USB drives that are formatted as a EFI System Partition don’t work in Windows 7 and are unable to be managed using the Disk Management tool. This can leave you with a USB drive that cannot be completely used, for example a 16 GB drive with only a 2.5 GB partition that can’t be extended into the unallocated space.
The steps below show how to use the DISKPART command line tool to reformat the USB drive. You will need local administrator access on the computer to follow these steps. The process will involve wiping the USB drive – back up before progressing.
- On your keyboard, press the Windows button + R
- type DISKPART and click ‘OK’
- Click ‘Yes’ if prompted by the User Access Control
- DISKPART will open in a command prompt window
- Type list disk and hit enter
- You will need to identify your USB drive by size, in this case I can see it is disk 2
- Type select disk 2 (where 2 is the number from the previous step)
- The command prompt will respond by saying “Disk 2 is now the selected disk”
- Now enter the following commands
attributes disk clear readonly clean convert mbr create partition primary select part 1 format fs=fat32 quick assign letter (letter) list volume
- Type exit and hit enter to close the window.
- You drive will now be reformatting using the full capacity as FAT32