To summarize: I have a mirrored #ZFS pool which crashes both FreeBSD kernel and #OpenZFS when trying to import (both disks and each separately).
The disks are old but fine, no IO errors (I have dd/raw images of both disks), last daily scrubs were fine.
Ideas anyone? @robn perhaps?
Related to my post here: https://forums.freebsd.org/threads/kernel-panic-with-zfs-destroy-on-snapshot.100660/