+In order to preserve usernames and groupnames, rsync needs to be able to
+lookup the IDs using getpuid() and getpgid(). This means that the chroot
+area will need to have copies of your user/group information (edited, if
+desired) inside the chroot tree for rsync to use (the traditional files
+are /etc/passwd and /etc/group). If the needed files are not available,
+rsync will only be able to copy the IDs, just as if the --numeric-ids
+option had been specified.
+