Recently, i setup a zimbra OSE for my own e-mail hosting. In a Xen vm. It wasnt working well, so i decided to move it to metal.
The problem was the lack of backup ability in OSE. It took me some time, but I've figured out a relatively clean way to migrate from one zimbra install to another. It involves using your standard tools to backup ldap, mysql, and the message store, and then moving it over to the target server, cleaning it up, and importing it.
Ive seen a number of threads on these forums regarding this topic. I'd tried a number of the procedures mentioned, none of which worked out for me. I think it was because of how dis-similar the two servers were. Hostname, address, physical location, vm vs. metal.
I've written-up the whole procedure on my blog. Have a look, suggest any tweaks that make sense.
I hope this helps out another admin looking to do a similar move. For that matter, anyone attempting to backup Zimbra OSE.