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Load balancing is an enterprise-level feature in which the application server automatically alternates requests among the server instances in a cluster. Clustering also enables application servers to route requests to a running server instance when the original server instance goes down.
Note: These instructions apply only when you are running ColdFusion MX in the multiserver configuration. If you are running JRun4, you can also create clusters in the JMC.
You can get load balancing and failover by deploying identical ColdFusion applications and configurations to multiple server instances and adding the instances to a cluster. Each instance must have the same applications deployed and the same resources configured (such as data sources, Verity collections, and mappings). The web server connector optimizes performance and stability by automatically balancing load and by switching requests to another server instance when a server instance stops running.
Note: Because clustering uses Jini Network Technology, you must be connected to a network for clustering to work.
For maximum failover protection, use multiple computers in a cluster. However, you must purchase a separate ColdFusion MX Enterprise Edition license for each computer.
Note: If you set up and test multiple server instances while running the 30-day Trial version, the cluster might not continue to function appropriately when the Trial version reverts to the Developer version after 30 days.
To implement session failover for the server instances in a cluster, you must enable session replication for each server instance. Session replication coordinates session information in real-time among the server instances in a cluster. Enabling session replication lets JRun automatically route a request to a running server if the current server is unavailable.
Note: When a cluster uses session replication, session data is copied to other servers in the cluster each time it is modified. This can degrade performance if you store a significant amount of information in session scope. If you plan to store a significant amount of information in session scope, consider storing this information in client variables saved in a database.
Note: A server can participate in only one cluster. When adding remote instances to a cluster, ensure that the instance is not already part of a cluster.
Note: To administer a cluster, at least one member server instance must be running.
The ColdFusion MX Administrator adds the cluster to the Configured Clusters area.
The Edit Cluster screen appears.
Note: When you enable sticky sessions, the connector does not always route requests strictly based on the cluster algorithm. For more information, see Administrator online Help.
Note: Session variables are the only memory variables that support session replication. In particular, ColdFusion components do not support session replication.
jrun.trusted.hosts
property.
Note: This step is required only for servers that are not on the same subnet; it is not necessary if all servers are on the same subnet.
-coldfusion
option (command-line). For more information, see Web server configuration.
deactivated
attribute is set to false
.
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