https://serverfault.com/questions/765778/clonezilla-restore-mbr-disk-to-4tb-disk-convert-to-gpt-linux-not-windows

Converting the MBR to GPT on the OS/boot volume


edited Mar 26, 2016 at 1:15
emmdee

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Ensure you have a backup!!!!

 1. Boot into the system, the disk is currently MBR so it's 2TB max
    
 2. Run gdisk <disk>
    example: gdisk /dev/sda
    
 3. gdisk will give you a warning that it's MBR and will automatically
    conver to GPT. Type w and press enter. Confirm the write operation
    
 4. Go back into gdisk (like in step 2 above)
    
 5. Type p to print your partition table, the first partition should
    start on sector 2048 (this is default setup, if yours is different
    the rest of the steps won't be exact for you)

 6. Type n for a new partition.

 7. When prompted for first sector, choose the lowest number you can
    (which is probably 34) last sector is 2047 in my case. (right
    before the start of primary partition) -- Essentially start: 34,
    end: 2047.

 8, When prompted for the type, choose ef02

 9. p to verify the new partition layout

10. w to write changes

11. At the shell: sudo partprobe ignore the warning about the new
    partition created

12. At the shell: grub2-install <disk>
    example: grub2-install /dev/sda

13. Reboot, you should be good to go.

14. Use gparted or any other partition utility to expand over the now
    available free space. I personally booted to Ubuntu Live CD and
    used gparted for easy partition growth.

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