[ceph-users] about rbd-nbd auto mount at boot time

want to auto mount the ceph blockdriver at the boot time .becauseI use RBD-mirror,I just only can use nbd type to mount the blockdriver.I try to use /etc/ceph/rbdmap and /etc/fstab with _netdev.But I find it cann't mount at boot time.It just map for ndb type as /dev/nbd0.I need to mount manually use command "mount /dev/nbd0 /mnt".Has anyone solved this problem?