Acredito que você deseja a opção -xx
:
-x, --one-file-system
This tells rsync to avoid crossing a filesystem boundary when recursing. This does not limit the user's ability to specify items to copy from multiple filesystems, just rsync's recursion through the hierarchy of each directory that the user specified, and also the analogous recursion on the receiving side during deletion. Also keep in mind that rsync treats a lqbindrq mount to the same device as being on the same filesystem.If this option is repeated, rsync omits all mount-point directories from the copy. Otherwise, it includes an empty directory at each mount-point it encounters (using the attributes of the mounted directory because those of the underlying mount-point directory are inaccessible).
O motivo pelo qual digo -xx
é devido à seção em negrito (ênfase adicionada).