I had to do a lot of work on our SAN/ESX server setup last night. And among it, something broke. As it is I was able to add the LUNs back to one ESX 4.1 host, and get all production servers up. However, the other 2 nodes can SEE the iSCSI targets and connect to them. They see the LUNs perfectly. However, they do not see the VMFS partition. So I am unable to add them to the other 2 nodes. The option to use the existing signature or re-signature them is greyed out. The only option that I have available is format. These same Luns are working perfectly on another node with identical hardware and an identical fresh install of ESX 4.1. WTF!? Why can't the other nodes use them?