Windows Won't Recognize 3TB HDD, Despite GPT

[Boebe]

I am running Windows 7 Professional 64 bit with a UEFI enabled motherboard. I have a Toshiba 3TB hard drive in an external case that I planned to use to backup my internal hard drive. When I first formatted it, I chose GUID Partition Table and was able to see all the available space. However, now I've plugged it into my computer via USB and I cannot see the drive under My Computer. I can eject it from the tray, where it's called "USB to ATA/ATAPI Bridge." I can see it in Disk Management but it is listed as having 2097024 MB capacity, with the partition style as GPT. If I try to create a new simple volume I cannot create a partition larger than 2097022 MB. I understand that a drive's capacity is a bit below its nominal value, but I cannot believe that a 3TB drive actually has less than 2.1TB capacity. I have an identical drive as my internal drive, and it is listed as having about 2.7TB capacity.

How can I format this drive so that I can use it as a backup and have access to its full storage capacity?

 

[popatim]

It sounds like you need an external usb adapter that really supports drives larger that 2.2TB.

 

[Boebe]

It sounds like you need an external usb adapter that really supports drives larger that 2.2TB.

Do you mean the hard drive enclosure I'm using? Because it was advertised as being capable of handling 3TB drives, and I used it when I initially formatted the drive. As I mentioned, when I initially formatted it I was able to see its full capacity.

 

[Boebe]

I think I've resolved it. The case came with an eSATA connector and my motherboard has a slot for that, so I connected it that way and now I can see the full capacity. I don't know why the USB connection didn't work.

 

[popatim]

...However, now I've plugged it into my computer via USB and I cannot see the drive under My Computer.

How was it plugged in before, when you were able to format it then ?