Replicating data across application servers in a cluster

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 component that performs replication services, including replicating data, objects, and events among application servers.

Before you begin

Determine if you are using a multi-broker replication domain. If you configured a data replication domain with a previous version of the product, you might be using a multi-broker replication domain. Any replication domains that you create with the current version of the product are data replication domains. You should migrate any multi-broker replication domains to data replication domains.

About this task

Use this task to configure replication, a service that transfers data, objects, or events among the application servers in a cluster. Use replication to prevent loss of session data with session manager, to further improve the performance of the dynamic cache service, and to provide failover in stateful session beans.
Avoid trouble: If you select the Configure HTTP memory-to-memory replication option when you create a cluster, the replication domain is automatically created for you.gotcha

Similarly if, instead of WAS01Network , the cell name is simply WAS1, you have to pad the high level qualifier with the first three characters of the string DRSSTREAM. The high level qualifier then becomes WAS1DRS.

Complete the following steps to enable data replication among the application servers in a cluster.

Procedure

  1. Create a replication domain. Use one of the following methods to create a replication domain:
    • Create a replication domain manually.

      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.

    • Create a replication domain when you create a cluster.

      To create a replication domain when you create a cluster, click Servers > Clusters > 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 > New replication_domain_name in the administrative console.

  2. Configure the consumers, or the components that use the replication domains. Dynamic cache, session manager, and stateful session beans are the three types of replication domain consumers. Each type of consumer must be configured with a different replication domain. For example, session manager uses one replication domain and dynamic cache uses a different replication domain. However, use one replication domain if you are configuring HTTP session memory-to-memory replication and stateful session bean replication. 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.

Results

Data is replicating among the application servers in a configured replication domain.

What to do next

If you select DES or 3DES as the encryption type for a replication domain, an encryption key is used for the encryption of messages. At regular intervals, for example once a month, you should go to the Environment > Replication domains > New page in the administrative console, and click Regenerate encryption key to regenerate the key. After the key is regenerated, you must restart all of the application servers that are configured as part of the replication domain. Periodically regenerating the key improves data security.



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Last updated: Oct 22, 2010 12:21:29 AM CDT
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