Currently Being ModeratedMar 22, 2013 8:18 AM (in response to studiogMTV)
What are you running the MDCs on? If Apple gear, did you enable Spotlight on the volume? If so, the mdutil processes hold on to the volume with a death grip, preventing eject of the volume. You can try to use launchctl to unload the mds processes but this works about 40% of the time. Otherwise, you need to reboot the machine and then eject the volume within the first ~3 minutes.
If you are on StorNext MDCs, then I am stumped as I have not seen this behavior.