A Netmail Store storage cluster routinely replicates content objects to other nodes in the same cluster in order to improve fault tolerance and performance. For disaster recovery and high availability, you can also replicate content objects to another remote cluster. A remote cluster can typically have the following properties:
- A different subnet than the local cluster.
- Connectivity to the local cluster using TCP/IP.
- One or more firewalls separating it from the cluster and external networks.
- Unpredictable network latency that might prevent communication for long periods of time.
The normal replication techniques used within a Netmail Store cluster are not appropriate for remote replication between clusters in different geographical locations. Therefore, a new mechanism is required. We call this Netmail Store Content Router. Content Router (CR) supplies a more appropriate mechanism for remote replication by providing disaster recovery, backup, and content distribution services between multiple Netmail Store clusters separated by wide area network links. It also allows you to enumerate Netmail Store content for other purposes, such as search indexing or virus scanning.