When installing Red Hat Enterprise Linux on a system with UEFI system and using a disk with an existing partitioning layout as the boot drive (the drive where the boot loader is installed), you may encounter the following error message during custom partitioning:
sda must have a GPT disk label
This happens because the boot drive (in this case,
sda) has a Master Boot Record (MBR) label, but UEFI systems require a GUID Partition Table (GPT) label. Therefore you can not reuse an existing partitioning layout on a MBR-labeled drive; the disk must be relabeled, which means you will have to create a new partition layout and lose all existing data.
To work around this problem, go back to the screen where you select your partitioning strategy. Select an option other than custom partitioning (for example Use All Space). Make sure to check the Review and modify partitioning layout check box, and click Next.
On the following screen, modify the automatically created layout so it suits your needs. After you finish and click Next, Anaconda will use your layout and relabel the drive automatically.