I had actually tried this last night. It won;t kill it. From what I read if a status is D during the process it will remain that way forever. Its impossible to kill a process with a D status.
What I then tried was just pulling the USB. That of course solved the issue and then I tried again. This time I used the -v so I can see where in the copying it stopped. I tried again. But what I noticed is that this time it couldn;t have stopped in the same place, since the amount of files copies to the USB is far less. This AM I tried a third time. First I went into Ubtunu and formatted the partition here as FAT32 to test that out. I did a copy again but it again froze. This time even smaller amount of files copied before it failed. Since the amount of files transferred keeps shrinking could this be a memory issue? USB drive is 3TB but figure the size of the drive shouldn't matter. Thoughts?