I've done the following and at first I didn't mail in case it was a weird vmware bug but it does exactly the same thing on real hardware.
Someone mentioned fairly recently in 'equivalent of Linux "mount -o bind"' which should interest a recent poster a little, that you could use /dev/wd* directly with vnconfig which seemed faster and easier, it is not in the man page so maybe there is something lucky or hit and miss when it works and so hopefully someone will know straight away and make me look stupid as to why I'm at a loss with what I've found. I've used wd1c as an immovable object in disklabel which is working but figured I should atleast report the following in case it isn't expected. Should I use an image file on wd1a instead of /dev/wd1c? Drives zeroed /sbin/vnconfig -ck svnd0 /dev/wd1c /sbin/disklabel -E svnd0 /sbin/newfs /dev/rsvnd0a /sbin/newfs /dev/rsvnd0d /sbin/vnconfig -ck svnd1 /dev/wd0l /sbin/disklabel -E svnd1 /sbin/newfs /dev/rsvnd1a reboot, I guess disklabel -c would do the same wd0l and svnd1 work fine (disklabels visible and work fine) I have to recreate the disklabel for wd1 and svnd0 after which it works fine untill the next reboot (data accessed). p.s. I am using bioctl for some things but here they are small and currently non performance critical, so I went for blowfish.