Can anyone explain to me how to deal with the fact that there are at least two different volume labels for FAT systems on Usb Sticks? One is displayed by blkid and dosfslabel, while the other shows up in gparted and cfdisk. The second one is the one displayed in Windows7 under the disk's properties. The fact that Linux is not consistent means that any time I need to use a volume label I can't be sure which one is required or how to create it.

I found where the first label is stored: it is in the first sector of the partition, just where it was on floppy disks many years ago. However, I haven't been able to locate the second label as yet.

Hi there,

I'm not sure, but I think that's a misunderstanding on your side. FAT file systems can have a volume label (but that's optional), and they have a volume serial number (which is mandatory). The volume serial number, introducewd with DOS 4.0, is a 32bit number chosen randomly when the file system is created. It's stored somewhere in the first 100 bytes of the partition's boot sector. Years ago, I used to know by heart where all that stuff is, but that useless knowledge has faded.

In my test case, dosfslabel and gparted display the same - the traditional DOS volume label which can be set and changed anytime, or an empty string if the partition has no volume label. However, gparted always displays the volume serial number, too.

That would be the volume serial number, I guess.

For all I know, Linux uses the DOS volume label if one is assigned, and the volume serial number if not.

That's only one place. It's also stored as a directory entry in the root directory with the "volume label" attribute set. Just like all DOS versions since 3.0 did it.

[X] Doc CPU

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Part of my confusion was caused by the fact that some of the Linux utilities use the volume serial number if there is no volume label. I have discovered a bug (reported here: URL="https://bugzilla.redhat.com/show_bug.cgi?id=1158101")
in the fatlabel utility. Apparently, fatlabel assumes that the first entry in the root directory is a volume label. If there is no volume label, or if a volume label is not the first entry, fatlabel still tries to interpret the first entry as a volume label, and overwrites the entry if asked to create or change the label.

Based on what I now know, I would strongly recommend avoiding the use of fatlabel to generate a volume label on anything other than a clean system, until this bug is patched.

Thanks for your help.