I format a GPT external disk on a Windows 7. It has 4 Tb (3761 Gb prec.) capacity. Then I copy the data.
Everything goes perfectly untill one day without having changed any settings, the drive isn't recognised anymore.
The same on xp x64 bit, Vista, many other options... I'm really exhausted...
I used a LACIE big and a fantec set in combination with 2 HD (2Tb).
So it is not the HW....
Have you rebooted? I had a drive go into "RAW" mode and it would not show up with a drive letter in Windows Explorer. Other drives plugged into the same USB port worked fine. When I rebooted the problem went away.
I tried another time yesterday (your today ;-) I think) but still gives me one drive at 8Gb not allocated, the other one not recognized.
I repeated the procedure for both the 4 tb drives: I formatted in GPT mode and get two 3761,... Gb drives.
I formatted in NTFS mode and at present it is copying the huge amount of files...
I think the problem will not represent again if I use the USB plugs. This way however it will cost 22 hours for the main copying process instead of 7,8 hours with e-sata plugs. Thank you anyway for your answer.