How to determine /dev/ad* from mount label

[Mark G.]

Hi,

I've tried the mount, tunefs and df manuals, and don't know
where to look next.

I am trying to find out what device, in terms of /dev/ad0s1a
and so on, is actually 'connected' to a label mounted file
system.  Here is my fstab (from PC-BSD, by the way):

# more /etc/fstab
# Device          Mountpoint   FStype      Options Dump Pass
/dev/label/rootfs0      /      ufs             rw,noatime      1       1
/dev/label/swap0        none   swap            sw              0       0
/dev/label/var0         /var   ufs             rw,noatime      1       1
/dev/label/usr0         /usr   ufs             rw,noatime      1       1
procfs                  /proc  procfs          rw              0       0
linprocfs               /compat/linux/proc linprocfs rw        0       0
tmpfs                   /tmp   tmpfs           rw,mode=1777    0       0

I just wanted to know if there was a utility to tell me
which actual device was mounted.  I also tried camcontrol devlist
and atacontrol list.  The latter allowed me to determine that
/dev/label/rootfs0 is ad2s1a based on the actual disk size
and a process of elimination.

Does anyone know a magic incantation to output this label->device
mapping?

Thanks
Mark

P.S. The latest FreeBSD 8 under PC-BSD is really quite good.
My thanks to everyone involved.  Picked up a copy at the
freebsdmall with the guide.  Excellent.