Description of the illustration ha_n_plus_one.gif

This figure represents N+1 High Availability Model supported by Messaging Server. The figure includes three Active nodes: Host-A, Host-B, Host-C, and a single Backup node which is a standby for all the three Active nodes. The figure also includes three shared disk arrays, each of them storing the Message partitions and MTA queues of the respective active node which is controlling it. The backup node is capable of concurrently running Messaging Server from the three nodes. Upon failover of one or more active nodes, the backup node picks the failing node's responsibilities.