We're getting ready to migrate from 7.2.1 NE to 8.0.4. I was thrilled to see that Zimbra is finally supporting CentOS with 8.0.4 so we're planning to migrate from RHEL to CentOS at the same time. The only question is what the best method is. We've looked at the wiki page for RHEL 5 to RHEL 6 upgrade options (Rhel5 to rhel6 upgrade options - Zimbra :: Wiki). From what support has told us, they won't support 7.2.1 on CentOS at any point in time so the modified rsync option is not really an option. According to support the only option going from RHEL 5 to CentOS 6 is the first option where you add a CentOS 6 server (running 8.x) as an LDAP slave to an existing installation and then use the zmmboxmove command to move mailboxes from one server to another.
As an aside we're a relatively small organization with 262 user mailboxes, 110GB of local storage, and 265GB of HSM storage.
I understand that this loses the single instance store and you need to run the zmdedupe tool to get things back in line. But I remember the Zimbra support engineer mentioning that there was a potential for blowing your installation out of the water when promoting / demoting LDAP servers if you didn't do it correctly.
Has anyone used this method to migrate from 7.x to 8.x? Did it work OK? Did you have any problems? What would your recommendations be?
THANKS in advance!