Changing a Volume's "Device / Media Name" I know a Mac volume can be renamed... obviously.

But if you look at the output of diskutil you will see that a volume also has a "device name" that corresponds to the name it was given when it was formatted:

diskutil info /dev/disk0s1 | grep 'Media Name'


Running it on your root volume you will probably get "Macintosh HD" (or else something like "Untitled 1" if that's how you left it when formatting in Disk Utility). It seems this doesn't change when you rename the volume after the fact.

Why do these different names for the same volume exist?

Does anything even refer to this hidden name?

Can it be changed?
The "Device / Media Name" is the partition label from the disk's partition map (GPT - GUID Partition Table).

To change the label for a volume, you'll need to use the terminal.


Get the disk number of interest: diskutil list
Show the current partition labels (note the index of the entry you would like to change):

sudo gpt show -l /dev/disk0


(Note: replace disk0 with the disk number from step 1)
Eject the disk from the Finder (or use the unmount terminal command if you'd like). If you don't do this, you may get a Resource busy error message during the following step.
Change the partition label as desired:

sudo gpt label -i 2 -l "My New Partition Label" /dev/rdisk0


(Note: replace the "0" in rdisk0 with the disk number from step 1 and replace the "2" with the index number from step 2)
(optional) Verify the changes by either repeating step 2 or typing: diskutil info disk0s2


For more information see the manual page for the gpt command-line tool: man gpt