Recently I ran into an issue creating some new storage clusters on two different vCenter servers. I had a problem where I was selecting the host cluster to create a storage cluster within, but the next button was greyed out.
I went through my own troubleshooting steps. 1. Did there have to be more than one datastore in order to create a cluster? No, because you can create a cluster with even local storage (on the same host) with one disk. 2. Are both the datastores the same? Yes, both on fiber (you cannot create a cluster with mixed datastore types (NFS / VMFS). 3. Are datastores stored between different sites? – No, both are in the same datacenter. 4. Do I have any replicated datastores? – No, not for this cluster. 5. Are all the hosts in the cluster esxi 5? Yes, all hosts are supported.
I also started to wonder… Do they need to be unformatted in order to do the initial setup for a storage cluster? No. Do they need to be at a certain VMFS level to join the cluster? Yes, Version 5.x or above. Are the datastores currently part of any other storage cluster? No.
After beating my head against it for a while it turns out you have to select the top level datacenter and then unselect all of the unwanted clusters to join the storage group. I had this happen on two different vCenters with build 455964. I then went to another environment with the same build and did not have this issue.
For more info on the general practice of creating a datastore cluster, visit myvirtualcloud.net.