Just wondering if this is correct.

Have 2 zimbra servers..

Kick off the upgrade on main server stopping zimbra on the second one
run the database integrity check
let zimbra update version and start zimbra services on main server

run the upgrade mysql tables script on main server ( can the second server be running again now)

Do a full backup

Install the patch for 7.2.0 ( stop the second server)

kick off upgrade on second zimbra server leaving the main one running during the upgrade

Is that full backup necessary before installing the patch, just trying to estimate how long the system will be out of action.