With a shared diskgroup, it is managed by cvm, and whenever it gets imported on one node, it will be automatically imported on the other node as well. So when exactly will the setting 'CVMActivation=ew' work with VCS? I tried setting that, but as soon as I tried to online the resource group on one node, the dg got imported on both node and it got the activation mode:
cluster-actv-modes: HostA=sw HostB=sw
And it would never succeed in setting the mode to 'ew' because it was 'conflicting' with 'sw' on the other node.
VxVM vxdg ERROR V-5-1-3424 Disk group test.gnr.0: activation failed: Node activation conflict
It is stated in the admin guide that when a diskgroup is activated in cluster as 'exclusivewrite', attempt to activate the diskgroup on another node as anything would fail EXCEPT 'sharedread'. So if I really want a 2-node cluster to work properly where the shared diskgroup would only be writable on one node and read-only on the other node, how exactly should the VCS config look like?
In theory, as you stated, if one node is set to ew then rest all node should be sr. Therefore in your case ideally it should look like below.
cluster-actv-modes: HostA=ew HostB=sr, if you want to give exclusivewrite permission to HostA.
Try to perform a test if possible, create a new shared dg and make it a part of cluster set the CVMActivation as mentioned above. Start the cluster on the node that has ew set and then start the other node once first node is up and running. Let us know how that goes.