Upgrade from ns6 to ns7 via rsync: in doubt

I am doing some tests to upgrade our ns6 server to ns7 via rsync to a new hardware (maybe I will then bring it back to original server with new disks, but this is not the point). I am following the documentation, but this sentence made me panic a bit: “* close access to every network service on the source machine (except for SSH and httpd-admin)”!?
Is this temporary or also blocks restart of those services??
If something goes wrong, can I simply power off the new server and turno on the old one again or not??


It’s temporarily: for example you will not receive emails on old server to not create a difference between old and new server.

Yes, you can power off the new server and power one the old one and all will be as before.
You will not have any difference because services are stopped during the upgrade.