Yes, you can add the host to one of the existing storage groups that have the same LUNs that you want present to this new host (it sounds as if your storage groups have exactly the same LUNs anyways) and then just need to rescan the ESX storage adapters.   Just to mention it, even if you tried you wouldn't be able to change the Host ID to LUNs that already exist in the storage group.  As mentioned above, if you needed to (which you don't), you have to take the LUN out of the storage group and add it back with the appropriate value.
Hi all,  At the moment I am running a pair of Dell R900s through a pair of Brocade 200e switches to a CX3-10 SAN. I need to add an extra host, which has two HBAs, one connected to each of the 200e switches. When the Dell guy set this up initially he created two storage groups, one for each ESX host which I have been told is a rather strange way to do it. Originally I was going to create a third storage group to put my new server in, and then add the LUNs in the other two groups to this new third one as well, however would it not be easier to simply add the new host to one of the existing storage groups?  Any problems with doing this? I assume that by doing this, all of the LUN IDs etc would be the same?  Cheers  JD
Storage groups and expanding ESX cluster