How to migrate a two node ISE installation to a six node ISE installation

Question

How do we migrate from a two node ISE installation where the primary ISE has IP address A and the
secondary has IP address B to a six node ISE distributed installation with one primary admin ISE,
one secondary admin ISE, one primary monitoring ISE, one secondary monitoring ISE and
one PSN ISE with IP address A and finaly one PSN ISE with IP address B?
It is a production environment so we want to do the transition with minimal service impact.

Answer 1

I would assume your current setup is
Node 1 - Primary Admin, Secondary Monitor, PSN
Node 2 - Secondary Admin, Primary Monitor, PSN
Here is a high-level overview of what I think should be done. Keep in mind that it is only my opinion and ultimately I would recommend working with TAC to validate the process to ensure there is minimal impact.
TAKE A BACKUP of Configuration and Operational data.
Install the additional 4 nodes.
Register one as the secondary monitor.  This should remove the secondary monitoring role from the other node.
Register another node as the primary monitor. This should remove the primary monitoring role from the other node.
Register the last two nodes as administration nodes in the same process, doing the secondary admin node first, then finally the primary admin node.  This should leave the remaining PSN personas installed as the only persona on the original admin nodes.