If you fail to share a zfs pool on the mds, then nfs will not be enabled and therefore the mds auth records will not load.

#  mdsadm -o add -t auth -a ip=10.1.233.117
adding: IP Addr - 10.1.233.117
Mar 20 20:37:41 pnfs-3-15 nfs: NFS Server not loaded
# zpool create -f nippy /dev/dsk/c1t0d0s7
#  echo '::walk Device_entry_cache | ::print struct rfs4_dbe data | ::print mds_device_t' | mdb -k

mdb: failed to perform walk: unknown walk name

Above we see mdsadm clearly telling us we have an issue. And the fact that we can't use our simple mdb command to see the auth records is a worry.Just as I rebooted, I realized what the problem was. And we can check it out:

#  mdsadm -o add -t auth -a ip=10.1.233.117
adding: IP Addr - 10.1.233.117
Mar 20 20:42:54 pnfs-3-15 nfs: NFS Server not loaded
# echo '::walk Device_entry_cache | ::print struct rfs4_dbe data | ::print mds_device_t' | mdb -k
mdb: failed to perform walk: unknown walk name
# echo '::walk Device_entry_cache | ::print struct rfs4_dbe data | ::print mds_device_t' | mdb -k
mdb: failed to perform walk: unknown walk name
# zfs set sharenfs=rw,anon=0 nippy
#  echo '::walk Device_entry_cache | ::print struct rfs4_dbe data | ::print mds_device_t' | mdb -k

We can see that once the share is enabled, we can walk the structures. We can redo the mdsadm command:

# mdsadm -o add -t auth -a ip=10.1.233.117
adding: IP Addr - 10.1.233.117
# echo '::walk Device_entry_cache | ::print struct rfs4_dbe data | ::print mds_device_t' | mdb -k

What is wrong now? We need to enable the ds:

# dservadm enable

And:

# echo '::walk Device_entry_cache | ::print struct rfs4_dbe data | ::print mds_device_t' | mdb -k
{
    dbe = 0xffffff02f4156f08
    dev_addr = {
        na_r_netid = 0xffffff02f61bfc80 "tcp"
        na_r_addr = 0xffffff02efde8a88 "10.1.233.117.147.49"
    }
    dev_flags = 0x3
    dev_infop = 0xffffff02f4157f78
    dev_list_next = {
        list_next = 0xffffff02f4157fb8
        list_prev = 0xffffff02f4157fb8
    }
}