Hi all,
I'm considering migrating zimbra from a virtual machine, name example: ACTIVE (CentOS 5.6 x86) to a new virtual machine (CentOS 6.2 x86_64) , name example: STANDBY.
I'd like some tips on how to do.
The two servers are configured with different IP and different names and on the same LAN, mails are sent/receive through a relay (MailScanner).
The name resolution is managed with internal DNS and the MX record points now to the ACTIVE server (for the clients point of view).
I run a first migration with ZeXtras and transaction was OK. I' ve all mails, calendars, etc on the STANDBY server. 
Now the steps on final job:
- Mails stop on MailScanner (maybe with iptables, stopping MailScanner, etc ), don' t flow to ACTIVE server.
- Final Migrations with ZeXtras.
- Stop ACTIVE server
- Remove ACTIVE "A record" server from DNS.
- Add an ALIAS ACTIVE to point at STANDBY, reload BIND, wait Slaves Nameserver for updates their db.
Question: Clients with Zimbra Desktop must be stopped during migration?
- Change postfix Transport map on MailScanner, reload postfix/MailScanner.
- Enable mails from MailScanner to flow to new server.
Every answer is appreciated.
Thanks, Luciano