Your Boot Partition is on a Disk Using GTP

1. At the partitioning screen, press Ctrl + Alt + F2 to get to a shell prompt.

2. Overwrite the GPT partition label with an MSDOS label.

[root@host ~]# parted /dev/sda -s mklabel msdos

3. Press Ctrl + Alt + F6 to return to the partitioning screen, and continue installation, it may be needed to back one step up in order for the installer to see the new changes.

Root Cause

• The GRand Unifed Bootloader (GRUB) is not compiled with the ability to utilize GPT partitions in RHEL5.
• The MSDOS partition label will allow GRUB to boot correctly, but has a physical limitation of 2 TB.
• This above error was a check added in RHEL 5.2.
• In 5.0 and 5.1, the installation would continue but the ending install will not boot.

#Source- RHEL