Hello, we are about to upgrade to the latest version of Zimbra supported by the x86 platform. We intend to upgrade to x86_64 at a future date. We have 1 ldap, 13 MX (receiving), 3 MTA (sending), 3 proxy, and 2 mailbox servers. Previously the upgrade process takes longer than is generally acceptable (10 hours) and extends in to business hours. We are expecting this update to take even longer.

We were hoping to break the upgrade in to stages and opened a ticket with Zimbra. They said it was possible and linked us to a wiki article that had specific versions of Zimbra all of which were older than the version we're currently at. I suspect this method works as long as the ldap schema doesn't change. I suspect that it does.

I would greatly appreciate any input as to whether the Zimbra team's suggestion of upgrading the ldap and then the MX servers in the first maintenance window and the rest as soon as possible is sensible and/or if anyone has any recommendations on how to break up the upgrade in a sensible way. We are trying to avoid an email outage to our customers during business hours.

I would also appreciate if anyone who has done this upgrade (6.0.10 to 7.2) could chime in with any caveats, pitfalls, or concerns that aren't listed in the documentation and/or maybe a few success stories would be great ^_^. Thank you!