Hi all !

Our Zimbra installation is getting quite old, it is time for us to upgrade.
Here is the situation :
  • OS is Fedora Core 4
  • Zimbra is OSE 4.5.11
  • the server's address is mail.domain.be, and we have an alias and a
    "catch-all forwarding" from domain.eu to domain.be

We need to upgrade to Zimbra 5.x, and that means upgrading the OS since FC4 is not supported anymore.
We also need to slightly upgrade the hardware because we are getting low on free disk space.
We would like to fully rename our domain from domain.be to domain.eu (we never use the .be extension, and it is very confusing for the users and the administrators to maintain everything on the .be domain).

Of course, we would like to do this migration with no downtime and no service disruption ! (no, just joking, but minimal downtime is best of course)

I checked the wiki (migrationfromeol and backup/restore), but still have a fex questions. Here they are :

  1. What would be the best choice for the new OS ?
    I was thinking about Ubuntu LTS, but 8.04 is not available for 4.5.11, so there would be an extra set from 6.04 LTS to 8.04 LTS.
    I was also thinking about Centos5 for no particular reason except that people say it is a good server OS.
    I have no personal preference and my Linux knowledge is pretty basic.
  2. Here is what I have in mind for the moment :
    1. install the new OS (say, Centos5) on a new temporary server with same FQDN but different IP address
    2. configure DNS so that secondary MX points to the new server (using an alias maybe)
    3. install Zimbra 4.5.11 on the new temporary server
    4. restore a fresh backup of zimbra on the new temporary server
    5. zmfixperm
    6. shutdown zimbra on the old server
    7. rsync /opt/zimbra from old server to new server
    8. start the new server
    9. and then same thing the other way : install new hardware/os on old server, switch back

    Now, since the temporary server's FQDN will not match it's IP address, the only solution would be to setup a split DNS on this server, right ?
    Is this the correct thing to do ?

    Is it enough to configure the MX (with lower priority) for my domain to point on the temporary server for it to pick up emails as soon as I shutdown the old server ?
  3. The "zmprov -l rd" command is not very documented. What does it really do ?
    I just have one domain on this server. Zimbra is configured with all addresses (ldap, etc...) pointing to zimbra.domain.be. Does renaming the domain from domain.be to domain.eu have any impact on this ?
    Since I already have an alias and a forward from domain.eu to domain.be, do I have to remove this alias before I rename the domain ?

Thanks a lot for helping me on this !