TecMint published a tutorial about upgrading from Red Hat Enterprise Linux 6 to 8.
How to Upgrade from RHEL 6 to RHEL 8
Red Hat Enterprise Linux 7 (RHEL 7) is the first major release that offers in-place upgrades from the earlier RHEL major release (RHEL 6) to a new major release of RHEL 7 operating system.
How to Upgrade from RHEL 6 to RHEL 8
