Thanks Prachand,
To eliminate risk as much as possible, I would like to have a secondary incase the primary server upgrade fails, then I am stuffed.
One other question,
In each sav environement, each client will have a parent server. I would like the primary servers to manage all the clients and not the secondary as this server is already performing lots of otther functons. How do I best configure that if the primary servers fails at any time and the secondary is promoted to the primary that all the clients will move across to the new primary (ie the secondary that now is the primary)?