I tested vSphere 6 quite intensively when it was in beta, but I didn’t ever upgrade my lab - basically because I need a stable environment to work on and I wasn’t sure that I could maintain that with the beta. Now 6 has been GA a while and I have a little bit of time, I have begun the lab upgrade process. You can see a bit more about my lab hardware over on my lab page.
PowerCLI Script to set RDM LUNs to Perennially Reserved – Fixes Slow Boot of ESXi 5.1 with MSCS RDMs
I’ve previously posted around this topic as part of another problem but having had to figure out the process again I think it’s worth re-posting a proper script for this. VMware KB 1016106 is snappily titled “ESXi/ESX hosts with visibility to RDM LUNs being used by MSCS nodes with RDMs may take a long time to boot or during LUN rescan” and describes the situation where booting ESXi (5.1 in my case) takes a huge amount of time to boot because it’s attempting to gain a SCSI reservation on an RDM disk used by MS Clustering Services.