While I was backing up my files from my DNS-323 (FW version 1.09) with dual 2TB WD Caviar Greens onto a USB drive, one of the WD drives failed in the middle of the backup. About one-half of the files got transferred. I went to recover the other files from the still functional drive, when I realized that the functional drive had NO FILES on it from before September, 2013. It was as though this drive were frozen in time at some date in September, with some of my files that I had been actively using and updating frozen in time as of a year ago. I have tried several methods to recover files from the functional drive (Ubuntu, R-Studio, Power Data Recovery) and NONE of these can see any files on that drive from before September, 2013. It is a catastrophic loss of data. (I know I'll get flamed for waiting so long to do a backup...)
Though I don't have much hope of recovering the missing files, this is the strangest problem I've ever seen. The only thing I can think of is that some FIRMWARE bug caused one of the two drives to be suspended as of September 2013, while the OTHER drive in the RAID 1 was fully functional until it died during the backup. I KNOW that the DNS-323 was allowing full access to all files at the time of the WD's death, because I have the first half of the files backed up to the USB drive, and there are files on there as recent as the day of the backup.
Any theories would be appreciated!