with something like (note how that pushes the same commits and history to each of the remotes!):

$ for remote in origin github memorystick; do git push $remote; done

The easiest way to turn an existing working repository ~/dev/foo into such a bare repository is probably:

$ cd ~/dev
$ git clone --bare foo /repos/foo.git
$ mv foo foo.old
$ git clone /repos/foo.git

which is mostly equivalent to a svn import--but does not throw the existing, "local" history away.

Note: submodules are a mechanism to include shared related lineages, so I indeed wouldn't consider them an appropriate tool for the problem you are trying to solve.