To add additional information to the answer provided by Albert.
You need to keep in mind that each CommCell can only have 1 active CommServer (CS) at the time. You need to decide whether you are protecting both DataCenters (DCs) within the same CommCell, or whether you are starting a new CommCell from scratch.
> If the same CommCell will protect both DCs. Only 1 active CS will be allowed, it will either be hosted in the old or new DCs, both DCs will need to have communications and you can host MediaAgents (MAs) i both sites, but commanded by the single CS.
Under this approach, if you want to move the CS from one DC to another, you will be looking at a CS Hardware Refresh - No additional license will be required since you are only moving your current CS to a different site
https://documentation.commvault.com/commvault/v11_sp16/article?p=4739.htm
> If different CommCells will protect each DC. You will have 2 CS, and each will need its own license with different CCID. There is no way of bypassing this. Once you are ready to decomm the Cell in your old DC, you will be potentially looking at a CommCell Migration to move the legacy clients into the new environment
https://documentation.commvault.com/commvault/v11_sp16/article?p=5078.htm
So it really depends on the approach you are taking. But the first one (Single CommCell with CS Hardware Refresh) will definitely be the most efficient one.
Regards,
Javier