Raid 5 questions

[Aron Szabo]

  Hi!

I have a raid problem ... one of the subdisk is missing and i can't 
mount my partition.

FreeBSD testhost 8.1-RELEASE FreeBSD 8.1-RELEASE #0: Mon Jul 19 02:36:49 
UTC 2010     root at mason.cse.buffalo.edu:/usr/obj/usr/src/sys/GENERIC  amd64

# gvinum printconfig
# Vinum configuration of aladar.mzperx.hu, saved at Tue Oct  5 13:06:57 2010
drive disk1 device /dev/ad4s2
drive disk2 device /dev/ad6s2
drive disk3 device /dev/ad8s2
volume user
plex name user.p0 org raid5 512s vol user
sd name user.p0.s1 drive disk2 len 1869638656s driveoffset 265s plex 
user.p0 plexoffset 512s
sd name user.p0.s2 drive disk3 len 1869638656s driveoffset 265s plex 
user.p0 plexoffset 1024s

# gvinum l
3 drives:
D disk1                 State: up    /dev/ad4s2    A: 912909/912909 MB 
(100%)
D disk2                 State: up    /dev/ad6s2    A: 0/912909 MB (0%)
D disk3                 State: up    /dev/ad8s2    A: 0/912909 MB (0%)

1 volume:
V user                  State: up    Plexes:       1    Size:        891 GB

1 plex:
P user.p0            R5 State: up    Subdisks:     2    Size:        891 GB

2 subdisks:
S user.p0.s1            State: up    D: disk2        Size:        891 GB
S user.p0.s2            State: up    D: disk3        Size:        891 GB


How can I re-add  my disk ?

Thanks!

Aron