Comparison of multi-broker versus data replication domains
Data replication domains replace multi-broker domains for data replication between application servers in a cluster.
Any replication domains that are created with a previous version of WAS might be multi-broker domains. Migrate any multi-broker domains to the new data replication domains. Although one can configure existing multi-broker domains with the current version of WebSphere Application Server, after you upgrade your deployment manager, one can create only data replication domains in the administrative console.
Multi-broker and data replication domains both perform the same function, which is to replicate data across the consumers in a replication domain. Configure all the instances of replication that need to communicate in the same replication domain. You can also configure the session manager with both types of replication domains to use topologies such as peer-to-peer and client/server to isolate the function of creating and storing replicas on separate application servers. You can control the redundancy of replication for each type of replication domain. With a data replication domain, one can specify a specific number of replicas.
If you used multi-broker domains with earlier releases of WebSphere Application Server, use the following comparison chart to learn the differences between how V5.x and V6.0 application servers use the two types of replication domains:
V5.x application servers using replication domains V6.0 application servers using replication domains Replication domain types Uses only multi-broker replication domains for replication. Servers that are using the current version of WebSphere Application Server can be configured to use both multi-broker replication domains and data replication domains for replication. The two types of domains provide backward compatibility with multi-broker domains that were created with a V5.x server. You should migrate any multi-broker domains to data replication domains. Data transport method Uses multi-broker domain objects that contain configuration information for the internal Java Message Service (JMS) provider, which uses JMS brokers as replicators. Uses data replication domain objects that contain configuration information to configure the high availability framework on WebSphere Application Server. The transport is no longer based on the JMS API. Therefore, no replicators and no JMS brokers exist. You do not have to perform the complex task of configuring local, remote, and alternate replicators. The earlier version of WAS did not support data replication domains. The current version of WAS can be configured to perform replication using old multi-broker domains by ignoring any JMS-specific configuration and by using the other parameters to configure replication through the high availability framework. Replication domain configuration The earlier version of WAS encourages the sharing of replication domains between different consumers, such as session manager and dynamic cache. The current version of WAS encourages creating a separate replication domain for each consumer. For example, create one replication domain for session manager and another replication domain for dynamic cache. The only situation where you should configure one replication domain is when configuring session manager replication and stateful session bean failover. Using one replication domain in this case ensures that the backup state information of HTTP sessions and stateful session beans are on the same application servers. Partial partitioning One can configure partial partitioning. Partition the replication domain to filter the number of processes to send data. Partial partitioning is deprecated. When using data replication domains, one can specify a specific number of replicas for each entry. However, if you specify a number of replicas larger than the number of backup application servers that are running, the number of replicas is the number of application servers that are running. After the number of application servers increases above your configured number of replicas, the number of replicas that are created is equal to the number that you specified. Domain sharing Multiple data replication service (DRS) instances share multi-broker domains. A limitation exists on the number of multi-broker domains that you can create because every multi-broker domain contains at least one replicator. A maximum of one replicator can be on each application server. All DRS instances in a replication domain use the same mode. Each replication domain must contain either client only and server only instances, or client and server instances only. For example, if one instance is configured to client and server, all other instances must be client and server. If one instance in a replication domain is configured to be a client only, one can add client only and server only instances, but not a client and server instance.
To migrate multi-broker domains to data replication domains, see Migrating V6.0 servers from multi-broker replication domains to data replication domains.
Replicating data across application servers in a cluster
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IBM is a trademark of the IBM Corporation in the United States, other countries, or both.