If you want to install the CentraSite Application Server Tier and CentraSite Registry Repository on different machines, or in the same directory but at different times, you must install the Registry Repository first.

If you install the new CentraSite on the same machine as the old CentraSite, you will not be able to run both products at the same time, even if they use different ports, because of conflicts for IPC and shared memory resources.