The problem that you had is rare, it happens when the failed hard drive corrupts the data on the RAID structure that it is also on all of the hard drives.
Think it like this, the failed hard drive lost also the structure on it, but the structure on a second hard drive is corrupted so the RAID controller does not know how to rebuild the array and this is why it shows as failed.
Unfortunately there are no Intel(R) tools to try to recover this data, but as a personal advise, some software's available on the Internet will be able to recover some information, it will be a good idea to try them.
Great... at least the only real data loss is the movies i brought online to my network. That can be redone. Everything of a critical nature has its own backup to an external drive cage.