We "lose" the iscsi device after a reboot - i.e., it appears in /dev/rdsk and /dev/dsk but format cannot find it. Obviously, it won't mount either. This happens for two separately defined luns.
We must be missing a step in iscsiadm.
The luns are defined as targets, we can see them in iscsiadm. We are not exporting them, so there is no backing store.