I took the hdd out of my external computer to transfer a large # of files (over 1TB worth) and to use the full 3tb I made it a GPT Partition. Now since I want it back in the normal enclosure the computer "sees" it, in the device manager or a partition manager, but they say it is a MBR and needs formatted? I am assuming it has to to with the sata to usb converter in with the enclosure. I just would like to see the 'old' record with the gpt partition of 3TB's.
Maybe you should start from the beginning and give more information... IF it had an MBR, it WAS a system drive. If you changed the partition type, the old data may no longer be accessible. Not all Partition types are supported by all Operating Systems. If you are being prompted to format the drive, then the formatting is not recognized by the System.
Post back here with some details, and hopefully we can get you taken care of.
I think I had figured it out, the device wanted to be the main controller for the card, so when it had a different partition table as the drive, it wanted to read as non-partitioned, but when both were the same, the device was recognized. But anyway, I just added the drive to my simple ubuntu server since my router apparently has issues with 2TB+ (some people had success but some don't)