I posted this problem in another forum with no luck, perhaps some of you can help:

 I have an EX-475 with 2 external USB drives (400 and 500 GBs). I recently installed an additional 1 TB internal drive and would like to remove the 400 GB from the pool. I used the Remove Drive Wizard but it ends with an error message saying not all files could be copied and it is not removed from the pool. However the USB drive I'm trying to remove reports 0% usage and it looks as if all of the data has been moved to the new internal drive. I have retried the wizard several times with the same results.

My next move may be to remote into the server, reformat the drive in question and again try the wizard. Since I have duplication turned off and I do not use the MSS as backup to my other PCs I don't believe I am risking much. However, since I have almost 2 TBs of data that I don't want to reload, I will continue to investigate all options before making that move.

Anybody have a better plan?