I can partially answer your question and I'll need to talk to some of my experts to get a more complete answer. I recently had a lab environment of VSAs that I was using to create video demos. One of the things I wanted to show was how easy it is to scale-up a cluster, swap in nodes, and do a cluster swap, and migrate volumes. However, in my demo, I didn't have a multi-site cluster. Here's the video that is brand new showing what I did. https://youtu.be/4cod6XP_eIY
What I don't know is how to do a cluster swap when you have a multi-site cluster. I'm going to guess the process is the exactly the same - you would first create your multi-site cluster from your new StoreVirtual 4530 nodes and then do the cluster swap. Here's a screen grab from the demo showing me swapping a two node cluster with two new nodes.
Image may be NSFW.
Clik here to view.
I'm pretty confident to say that in your case, once you have created your new multi-site cluster, when you go into CMC to do the Swap Cluster Storage System, you would see all your new nodes from both sites and you'd proceed with the swap as I show in the video. I'll confirm this with one of my StoreVirutal experts and if my assumption is wrong, I'll let you know.
Another option to migrate your data from your old environment to your new is to migrate the volumes. I also show this in the demo. I'm not sure which is the best approach - I'll ask my StoreVirtual experts what they think.
Let me know if you have more questions.
