Can you give us some idea how the migration is done?
Just to reiterate -- we need to migrate because our existing FOSS Zimbra 4.5 is running on Fedora 4 -- which is not supported by Network Edition.
We cannot upgrade the OS to RHEL because the server is live and has to be up all the time.
So we plan to get a new machine and install RHEL 5 on it and then install Zimbra 4.5 (or 5 if it is released) Network Edition on it, and then migrate mails/accounts/ data from the live FOSS Zimbra 4.5/Fedora 4 to the new machine. The new machine will be configured exactly like the live machine. And the migration should incur minimal downtime -- I know downtime is inevitable because FOSS does not have live backup.
Am I right to say to we will need to install a DNS server on the new machine that points the URL (same for both live and new machines) to the IP of the new machine instead of the live machine?
Is the migration instructions here:
Network Edition Moving from Open Source to Network Edition ZCS - Zimbra :: Wiki