These instructions describe how to upgrade the Zeus Traffic Manager or Zeus Load Balancer software images on Amazon EC2. For instructions on upgrading Zeus Traffic Manager software, please see here, and for virtual appliances or hardware appliances, please see here.
Upgrade strategy
Unlike physical machines or regular virtual appliances, which tend to be very long-lived, EC2 instances are intended to be transient. If an EC2 instance develops a fault, it is easier to terminate it and replace it with a new one than to try to repair it.
Upgrades can be handled in a similar way: instead of upgrading a running instance when a new version of the software is released, it is easier to start an instance of the newer software, migrate the configuration over from the old one, and then terminate the old instance. Using clustering and fault tolerant Traffic IP addresses it is possible to upgrade a cluster in place, replacing each traffic manager with one running a newer version of the software, while continuing to serve application traffic.
To upgrade using this method, your cluster must be at least one traffic manager instance smaller than the maximum size that your license key permits. This is because you will need to add a new traffic manager running the updated version of the software to your cluster before removing one of the older instances.
Upgrade howto
For each traffic manager in your cluster, perform the following steps:
- Start an instance of the new AMI.
- Using the Admin Server, or the user-data pre-configuration parameters, join the new instance to your cluster. Ensure that you set the new instance to join Traffic IP groups (join_tips=y, if using user-data pre-configuration). Note that per-node hostname mappings (configured the in System > Networking page) will not be migrated automatically - you must set these manually on each new instance.
- Terminate one of the old instances in your cluster.
Repeat these steps until all the traffic managers in your cluster have been replaced. Replace instances one by one - do not terminate an old instance until its replacement has successfully joined the cluster.
Upgrading to new product functionality
The instructions described in the previous section can also be used to change the product version you are running. For example, you can use this method to upgrade from the Zeus Load Balancer product to the Zeus Traffic Manager product, or to the same product but with a higher bandwidth limit.
Note that you cannot use this method to downgrade the product you are currently running to one with fewer features. If you want to change from the Zeus Load Balancer to the Zeus Simple Load Balancer for example, you must create a new cluster of Simple Load Balancer instances and migrate the relevant configuration from the old cluster manually.
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