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Wrong EFI System Partition GUID?

rated 0 times [ 11] [ 0] / answers: 1 / hits: 10387 / 1 Year ago, fri, february 17, 2023, 11:29:03

On a new GPT initialized disk (second PC disk) I created a FAT32 partition using gparted. I want to use it as an EFI System Partition so I flagged it as boot. After that I checked the UUID using the gparted “partition information” option and it reported: 09B1-97A5. As far as I understand it should be C12A7328-F81F-11D2-BA4B-00A0C93EC93B.

I also checked my running operative system disk (Ubuntu 14) and found that Gparted reports EB78-9AD2 for my actual boot partition UUID. What exactly is gparted reporting as UUID on my EFI system partition and why it doesn’t match with the expected C12A7328-F81F-11D2-BA4B-00A0C93EC93B ID?

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answered 1 Year ago aclavadoug · Accepted Answer

You're confusing filesystem UUIDs with partition GUIDs. The former are stored within the filesystems and can be used in Linux's /etc/fstab file or by the mount command via the UUID= parameter. (Despite the "UUID" name, they aren't always true UUIDs. FAT doesn't use UUIDs, for instance, so for FAT, the serial number is used instead of a UUID.) These UUIDs should be unique for any given filesystem, although cloned filesystems might have duplicated UUIDs.

Partition GUIDs, by contrast, are available only on GPT disks. There are actually two GUIDs associated with a partition:

A type code GUID, which is what the C12A7328-F81F-11D2-BA4B-00A0C93EC93B figure is. That particular GUID identifies an EFI System Partition (ESP). This is equivalent to the one-byte partition type codes of an MBR disk.

A partition's unique GUID, which, like a filesystem UUID, should be unique to any particular partition. The EFI uses this GUID internally, and some versions of Linux utilities enable you to use it much like a filesystem UUID, but using the PARTUUID= label rather than UUID=.