An error occurred during synchronization

All the other errors show zero.  Only the ATA errors.  I find it hard to believe that 2 of 4 WD RED 3TB hard drives failed simultaneously after only 2 years of light use.  This NAS stores only my video collection and doesn't see much IO.  Also, RAIDar and the web admin page always showed the drive in good status (meaning the device status is showing "Healty" on the System page which shows healthy even as we speak even though i can not access any drives).  There was no warning.

What does "Disk: Disk in channel 2 (internal) changed state frmo ONLINE to FAILED" mean?  This happened at exactly the same time for channels 2 & 3.  I find it more likely that it's a failure of the NAS board that communicates with the drives.  Also, why are drives 1 & 4 showing as Inactive? Is this just because drive 2 & 3 failing simultaneously knocked out the RIAD 5 array?  It's not very comforting.  Anything that can be done to troubleshoot repair this?  I feel like right now, the NAS has had a complete failure and i don't even know why which is the most frustrating part.

Schwizer