Managing replication in your cluster
IBM® WebSphere® Application Server provides a replication service. This service transfers data, objects, or events among application servers. Data replication can be used to make data for session manager, dynamic cache, and stateful session beans available across many application servers in a cluster.
About this task
Note: By default, the cluster scripts enable dynamic caching for each cluster
member. The replication type is set to NOT SHARED.
- Dynamic caching
- Data replication service (DRS) is the internal WebSphere Application
Server component that
replicates data among application servers. There are several types
of data replication, and WebSphere Portal can use
data replication for dynamic caching and for memory-to-memory replication
of session data. Enabling data replication for dynamic caching in
a cluster environment is necessary to maintain data integrity between
multiple WebSphere Portal nodes
in the cluster. Replication also helps improve performance by generating
data once and then replicating it to other servers in the cluster.
- AIX® HP-UX Linux Solaris Windows: Dynamic cache service settingsDB2 for z/OS tip: If you use the IBM DB2 Universal Database™ for z/OS® JDBC type 2 driver, you must set the JDBC driver custom property fullyMaterializeLobData to false. See Data sources for information.
- IBM i: Dynamic cache service settingsDB2 for z/OS tip: If you use the IBM DB2 Universal Database for z/OS JDBC type 2 driver, you must set the JDBC driver custom property fullyMaterializeLobData to false. See Data sources for information.
- AIX® HP-UX Linux Solaris Windows: Dynamic cache service settings
- Distributed sessions
- WebSphere Portal can
use the WebSphere Application
Server capabilities
to support HTTP session failover, which enables one node in a cluster
to access information from the existing HTTP session in a failure
in the cluster node originally handling that session. This capability
is referred to as distributed sessions. WebSphere Application
Server provides two techniques
that can be used for distributed sessions, either of which can be
used in a WebSphere Portal cluster. Distributed
session support is not enabled by default, so you must determine whether
to provide this capability in your cluster. And, if so, which of the
two techniques you use: memory-to-memory session replication and database
session persistence.Warning: The memory-to-memory session application can lead to low memory conditions if failures cause replication to fail. This condition can occur because the local and backup sessions are stored in the JVM memory. Therefore, failures with replicating the session data can prevent freeing the memory that is allocated for the backup session.
- AIX
HP-UX
Linux
Solaris
Windows:
- For general information, read Session management support.
- For memory-to-memory information, read Memory-to-memory replication.
- For database session information, read Configuring for database session persistence.
- IBM i:
- For general information, read Session management support.
- For memory-to-memory information, read Memory-to-memory replication.
- For database session information, read Configuring for database session persistence.
- AIX
HP-UX
Linux
Solaris
Windows:
Parent topic: Managing your cluster