Raid 1 broken

Hello
I would like to have a working Raid 1 in ext4.
I got 2 new 2to disks in the raid and it was working fine until now.
Since it crash i have to rebuilt it manually but it's always bad at reboot.

root@data:~# mdadm --assemble --force /dev/md0 /dev/sda
# mdadm: /dev/md0 has been started with 1 drive (out of 2).


root@data:~# sudo mdadm --manage /dev/md0 --add /dev/sdb
#mdadm: re-added /dev/sdb


# this do nothing
sudo mdadm --monitor --daemonise /dev/md0

Then, i have to mount the /dev/md0 into the file system into /media/Raid to get it in share. The OMV ui see the subfolder, but afp, ftp or samba are unable to share them…

I like the Omv functionalities, i was before on Ubuntu server that i stop for mdadm same problem.
In fact when all is good, something happend in mdadm raid and i always need to rebuild all…

Is there a way to be more secure with data ?

Thanks a lot for your read

Xavier, from France.