Root mount waiting for: usbus1
Trying to mount root from ufs:/dev/ad4s1a
ROOT MOUNT ERROR:
If you have invalid mount options, reboot, and first try the following from the loader prompt:

     set vfs.root.mountfrom.options=rw

and then remove invalid mount options from /etc/fstab.

Loader variables:
vfs.root.mountfrom=ufs:/dev/ad4s1a
vfs.root.mountfrom.options=rw

mount>