raid1 recover

[Dmitriy Tochansky]

Hello!

I need some help about recover raid1. I have a raid ar0 with two disks. 
After first disk fail, I replaced it with new clean disk.
After boot I did:
# natacontrol addspare ar0 ad0
then
# natacontrol rebuild ar0

I type:

# natacontrol status ar0
and see raid in rebuild state. In a few seconds system hangs and I had 
to reboot it. Now I see:

# natacontrol status ar0
ar0: ATA RAID1 subdisks: DOWN ad1 status: DEGRADED

# natacontrol addspare ar0 ad0
natacontrol: ioctl(IOCATARAIDADDSPARE): Device busy

and finaly:
# natacontrol rebuild ar0
natacontrol: ioctl(IOCATARAIDREBUILD): Input/output error

Can someone point me to proper manual about how to recover failed disks 
and may be how to recover my current situation.

-- 
Dmitriy