ZFS: cannot import zroot: I/O error

Hello,

I'm running a FreeBSD 13.1-RELENG-p1 zroot-based guest in a VirtualBox 4.1.24/26 (do not know
exactly). The host is a special system based on Linux und VirtualBox and I have no chances to
configure the VBox.

Somehow the VBox crashed and hung up the complete computer, so I had to cold start it after
approx. 30 minutes of waiting. After that, rhe virtual drive and its ZFS filesystem was
wrecked, shwing a stream of 

zio_read error: 5
ZFS: i/o error - all block copies unavailable

After a quick search I found some advices howto try fixing, last an longest one was 

zpool import -fFX -N -R /alternate/path zroot

which took approx 20 minutes - with no success.

There are some valuable data on the partition, which are all backed up, but it would take its
time to restore everything, so I'd like to ask whether there is any cance to "repair" the
mysterious damage.

I'm able to boot off from an USB flash drive ...

Kind regards

oh



-- 
O. Hartmann