Universal Messaging 10.5 | Administration Guide | Setting up Active/Passive Clustering with Shared Storage | About Active/Passive Clustering | Failover Mechanism in an Active/Passive Cluster
 
Failover Mechanism in an Active/Passive Cluster
Universal Messaging runs as a service in a cluster. Within an active/passive cluster, there only be a single instance of Universal Messaging server running at any given time. The other Universal Messaging servers are inactive.
In a clustered environment, when a client makes a request to a server, the server handles the request much the same as in an unclustered environment, except that the server writes the client information to a shared disk instead of a private data store.
The following diagram illustrates the flow of documents through a typical clustered environment.
Steps
Description
1
Universal Messaging clients use the virtual IP address of the cluster to connect to the active/passive Universal Messaging cluster.
2
Cluster control software forwards the client request to the active server in the cluster.
3
The active server reads data from or writes data to the shared storage.
4
Universal Messaging returns the results to the client application.
The following diagram illustrates the failover in a clustered environment. If a server fails, subsequent requests for the session are redirected to a spare server in the cluster that is currently active and running.
Steps
Description
1
Universal Messaging clients use the virtual IP address of the cluster to connect to the active/passive Universal Messaging cluster.
2
The active server experiences failure and shuts down.
3
The cluster software returns the error code to the client.
4
Cluster control software marks the spare server as active.
5
Cluster control software forwards the client request to the active server in the cluster.
6
The active server reads data from or writes data to the shared storage.
7
Universal Messaging returns the results to the client application.