Is git push --mirror sufficient as a backup for repository that is used with git-svn?

Question

I would like to create a backup of a git repository that I use for tracking a svn repository (with git-svn). Can I use git push --mirror for that purpose or would I lose any git-svn related information when I needed to restore the backup?

Answer 1

It is possible git push or git bundle do not include svn metadata.

But according to git svn intro, you could then try and restore those svn metadata.
(disclaimer: not tested directly)

Rebuilding git-svn metadata

If you copied the repository from somewhere else (eg, from repo.utsl.gen.nz) via git-clone, or if you just blew it away, then you won't have any SVN metadata - just commits.
In that case, you need to rebuild your SVN metadata, for instance, for just keeping trunk up to date - git-svn will rebuild its metadata when you run git-svn fetch.

$ git update-ref refs/remotes/trunk origin/svn/trunk
$ git svn init https://svn.perl.org/parrot/trunk
Using higher level of URL: https://svn.perl.org/parrot/trunk => https://svn.perl.org/parrot
$ git svn fetch
Rebuilding .git/svn/git-svn/.rev_db.d31e2699-5ff4-0310-a27c-f18f2fbe73fe ...
r17220 = 78ad11bf2f61b35e1cb32a978ab546d198be8a2e
r17219 = 605264b06d84670ec402d7a7a21c0016cae3a928
r17218 = a8ceba9c503d2be8e8e69a3df454017322906cf5
...

The key thing to remember with rebuilding git-svn metadata is to make the refs look just like they would look from a fresh import; you can do this using git update-ref as above, by copying refs files around inside .git/refs/, or using git pack-refs then editing .git/packed-refs.
To test that you got it right, use git show-ref - perhaps compare with a fresh SVN HEAD clone.