Remove ‘EFI’ & Other Partitions on a USB Flash Drive Using Windows 8 (Created by ‘dd’)

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In GNU/Linux, you can create a bootable USB flash drive using an ISO disc image of another distribution, by using the command-line. The command that is used to create that is called ‘dd’.

By default, almost all USB flash drives use a common partition layout (which of course can be changed) that consists of a single, primary partition occupying the whole space. However, when you use ‘dd’ on an USB flash drive, it will destroy this layout and will create a new partition layout.

It will create a partition that is big enough to hold the data of that ISO file, followed by another special partition called ‘EFI System Partition’ that stores files related to booting etc and finally, the remaining space (if any) of the USB flash drive will be hold in, as an ‘Unallocated area’.

'Disk manager' in Windows 8 showing 'EFI' and other partitions

The thing is, other operating systems like Windows 8 will only recognize the ‘EFI System Partition’ (which is usually around 2-3MB) and the rest of the ‘free space’ will be unusable!. Even other advanced tools like the ‘disk manager’ in Windows, though it properly recognizes the partition layout, won’t let you create a partition on the remaining ‘free space’ and use that space either.

Windows 8 showing the 'EFI' partition of a USB flash drive

Not only in Windows, but some tools in GNU/Linux have also failed while letting me create a partition on this ‘unallocated area’ as well.

I personally don’t like this approach used by ‘dd’ (though it might have some advantageous), as it creates unnecessary complications, because you can still create a bootable USB flash drive, without having to repartition it this way, thus you will be able use it as usual (reformat, delete or add files etc).

Nevertheless, if you did not know this at the time you used ‘dd’ and looking for a way to get rid of it using Windows 8, then please follow the below steps. Not only by ‘dd’, you can use these instructions for getting rid of ‘EFI’ partitions created by other tools too.

Note: Before proceeding, please be aware that, this will destroy all the data on the drive!.

Step 1:

Press the ‘Windows key’ on your Keyboard and then simply type the below command.

cmd

Step 2:

Then Windows 8 will locate the ‘cmd’ application. Now, as shown below, right click on its icon and then from the options that will be listed at the bottom of the screen, select ‘Run as Administrator’.

Running 'cmd' as the administrator in Windows 8

When asked, click ‘Yes’ to the next message.

Step 3:

This will open ‘cmd’ with administrative privileges. Once it is opened, type the below command on its window (make sure the USB drive is attached).

diskpart

Then wait for few seconds, until the command prompt changes into ‘DISKPART>’.

Step 4:

Now enter the below command.

list disk

This command, as shown below, will give you a list of all the disk drives that are currently attached to your computer (USB, IDE, SATA etc).

Using 'diskpart' for listing attached disc drives

Now have a careful look at its output and make a note of the disk drive number of the USB flash disk that we need to restore to its original partition layout (in this instance it is ‘Disk 1’).

Step 5:

Once you know the disk number, simply replace the ‘Disk 1’ (unlike GNU/Linux, Windows is not case-sensitive, so you should be able to use ‘disk 1’ as well) part of the below command with your disk’s given name and execute it.

select Disk 1

When you issue this command, it will give you an output saying that, that particular disk is now selected (shown below).

Using 'diskpart' to select a disk

Step 6:

Now to delete the partition layout of this disk, enter the below command (this will erase the entire disk!, so make sure the entered disk name is correct!).

clean

If you get an error saying that somehow ‘diskpart’ was unable to do it (it happens sometimes), then try the ‘clean’ command again. If everything goes accordingly, then you should see the message ‘DiskPart’ succeed in cleaning the disk’.

Successfully erasing the partition layout using 'diskpart'

Step 7:

Now all we have to do is to create the standard partition layout that is used in USB flash drives (a single, primary partition, occupying the whole space). For that, enter the below command.

create partition primary

If it was successfully created, you should see a message saying ‘DiskPart succeeded in creating the specified partition’.

Creating a primary partiton on the USB flash drive using 'diskpart'

Step 8:

Now open ‘My Computer’, double click on the USB flash drive’s icon, and Windows 8 will ask whether you’d like to format the drive or not.

Windows 8 asking for the permission to format the usb flash drive partition created using 'diskpart'

Then make your selections from the ‘format disk’ window that you get next (when unsure, use the default settings), once done, click on the ‘Format’ button.

That’s it, now you should have restored your USB flash drive to its original partition layout and can start using it as usual. Good luck.

Credits: Some information via ‘Winability.com’.

64 thoughts on “Remove ‘EFI’ & Other Partitions on a USB Flash Drive Using Windows 8 (Created by ‘dd’)”

  1. It seems that I have an entirely new beastie on my hands… a USB stick with only one partition, but somehow a virtualized CD drive is installed on it!

    Trust me, I have attacked this thing six ways to Sunday. There is only one FAT partition, diskpart sees only one drive, and yet even after clearing it out with diskpart, linux partitioners, Mac partitioners and even doing zero-fill wipes with boot utilities, this drive still has a virtual CD-ROM on it.

    I have to take my hat off to those who designed this drive… because I have in my hand a USB drive that has got a virtual CD-ROM, but without that virtual CD-ROM appearing anywhere on the drive itself!

    Reply

  3. What a brilliant article I’ve ever had learnt…. Thank you so much!!!! This one saved my life… Thanks a lot! 10 stars for you!

    Reply

  7. Thanks for this information. It worked very well. I had partitions the usb drive for a mac and when I finished my work with it, I wanted to convert it back to a ntfs partition. I had no difficulty in following the instructions.

    Reply

  8. Thanks! worked great. I had a USB stick that had been previously used to boot a linux distro and windows only recognized a small portion of its capacity. Followed this how to and now the USB stick is restored to its full capacity.

    Reply

  9. Thanks, I don’t know how it managed to get partitioned, but this completely and easily restored by USB to it original state. Thank you so much

    Reply

  10. Thank you.

    I had this problem – found your post – your steps were clear, concise and exact.

    Thank you again. Problem solved, and I learned something today.

    Reply

  28. Hi
    I have microSD HC card.
    When I try to make format this card Win7 showing that “Win7 couldn’t finish format drive” In settings of card i can’t do nothing :/
    What to do ? Can U help ?

    Reply

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