About 6 months ago I picked up a 6TB HGST Deskstar NAS drive on sale to use as my Time Machine Drive after I filled my current 3TB WD Red drive. This morning I finally swapped the drives and it's telling me the drive is unreadable. When I use Disk Utility, the partition button is greyed out. This drive is attached to my Mac Pro via USB. Can anyone tell me what's going on and how to fix? Thanks!