Disk Space Take 2

Hey All, I posted about this last week but this is not 100% related. My script that copies files to my NAS (Mycloud Ex2) is telling me the disk is full. I have two disks in a raid 1 and the console tells me I have 1.29TB free and I am trying to copy less than that. It was pointed out that it could be space left in the volume I am copying to itself but I can’t find a way to (nor have I) limit the space in a volume. What am I missing in getting more use of my disk space here and how can I tell if the volumes are “limited” somehow? Thank you! Chris