In many forums and wikis the recommended way of changing the uuid of a fat partition involves dd and a hex editor.
However the easy way is to use mtools. Let's suppose we want to change the UUID of a fat partition on /dev/sda1.
As a first step we have a look at the UUIDs of the different file systems:
> blkid
/dev/sda1: SEC_TYPE="msdos" LABEL="boot" UUID="4059-33BB" TYPE="vfat"
…
This tells us that /dev/sda1 has the UUID 4059-33BB. Not that this number is called “serial number” in the language of FAT systems.
Now we install mtools. For Debian based systems like Ubuntu or raspbian we type> sudo apt-get install mtools
After installing mtools we have to configure the drive letters. As root you have to edit /etc/mtools.conf.>sudo nano /etc/mtools.conf
We add the linedrive d: file="/dev/sda1" exclusive
to that file, save and exit the editor. Now, we can check the this line using> mdir d:
If you get an error message about inconsistencies in the block sizes, you can silence it with the line:> echo mtools_skip_check=1 > ~/.mtoolsrc
After checking the mdir command again, we can change the serial number of the partition using> mlabel -n d:
That's it. You can verify your results using the command blkid.
Changing the volume label is an exercise that is left to the reader. As a hint the following commands give you access to the corresponding information:> mlabel --help
> man mlabel
> info mtools