Here is my issue. The drive states its almost full. 415GB used of a 500GB HD. I am running Sierra on an iMac. When I go into manage it states the system is using all of the space and its grayed out. I do not know how to free up this space. I have run disk utilities thinking maybe the drive is corrupt, but the problem persists. I have 6 of these identical iMacs and this s the only one with this issue. Any help would be much appreciated. Thank you!