Upgrading a single Zeus Server into a server farm

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Before you begin
The migration from a single machine to multiple machines is simple. However, it is always wise to make a backup of your current Zeus setup in case you make a mistake in the upgrade process. To do this, follow these steps:

1. Make a safe copy of the $ZEUSHOME/webadmin/conf/ directory from the Adminserver machine. This directory contains all the configuration information for all the websites you have set up.

2. Rename the old directory tree (mv $ZEUSHOME $ZEUSHOME.old)

The installation
Install the new Zeus Server and follow the installation instructions, until 'Stage 4: Adding websites' section. At this point, copy your preserved $ZEUSHOME/webadmin/conf/ directory onto the new Adminserver in the same location.

By default, the single Zeus Web Server install creates a 'backend' web server referred to as 'localhost'. The web server is also configured to only accept configuration requests from the local machine, and not from other machines on the network.

If the webserver is to be part of a cluster of machines, controlled by a load balancer, then this must be changed. Firstly, stop the webserver (by running $ZEUSHOME/stop-zeus), then edit the webserver configuration file $ZEUSHOME/web/global.cfg. There will be a line in the file reading:

controlallow localhost

Edit this line so that it reads:

controlallow all

This will then allow the machine to be controlled remotely. If desired, you can edit this line to restrict access to specific machines instead of allowing universal access.

Renaming the backend webserver
Restart the webserver (run $ZEUSHOME/start-zeus), then go to the 'cluster' page from the Admin Server. You will see a single machine 'localhost'. Click on the 'Configuration' link. This page allows you to specify which machines are in your cluster of webservers. Only one machine will appear there at the moment - this is your original Zeus Web Server. By default, it has the name 'localhost'. This must be changed for the machine to become part of a cluster. To do this, click the 'delete' button next to the machine. Then, add in the machine again, this time using the true hostname.

Starting up your website again
Reloadthe webserver status page (the traffic light page). This will now show all your old websites, in the non-running state.

To start the websites, just click on the traffic light to toggle it from red (non-running) to green (running). If you have lots of virtualservers, they can all be started by using the 'webctl' program available on the Adminserver machine.

Example usage:

$ZEUSHOME/webadmin/bin/webctl --action=start --allvs

This will start all virtual-servers on all machines in the cluster.