Configuration Requirements for Cross-Cluster Replication

Failover and Replication in a Cluster 6-13

6.2.4.1.4 Failover When a server within a cluster fails, the local load balancer is

responsible for transferring the request to other servers within a cluster. When the entire cluster fails, the local load balancer returns HTTP requests back to the global load balancer. The global load balancer then redirects this request to the other local load balancer.

6.2.4.2 Configuration Requirements for Cross-Cluster Replication

The following procedures outline the basic steps required to configure cross-cluster replication.

1. Install WebLogic Server according to your network configuration and

requirements. This includes installing a WebLogic Server instance on every physical machine that hosts a WebLogic Server instance.

2. Install and configure the hardware load balancers. For more information on load

balancer requirements see Section 6.2.4.1, Network Requirements for Cross-cluster Replication. For more information on installing and configuring load balancers, see the documentation for your load balancer. Following are some general considerations when configuring hardware load balancers to support cross-cluster replications: ■ You must configure your load balancer to maintain session IDs. If the load balancers do not maintain session ID, subsequent requests will always be sent to a new server. For more information, see Section 6.2.3.1, Connection with Load Balancing Hardware. ■ You should ensure that the cluster failover timeout value is not set to high. This value should be around 3-5 seconds. Some hardware load balancers have default values that are much longer. ■ You must configure your load balancer to know which backup cluster to use when a primary cluster or server fails.

3. Create and configure your domains according to your cluster requirements.

In addition to creating and configuring your domains, you should also create and configure your clusters and Managed Servers. For information about creating and configuring domains, clusters, and Managed Servers, see the following topics: ■ Understanding Oracle WebLogic Server Domains in Understanding Domain Configuration for Oracle WebLogic Server ■ Select Optional Configuration in Creating Domains Using the Configuration Wizard Following are some considerations when configuring domains to support cross-cluster replication: ■ Each domain should be set up and configured identically. In addition to identical domain, cluster and server configuration, the number of servers clusters, etc. should be identical. ■ Application deployment should be identical in each domain. Note: Cross-cluster replication requires that each cluster be assigned to a different domain. 6-14 Using Clusters for Oracle WebLogic Server ■ When setting up your domains, you must enable trust between both domains. For more information on enabling trust between domains, see Enabling Trust Between WebLogic Server Domains in Securing Oracle WebLogic Server 4. If you are using cross-cluster replication in a WAN environment, you must create a data source that is used to maintain session state. For more information, see Section 6.2.4.6.3, Database Configuration for WAN Session State Replication. 5. After you have created and configured your domains, servers, and clusters you should verify the configuration elements specific to cross-cluster replication have been configured correctly. These parameters must be configured identically for both domains. Table 6–2 lists the subelements of the cluster element in config.xml that are used to configure cross-cluster replication:

6.2.4.3 Configuring Session State Replication Across Clusters