Re: removing GELI from a zfs-on-root system

Technically, if the user can find a space (can even be a md device if 
they feel lucky but I don't really recommend doing it that way) as large 
as the root pool's device, they could accomplish the goal by attaching 
the new device as a mirror to the old root device's mirror, remove old 
device and do the same dance again in reverse order.

Assuming the pool is called "mybootpool", old device is "mygelidevice" 
and new device is "newdisk":

zpool attach mybootpool /dev/mygelidevice /dev/newdisk

Then wait for the resilvering to be done.  I would do a scrub to verify 
that everything is good here:

zpool scrub mybootpool

Run "zpool status mybootpool 10" until scrub is finished with no error.

Then:

zpool detach mybootpool /dev/mygelidevice

Now destroy the GELI device, repeat the steps above but swap the two 
devices.

Cheers,