Just a few reminders out there for those looking to upgrade to ESXi 5.5U1 from anything that is not 5.5. Keep in mind with this version that VMware removed drivers for devices that are not on the HCL. This includes a few NICs like Realtek and Marvell and possibly a few SATA controllers. In order to prevent you from this disaster the best way to accomplish the upgrade is using the profile update esxcli command. Details to follow soon!