Use this task to configure a data replication domain to transfer data, objects, or events for session manager, dynamic cache, or stateful session beans. Data replication domains use the data replication service (DRS), which is an internal WebSphere Application Server component that performs replication services, including replicating data, objects, and events among application servers. If you configured a data replication domain with a previous version of WebSphere Application Server, you might be using a multi-broker replication domain. Any replication domains that you create with the current version of WebSphere Application Server are data replication domains. Migrate any multi-broker replication domains to data replication domains. To learn the differences between the two types of replication domains, see Comparison of multi-broker versus data replication domains and Migrating servers from multi-broker replication domains to data replication domains.
If you select the Configure HTTP memory-to-memory replication option when you create a cluster, the replication domain is automatically created for you.
To create a replication domain manually without creating a new cluster, click Environment > Replication domains > New in the administrative console.
On this page you can specify the properties for the replication domain, including timeout, encryption, and number of replicas. See Data replication domain settings for more information about the properties that you can configure for your replication domain.
To create a replication domain when you create a cluster, click Servers > Clusters > New in the administrative console. Then click Configure HTTP memory-to-memory replication. The replication domain that is created has the same name as the cluster and has the default settings for a replication domain. The default settings for a replication domain are to create a single replica of each piece of data and to have encryption disabled. To modify the replication domain properties, click Environment > Replication domains > replication_domain_name in the administrative console. See Creating clusters for more information about creating a cluster.
For more information about the replication domain settings that you can configure in the administrative console, see Data replication domain settings
The replication service uses threads obtained from the Default thread pool for various tasks, including processing messages. Other application server components also use this thread pool. Therefore, during application server startup the default maximum thread pool size of 20 might not be sufficient to allow the replication service to obtain enough threads from the pool to process all of the incoming replication messages. The number of incoming messages is influenced by the number of application servers in the domain and the number of replication domain consumers on each application server. The number of messages to be processed increases as the number of application servers in the domain increases and/or the number of replication consumers increases.
Persistent data not being replicated to the application servers during server startup might be an indication that you need to increase the setting for the maximum thread pool size. In larger configurations, doubling the maximum size of the Default thread pool to 40 is usually sufficient. However, if the number of application servers in a replication domain is greater ten and the number of replication domain consumers in each application server is greater than two, it might have to set the maximum thread pool size to a value greater than 40. See Thread pool settings for a description of how to change the maximum thread pool size setting.