On Sun, 4 May 2014, L.M.J wrote:

 5) I'm not a mdadm expert, after a couple of minutes on Google, I've found a command who looked quite
 good to me. I made a new partition on sdb (sdb1) and :

Where did you find this? 
https://raid.wiki.kernel.org/index.php/RAID_Recovery explicitly states not 
to do that unless as a last last resort.

It also has some hints about what you can do next (the permutate_array.pl 
script).

-- 
Mikael Abrahamsson    email: swmike@swm.pp.se