I've been having strange behavior with 3 TB 3.5" SATA hard drives. There's one that I was using with a Goflex dock. I was able to format it as a 3TB drive and use it without problems. Then I installed it inside an early Mac Pro (1,1) and DiskUtility didn't recognized the 3TB format. However, I was able to put a new 3TB drive inside the MP and format it that way, and then clone the data from the other 3TB drive. This same issue has been happening with a Datatale 4 bay external FW enclosure I have; when I put one of the 3TB drives I've been using inside, they don't get recognized as 3TB formatted drives...but I am able to format them and use them as 3TB if I start from scratch. In other words, it seems like whenever I move a drive from one device (dock, Mac Pro, external enclosure), it is no longer recognized (I get a dialog to initialize, and DiskUtility see the drives as unformatted). But if I format the disk in the new device, I'm able to format and clone the data without issue. I'm currently using a 2011 MBP; I just got rid of the MP. Does anyone have any idea what's going on, and how to avoid this?