How Clustering Works

Each appliance in a cluster is a completely independent system that processes messages and provides access to the End User Web Quarantine and the administrative user interface. When in a cluster, appliances continually communicate with each other. This is facilitated by one appliance that acts as a configuration manager, which coordinates the flow of configuration information between the appliances that are joined in the cluster.

With the exception of system-specific information (such as hostname and IP address), configuration changes made on one appliance are sent to the configuration manager, which in turn propagates the changes to the other appliances in the cluster.

If an appliance becomes unresponsive or unreachable after two minutes, the other appliances designate the unreachable system as down. Its status is displayed in red, and the System Status button will indicate that there is a problem.

If the appliance becomes reachable again, the other appliances in the cluster respond, usually within twenty seconds, and its status is again displayed in green.

Note
In certain situations, network issues can result in an appliance becoming isolated from the rest of a cluster. The isolated appliance will be unable to reach the rest of the cluster, and will report this. The rest of the appliances in the cluster will continue to communicate with each other, and will only report that the isolated appliance is down.

Searching in a Cluster

You can use any appliance in a cluster to perform a search. If you search the quarantine logs or mail queue, you see data merged from the logs of all of the appliances in the cluster.

Note
if an appliance is unavailable when a full search of the cluster is performed, the results returned will not be complete. This will be indicated with a warning.

To perform a search of the quarantine logs or mail queue:

1. Select the appropriate search parameters on the Search tab . You can also choose whether to search either the entire cluster, or just a specific appliance in the cluster.

2. Your search request will be processed by the appliance that is acting as the configuration manager . The configuration manager will collect and merge data from the other appliances in the cluster.

3. These results will be then displayed on the Search tab.

Once an appliance is a member of a cluster, additional functionality and configuration options become available. For an appliance that is a member of a cluster, there are a number of pages that may display additional information, or have options that require additional configuration. For more information, see "Configuring Clustering."