A cluster partition allows you to define a subset of a cluster consisting of primary and backup servers. You can configure individual components, message queues, and topics to be serviced only by the servers in a specific partition. Each server can be assigned to multiple partitions.
A cluster can contain one or more partitions, and each partition identifies preferred servers and alternate servers. Cluster partitions provide an effective way to perform load balancing without sacrificing high availability. Client requests are handled by one or more of the preferred servers in a partition, unless there are none available, in which case, the alternate servers handle the requests.
You can implement “hot standby” by creating a cluster partition with two members, a preferred server and an alternate server.
To facilitate cluster synchronization, Sybase recommends that you do not assign a cluster’s primary server to a cluster partition.
In the Management Console, highlight the Cluster Partitions icon, right-click, and select Add.
Complete the wizard, and select Finish.
Add servers to the cluster partition.
Configuring a cluster partition
Expand the Cluster Partitions folder, and select the cluster partition to configure.
On the General tab, enter:
Load Balancing Monitor Select the load balancing monitor from the list. The configuration property name is loadBalancingMonitor.
Each cluster partition can use a different load-balancing monitor, however, it is best to choose a load-balancing monitor that matches the thread monitor being used by the servers across which the load is balanced. To determine which thread monitor is being used, check the web.threadMonitor, ejb.localThreadMonitor, and ejb.remoteThreadMonitor properties in the Ant configuration scripts for your deployed EJB and Web modules.
Resolve Cache Timeout The number of seconds for a server to wait before rereading the property files to detect cluster changes (new or deleted cluster members); the default is 60 seconds. The configuration property name is resolveCacheTimeout.
Preferred Servers Select the preferred servers for this partition. Choose Select, then pick the servers individually. To add all the servers, select All; to add none of the servers, select None. The configuration property name is preferredServers, which defines the preferred servers in a comma-separated list.
Alternate Servers Select the alternate servers for this partition. If the preferred servers are unavailable, the alternate servers handle the requests. To add all the servers, select All; to add none of the servers, select None. The configuration property name is alternateServers, which defines the alternate servers in a comma-separated list.
Assigning an EJB component to a cluster partition
using the Management Console
In the Management Console, expand the EJB Modules folder, and select the EJB to configure.
On the Advanced tab, enter the name of the cluster partition, then click Apply.
Select Synchronize to update the value of the cluster partition in the Ant configuration file that defines the EJB.
Assigning a message queue or topic to a cluster
partition using the Management Console
In the Management Console, expand the Resources folder and either the JMS Message Queues or JMS Message Topics folder.
Select the message queue or topic to configure.
On the General tab, select the cluster partition from the list. Click Apply.
Assigning an EJB component to a cluster partition
by editing the Ant configuration file
In the Ant configuration file that defines the EJB component, enter the following property definition, where myPartition is the name of the cluster partition:
<clusterPartition partition_name = “myPartition”/>
