With triple-mirrored vdevs, I'm really not sure why I can't re-import anyway. There was also a read cache vdev, but that is no longer connected, though that doesn't seem to be the issue. I've all but given up, but maybe someone else can point me in a new direction.
Here's what I see:
# zpool import -o ro -f -m
pool: tank
id: 15181238712954073451
state: UNAVAIL
status: One or more devices were being resilvered.
action: The pool cannot be imported due to damaged devices or data.
config:
tank UNAVAIL missing device
mirror-0 ONLINE
powervault-16f4fc ONLINE
powervault-16f268 ONLINE
powervault-b8e400 ONLINE
mirror-1 ONLINE
powervault-b89ddc ONLINE
powervault-b90178 ONLINE
powervault-16f134 ONLINE
mirror-2 ONLINE
powervault-b91060 ONLINE
powervault-b92ad8 ONLINE
powervault-d9de69 ONLINE
mirror-3 ONLINE
powervault-1703ec ONLINE
powervault-b8d670 ONLINE
powervault-b90144 ONLINE
mirror-4 ONLINE
powervault-489817 ONLINE
powervault-b915b0 ONLINE
powervault-b73838 ONLINE
mirror-5 ONLINE
powervault-b9114c ONLINE
powervault-b92b30 ONLINE
powervault-16cbd0 ONLINE
mirror-6 DEGRADED
powervault-b90f70 ONLINE
powervault-b915c8 ONLINE
11183873526684940444 UNAVAIL
mirror-7 ONLINE
powervault-b92050 ONLINE
powervault-b90d4c ONLINE
powervault-b3ec0c ONLINE
mirror-8 ONLINE
powervault-170a68 ONLINE
powervault-16f00c ONLINE
powervault-b916a0 ONLINE
mirror-9 ONLINE
powervault-1700c4 ONLINE
powervault-b8fa5c ONLINE
powervault-b91ad4 ONLINE
mirror-10 DEGRADED
12935469030838970131 UNAVAIL
powervault-b915d0 ONLINE
powervault-b90f04 ONLINE
