I have just successfully upgraded the ESX 4.1 into ESXi 5.1u1 using the .ISO image to perform Forced migration with the Preserve LUN option.
However,to my surprise, I couldn't find some of the presented LUNs that are supposed to be presented on this one particular host ?
Before it was upgraded everything is presented successfully to the ESX host, but now some of them are missing. During the host upgrade and also after the upgrade, the reboot is taking ages (more than 5 hours to successfully running due to the number of LUNs presented to each host is around 13-20 with some of them have been removed as well).
because of this issue, I'm not confident to perform the manual ESX to ESXi upgrade in my production environment with Vmware Update manager for all of my remaining ESX hosts to ESXi ( I got 47 remaining with).