Setting up High Availability
This section provides the steps for creating a highly available cluster, and testing HTTP session persistence.
This section discusses the following topics:
To Prepare the System for High Availability
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Install Application Server instances and the Load Balancer Plug-in.
For more information, see the Java Enterprise System Installation Guide (if you are using Java ES) or Sun GlassFish Enterprise Server v2.1.1 Installation Guide (if you are using the standalone Enterprise Server installer).
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Create Enterprise Server domains and clusters.
For information on how to create a domain , see Creating a Domain in Sun GlassFish Enterprise Server v2.1.1 Administration Guide. For information on how to create a cluster, see To Create a Cluster.
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Install and configure your web server software.
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Setup and configure load balancing.
For more information, see Setting Up HTTP Load Balancing.
Starting the HADB Management Agent
The management agent, ma, executes management commands on HADB hosts and ensures availability of the HADB node supervisor processes by restarting them if they fail.
You can start the management agent two ways:
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As a service, for production use. See Starting the Management Agent as a Service. To ensure availability of the management agent, make sure it is restarted automatically when the system reboots. See Ensuring Automatic Restart of the Management Agent.
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As a regular process (in console mode), for evaluation, testing, or development. See Starting the Management Agent in Console Mode.
In each case, the procedures are different depending on whether you are using Java Enterprise System or the standalone Application Server.
Configuring a Cluster for High Availability
Before starting this section, you must have created one or more Enterprise Server clusters. For information on how to create a cluster, see To Create a Cluster.
From the machine on which the Domain Administration Server is running, configure the cluster to use HADB using this command:
asadmin configure-ha-cluster --user admin --hosts hadb_hostname1,hadb_hostname2 [,...] --devicesize 256 clusterName
Replace hadb_hostname1, hadb_hostname2, and so forth, with the host name of each machine where HADB is running, and clusterName with the name of the cluster. For example:
asadmin configure-ha-cluster --user admin --hosts host1,host2,host1,host2 --devicesize 256 cluster1
This example creates two nodes on each machine, which are highly available even in case of HADB failover. Note that the order of the host names following the –hosts option is significant, so the previous example would be different than --hosts host1,host1,host2,host2.
If you are using just one machine, you must provide the host name twice. In production settings, using more than one machine is recommended.
Configuring an Application for High Availability
In Admin Console, select the application under Applications > Enterprise Applications. Set Availability Enabled and then click Save.
Restarting a Cluster
To restart a cluster in Admin Console, choose Clusters > cluster-name. Click Stop Instances. Once the instances have stopped, click “Start Instances.”
Alternatively, use these asadmin commands:
asadmin stop-cluster --user admin cluster-name asadmin start-cluster --user admin cluster-name
For more information on these commands, see stop-cluster(1) and start-cluster(1).
Restarting the Web Server
To restart the Web Server, type this Web Server command:
web_server_root/https-hostname/reconfig
Replace web_server_root with your Web Server root directory and hostname with the name of your host machine.
To Clean Up the Web Server Instance Acting as Load
Balancer
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