Create a Basic Cluster

Purpose

This OBE tutorial is designed to get you started with new cluster of WebLogic Servers. After starting the servers, you use their logs as well as the administration console to confirm that each joined the cluster successfully. Additional OBE tutorials extends this cluster's capabilities to support load balancing and failover of JavaEE applications.

Time to Complete

Approximately 30 minutes

Topics

This OBE tutorial covers the following topics:

	Overview
	System Requirements
	Creating a Cluster of Existing Servers
	Starting the Clustered Servers
	Monitoring the Cluster
	Summary
	Related information

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Overview

A WebLogic Server cluster consists of multiple WebLogic Server instances, running simultaneously and working together to provide increased scalability and reliability. A domain includes one or more WebLogic Server instances, which can be clustered, nonclustered, or a combination of clustered and nonclustered instances. A domain can include multiple clusters.

A cluster appears to clients as one WebLogic Server instance. The server instances that constitute a cluster can run on one machine or on different machines. You can increase a cluster’s capacity by adding server instances to the cluster on an existing machine, or by adding machines to the cluster to host the incremental server instances.

All server instances in a cluster use multicast or unicast to broadcast regular server heartbeat messages to other members of the cluster. Each heartbeat message contains data that uniquely identifies the server that sends the message. Servers broadcast their heartbeat messages at regular intervals. In turn, each server in a cluster monitors the multicast or unicast address to ensure that all peer servers’ heartbeat messages are being sent.

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System Requirements

Make sure that your system environment meets the following requirements:

Software Requirements

Before starting this tutorial, first complete the following prerequisite tutorials:

Installing and Configuring Oracle WebLogic Server
Configuring Oracle WebLogic Server Managed Instances
Using the Administration Console

Minimum Hardware Requirements

Item	Specification
Processor Speed	1 GHz
Memory	2 GB
Free Hard Disk Space	1 GB

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Creating a Cluster of Existing Servers

Perform the following steps:

If any of your managed servers are running, shut them down. For example, using the administration console, select Environment > Servers from the Domain Structure panel. Then click the Control tab.

Select the check box for each managed server. Click the Shutdown button and select Force Shutdown Now.

Click Lock & Edit in the Change Center panel of the administration console. Select Environment > Clusters from the Domain Structure panel. Click the New button.

Enter the following:

Field	Value
Name	dizzyworldCluster
Messaging Mode	Multicast
Multicast Address	(use default)
Multicast Port	(use default)

Click the OK button.

Tip: For multicast communication to function properly, your machine's network interface must be active.

Select the new cluster. Click the Configuration > Servers tab.

Click the Add button.

Select one of your managed servers and click Finish.

Repeat the previous steps to add the remaining two managed servers to the cluster.

In the Change Center panel, click Activate Changes.

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Starting the Clustered Servers

Perform the following steps:

Start one of your managed servers. From a shell, change directories to <domain>\bin and use the startManagedServer script. For example:

>./startManagedWebLogic.sh dizzy1 localhost:7001

Supply your administrative credentials, if prompted.

Watch the server start up using the shell's standard output stream. At some point, you should see it begin listening for cluster communication and begin waiting to synchronize with other servers in the cluster. Because the other servers have not started, there is nothing for it to synchronize with yet:

Tip: If your managed server's Standard Out Severity Level is not set to Notice or lower, these log messages will not be shown in the shell. Alternatively, use the console to view the contents of the server's log file.

Repeat the previous steps to start the other two managed servers. Once again, use the shell's standard output stream or the server log to confirm that the servers joined the cluster successfully:

Tip: If your managed server's Standard Out Severity Level is not set to Info or lower, these log messages will not be shown in the shell. Alternatively, use the console to view the contents of the server's log file.

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Monitoring the Cluster

Perform the following steps:

Return to the administration console. Select Environment > Clusters from the Domain Structure panel. Then select your cluster.

Click the Monitoring tab.

The resulting table should indicate that all the three managed servers are currently participating in the cluster. Various communication statistics are also available.

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Summary

In this lesson, you learned how to:

	Define a new cluster by using the administration console
	Configure cluster communication parameters
	Use the server log to analyze a server's participation in a cluster
	Use the administration console to monitor a cluster

Related Information

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