Issue: AMD RaidXpert Service gives an Raid 1 (or 5, as reported in other forum) array "error" stating a single disk failure. One of the two drives (or may be more in your case, but if that's the case you are beyond screwed) in the Raid 1 array becomes a JBOD standalone drive, basically detached from the array for whatever reason. The drive is still listed as healthy and SMART scan does not show any issue either. It is simply "assigned as JBOD" under "Logical Drive View" in RaidXpert.
OR, you really have a dead drive, and you have inserted a new drive. But even after you have initialized it, the Rebuild tab is still greyed out.
The "reasonable" procedure, by intuition, since there is no manual, is to start RaidXpert in the browser (username and password by default are both "admin"), go to the "Logical Drive View" and do a "Rebuild". The problem is, the "Rebuild" tab is greyed out and unusable. You can only see the failed array listed as "Critical", one of the two drives (in my case) is still mounted as part of the Raid 1 array, but the other drive is now JBOD. This can also happen if the drive is new. It is simply "assigned" as a JBOD. And the "Rebuild" tab is still greyed out.
You basically cannot rebuild.
This problem has been reported on many forums and no one has provided a step-by-step solution. The AMD Help with the software is inaccurate and unhelpful.