Where is reserved extra space in Startup Disk Creator 16.04?

Solution 1:

I'll answering your last question first. The newer live-usb ISO's are hybrids that work for both MBR and GPT systems. gparted cannot read these after Startup Disk Creator has burned the ISO to the USB flash drive. Rather than taking your USB to another computer to reformat it you can use dd (Data Destroyer, real name Data Duplicator):

sudo dd if=/dev/zero of=/dev/sdX bs=512 count=1

Change sdX to sdd, sde, or whatever your USB drive letter is.

Use dd with great caution!

As you discovered Ubuntu 16.04 Startup Disk Creator no longer provides an option for persistence storage for a Live Boot USB Flash Drive. But mkusb does provide this feature and it works well even for creating a pre-release Ubuntu 18.04 Live Boot USB.

For more about mkusb details read about it here.