Chapter 7: Cluster Tuning
Chapter 3, “Component Tuning,” describes the component settings and implementation techniques that you can tune for single-server deployments. In a clustered deployment, these additional settings affect performance.
To allow load balancing when deployed in a cluster, your components must have the Automatic Failover option enabled on the Transactions tab in the EAServer Manager Component Properties dialog box. To configure this setting with jagtool or in the EJB deployment descriptor, set the property com.sybase.jaguar.component.auto.failover to true.
If your application uses stateful components such as EJB stateful session beans, you must configure a mechanism for EAServer to replicate state data between servers in the cluster. You can use a remote database server or in-memory replication. For more information, see Chapter 28, “Configuring Persistence for Stateful Session Components,” in the EAServer Programmer’s Guide.
If using in-memory replication, EAServer replicates state data between mirror pairs, that is, a pair of servers configured to share the same user session. In-memory replication can perform better than using a database, but requires more memory on each server. Configure the cache size and session timeout to control how much memory the cache uses. For instructions, see “Requirements for in-memory stateful failover” in Chapter 29, “Configuring Persistence Mechanisms,” in the EAServer Programmer’s Guide:
If using database replication, all servers in the cluster store session data in a remote database. This mechanism can perform slower than in-memory replication, but requires less memory. Also, EAServer can share a client’s session data on more than two servers. If using this technique:
Tune the connection cache settings as described in “Connection cache settings”.
Make sure the table used is indexed. For information on creating the database table, see “Table schema for binary storage” in Chapter 29, “Configuring Persistence Mechanisms,” in the EAServer Programmer’s Guide.
EJB CMP entity bean caching is described in “Entity instance and query caching”. When using this feature in a clustered deployment, you can configure the cache settings to determine whether cached data is synchronized between servers in the cluster. “Cache coherency and transaction consistency” discusses the pros and cons of cache synchronization. To configure this setting, follow the instructions in “Configuring object caching”.
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