problems using gmirror

[Tom Worster]

i've been trying to use the procedure described at 
http://www.onlamp.com/pub/a/bsd/2005/11/10/FreeBSD_Basics.html

i followed it to the letter. i'm using the install cd from from 
the freebsd 6.1-release iso.

my primary disk is on sata-0 which is /dev/ad4 on my dell poweredge
400sc.

in the label editor i used the "auto defauts" giving 5 slices for
 / swap /tmp /var /usr.

everything goes according to plan for page 1 of that article. but 
the machine does not reboot. it fails while:

Trying to mount root from ufs:/dev/mirror/gm0s1a

because that device doesn't exist. the computer hangs at the 
mountroot> prompt because of the keboard bug in 6.1-release. when 
i reboot in safe mode and enter ? to list geom managed disk 
devices i see only mirror mirror/gm0s1c mirror/gm0s1 mirror/gm0 
and all the ad4 devices. in other words: mirror/gm0s1a and the 
other three slices are not listed in /dev/mirror.

i've been through the install process about 5 times now carefully 
checking everything and i can see from ls /dev/mirror that the 
command:

gmirror label -v -b round-robin gm0 /dev/ad4

generates only the /dev/mirror/gm0s1c in /dev/mirrior, the other
four slices are not there.

any suggestions?

thanks
tom