Raid does not start automatically

Hello,


my debian 4.0 box works fine with linux software-raid. today, I have
tested the possibilities of the mdadm tool.
I have removed a disc, I have added a disc and finaly I have stoped a
RAID-device.

After the reboot, I have created a RAID-device with the previously used
partion.

mdadm --create /dev/md8 --raid-devices=2 --level=1 /dev/sda10 missing

mdadm: /dev/sda10 appears to be part of a raid array:
    level=raid1 devices=2 ctime=Tue Dec 18 17:42:58 2007
Continue creating array? y
mdadm: array /dev/md8 started.



After the next reboot, the  device does not start. why ?

can anyone help me ?


Tino