RHEL 6 source workload and ESX host (pre-4.0 U4)
When RHEL 6 workload is protected to ESX host (pre-4.0 U4), warning messsage appears indicating of unsupported confiugaration. VMware doesn't support RHEL 6 guest OS on ESX host (pre-4.0 U4). Here is the link to VMware support compatibility guide:
Choose a supported ESX host for RHEL 6 guest OS.