Clustering Overview

Individual WebApp Secure appliances have the ability to work together as one system in a cluster. Clustering allows traffic to be divided among multiple appliances, effectively reducing the per-system load. In a clustered network configuration, the master node holds the database that is populated by one or more traffic processors" In order to successfully utilize a WebApp Secure cluster, a load-balancer must properly segregate traffic to each of the defined traffic processing nodes. Each of these traffic nodes must maintain connectivity with the master in order to operate.

Note: Clustering should not be confused with High Availability. Clustering is used to increase throughput (by utilizing multiple processing nodes), and can reduce the chance that the whole system will fail. Clustering does not protect the master node from failure as in a High Availability setup; only HA configurations are set up to include failsafe procedures to designate a new master when the first one is unavailable.

In a traditional WebApp Secure deployment (one system), the appliance is responsible for holding its own database as well as processing the traffic. In a clustered deployment, you have the ability to segregate the database from those systems which will process incoming requests. During cluster configuration, you will have the ability to designate a node type for each system. At a minimum, the cluster must have a way to process traffic and a way to store the relevant information.

• Master: A master node is similar to a single-system deployment in that it holds the database, and also processes incoming traffic. This satisfies both requirements for a cluster (database and traffic processor) It is possible to set up a cluster with only one master node (no additional processing nodes). Additional traffic processing nodes can be added at a later point in time if desired.
• Dedicated Master: A dedicated master node holds the database similar to a master node, but it does not have the ability to process traffic. Using a dedicated master in a clustered configuration requires the addition of at least one traffic node.
• Traffic Processor: A traffic node is only responsible for processing incoming requests. It does not contain a database, so a master or a dedicated master node must accompany a traffic node. The number of traffic nodes you can add to a cluster is dependent on (1.) the hardware specifications of the master, (2.) the amount of incoming traffic on protected web application, and (3.) the number of additional traffic nodes in the cluster. For optimal stability, be sure to monitor the cluster's performance as you add each traffic node.