Cause we are using both the some version for the pxeboot as for the normal
boot, there is a caveat in which root system to load first.
as you can see in /usr/src/sys/kern/vfs_mount.c
1381     /*
1382      * Try to use the value read by the loader from /etc/fstab, or
1383      * supplied via some other means.  This is the preferred
1384      * mechanism.
1385      */
1386     cp = getenv("vfs.root.mountfrom");
1387     if (cp != NULL) {
1388         error = vfs_mountroot_try(cp);
1389         freeenv(cp);
1390         if (!error)
1391             return;
1392     }

it first try to check vfs.root.mountfrom and then it checkes /etc/fstab

if we are booting from pxeboot /dev/md0 needs to be rootfs,
but when using normal disk /dev/ad0a needs to be rootfs

Fix:
node/boot/loader.conf.local includes a line
vfs.root.mountfrom="/dev/md0", which isn't included into the images (eq when
using disk just the normal /etc/fstab is followed)


Cool isn't it ;-)
Rick van der Zwet <rick@wirelessleiden.nl>