> Have you tried? The very principle of Git makes it necessary, to remove
> or update old data, to rewrite the whole subsequent history.
> Furthermore, it is done by creating a new branch, the original data is
> not actually deleted.
`git gc` does delete the old data (if it's not reachable any more).
BTW, if you want to (ab)use a Git repository to do backups, you should
definitely look at `bup`.
Stefan