GELI Encrypted ZFS root/boot on a mirror: "Failed to read pad2 area of primary vdev"

[John Kozubik]

Friends,

I am using sysinstall from 12.0-RELEASE to create a ZFS root to boot from.

I have chosen to create a mirror, used the default GPT partition type, and 
enabled GELI encryption.  I set a passphrase for GELI.

sysinstall completed normally.

Upon booting, I see:


GELI Passphrase for disk0p3:

(entered via keyboard)

Calculating GELI Decryption Key for disk0p3: xxx iterations...
Calculating GELI Decryption Key for disk1p3: yyy iterations...
Failed to read pad2 area of primary vdev

Can't find /boot/loader


...


I have repeated this install *without* any GELI encryption and the system 
boots and operates as expected.

What am I seeing here ?


Thanks.