I installed a 3TB drive in my WindowsXP64 machine last year. I was having problems seeing all 3TB. I ended up using GPT for the drive and made a 2TB and 1TB partition and things were fine.
I'm moving to a Windows7-64 machine now. To my dismay, when i moved the GPT drive into the new machine, Windows7 will not read it and immediately says "This Drive Must Be Formatted". This is driving me crazy because I was trying to avoid large copy sessions across the network (old computer to new computer) so I moved all my inportant stuff to this 3TB drive with plans to just physically transfer the drive. But now Win7 can't seem to read it.
From everything i've read, it seems Windows7 should have no problem with GPT. Anybody have any idea what's going on and how to get around it?
Probably gdisk will tell you that your gpt table is damaged. See if any of the suggested fixes work for you. I had no luck so just reformatted and moved everything back to the drive; if you don't have backups you may have to pay a specialist.
I'm not sure what caused the gpt table corruption but I suspect it may have had something to do with HD Tune or some gpt-unaware program writing to the wrong part of the drive.
EDIT: You may want to set up an RMA. My drive just became corrupt for the 3rd time while doing a simple Windows file copy. SMART shows no errors of any kind and nothing else is writing to the drive. I'm thinking these are from a bad batch.