Basically we all know, during to the SE licensing limitation, it offers including only one* array per site, in the project i was working, we had to involve a new array (Unity 500), and for that we were obligated to upgrade from SE to EX license. Preparing the system, to convert from SE to EX, is done with DM(Deployment Manager), where you chose to convert the system. The conversion is done two sites (or more) during the same time.. (I was told by some dellEMC engineers that the conversion is done site by site, but in the version i was running (5.x) it started converting both sites at the same time. Once the system has been converted (which is uninterrupted conversion), you can change the license via gui and cli (the gui is what i prefer), the licenses can be found under Administration > Manage my Licenses. Delete the SE licenses (if you are going back to the SE after EX, you can get them by EMC Licensing team under your sales order number), and browse to navigate to the EX licenses, after you have licensed the Arrays with EX license, you will be able to make any changes. * When you delete the licenses it doesn’t mean the replication stops, you just can’t make any changes during the time you are without license.
When going back to SE, there is no available option to convert again to SE, but you just delete the EX licenses and apply the SE licenses.
In (5.x) to see the LUNs you have to represent in your storage to the host (RPA), in (3.x) there was no need to push the LUN to RPA to see it, it fetched it automatically, but in newer version you have to represent it to the RP so the system could see it.