I just got two new 3TB seagate drives for my Mac Pro at work (4,1- Snow Leopard) that disk utility will not format. My steps: -Installed in drive bays 3 and 4 -reboot, get message that computer can't read drive, click initialize to open disk utility -choose erase tab, Mac OS Extended (Journaled), name and click Erase -confirm in pop-up (which notes that disk is unformatted) -Almost immediately get error pop up: "Disk Erase failed with the error: Could not unmount disk" I should note I get the same error trying to partition rather than erase (for 1 partition, Mac OS Extended (Journaled), set to GUID partition map) Any ideas? I am assuming that Snow Leopard does support 3TB drives, right? And that disk utility can format them (without 2.2TB limit)? Thanks!