A high availability manager consumes valuable system resources, such as CPU cycles, heap memory, and sockets. These resources are consumed both by the high availability manager and by WebSphere Application Server components that use the services that the high availability manager provides. The amount of resources that both the high availability manager and these WebSphere Application Server components consume increases exponentially as the size of a core group increases. For large core groups, the amount of resources that the high availability manager consumes can become significant. If the services that the high availability manager provides are not used, then disabling the high availability manager frees these resources.
The capability to disable the high availability manager is most useful for large topologies where none of the high availability manager provided services are used. In certain topologies, only some of the processes use the services that the high availability manager provides. In these topologies, you can disable the high availability manager on a per-process basis, which optimizes the amount of resources that the high availability manager uses.
Do not disable the high availability manager on administrative processes, such as node agents and the deployment manager, unless the high availability manager is disabled on all application server processes in that core group.
Some of the services that the high availability manager provides are cluster based. Therefore, because cluster members must be homogeneous, if you disable the high availability manager on one member of a cluster, you must disable it on all of the other members of that cluster.
Memory-to-memory replication
Memory-to-memory replication is a cluster-based service that you configure or enable at the application server level. If memory-to-memory replication is enabled on any cluster member, then the high availability manager must be enabled on all of the members of that cluster. Memory-to-memory replication is automatically enabled if:
Singleton failover
Workload management routing
Workload management is used for routing EJB Internet Inter-ORB Protocol (IIOP) traffic. Workload management uses the high availability manager to make the routing information highly available. Although routing information among cluster members is normally a cluster-based service, it does not have to be cluster-based. Under normal circumstances, you must leave the high availability manager enabled on any application server that exports or uses IIOP routing information. When the high availability manager is responsible for routing information between cluster members routing tables are dynamically built and maintained.
On-demand configuration routing
The on-demand configuration is used for proxy server routing. The high availability manager must be enabled on all processes to which the proxy server is used to route work.
Best practices
Related concepts
Core groups
Core group scaling considerations
High availability manager
Related tasks
Disabling or enabling a high availability manager