De man fstab
:
Instead of giving the device explicitly, one may indicate the (ext2 or xfs) filesystem that is to be mounted by its UUID or volume label (cf. e2label(8) or xfs_admin(8)), writing LABEL= or UUID=, e.g., 'LABEL=Boot' or 'UUID=3e6be9de-8139-11d1-9106- a43f08d823a6'. This will make the system more robust: adding or removing a SCSI [or SATA] disk changes the disk device name but not the filesystem volume label.
Quanto ao motivo pelo qual o GRUB falha ao inicializar às vezes, duvido que a configuração do UUID altere qualquer coisa (como parece