Gosh i have the same issue now. Suddenly it was ejected randomly. Blinking Red LED. and it has strange sound.
I've tried to reversed plug or swap ports on both the duo or my macbook pro. If i'm not plugged it to my macbook pro, it sounds normal.
I'm so scared i might lose all 4TB projects on RAID 0 or worst, my macbook pro Thunderbolt ports was defective
At this moment i do not have spare TB cable. and projects are waiting to be sent
I attached 3 of My Book Studio Firewire daisy chained to the Duo using FW to TB, These drives are successfully mounted without issue. Only the Duo disappear from the system