[ceph-users] rbd-mirror - which direction?

Hello, i am running luminous and i would like to back up my cluster from Site-A to Site-B (one way) So i decided to mirror it to an off-site ceph cluster. I read: https://docs.ceph.com/docs/luminous/rbd/rbd-mirroring/ But i liked I https://github.com/MiracleMa/Blog/issues/2 a little better. But which parameter/part show the direction it will mirror? Thanks, Mario