mountroot

[Dick Hoogendijk]

I'm a little desperade. I installed a mirrored ZFS freebsd system in a 
VM the other day and all went well. Now I did the same procedure on a 
real systrem with two drives and I can't get the system to boot 
properly. Everytime it halts at the mountroot prompt.
If I manually put zfs:zroot at the prompt the system boots to the login 
screen.
I checked the /etc/rc.conf and the /boot/loader.conf for syntax errors 
but all seems well. What on earth can be the cause of this behaviour? 
What do I check? Help?