The nice thing about zimbra installations is that it's quite self contained. Generally, you can just take a copy of /opt/zimbra and put it somewhere safe and then if the upgrade goes badly, move the backup back in place and you can start the services quite easily.
That's not to say it's foolproof, problems do happen. The safest way if you are concerned would be to build a copy server, and copy the /opt/zimbra to it and perform the upgrade on the copy, so you can do it without touching the real server at all. Then upgrade the real server when you are happy with the process. |