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# 4 Administering GlassFish Server Clusters

A cluster is a collection of GlassFish Server instances that work together as one logical entity. A cluster provides a runtime environment for one or more Java Platform, Enterprise Edition (Java EE) applications. A cluster provides high availability through failure protection, scalability, and load balancing.

The Group Management Service (GMS) enables instances to participate in a cluster by detecting changes in cluster membership and notifying instances of the changes. To ensure that GMS can detect changes in cluster membership, a cluster's GMS settings must be configured correctly.

The following topics are addressed here:

- About GlassFish Server Clusters

- Group Management Service

- Creating, Listing, and Deleting Clusters

## About GlassFish Server Clusters

A cluster is a named collection of GlassFish Server instances that share the same applications, resources, and configuration information. For information about GlassFish Server instances, see Administering GlassFish Server Instances.

GlassFish Server enables you to administer all the instances in a cluster as a single unit from a single host, regardless of whether the instances reside on the same host or different hosts. You can perform the same operations on a cluster that you can perform on an unclustered instance, for example, deploying applications and creating resources.

A cluster provides high availability through failure protection, scalability, and load balancing.

- Failure protection. If an instance or a host in a cluster fails, GlassFish Server detects the failure and recovers the user session state. If a load balancer is configured for the cluster, the load balancer redirects requests from the failed instance to other instances in the cluster. Because the same applications and resources are on all instances in the cluster, an instance can fail over to any other instance in the cluster.

  To enable the user session state to be recovered, each instance in a cluster sends in-memory state data to another instance. As state data is updated in any instance, the data is replicated.

- Scalability. If increased capacity is required, you can add instances to a cluster with no disruption in service. When an instance is added or removed, the changes are handled automatically.

- Load balancing. If instances in a cluster are distributed among different hosts, the workload can be distributed among the hosts to increase overall system throughput.

## Group Management Service

The Group Management Service (GMS) is an infrastructure component that is enabled for the instances in a cluster. When GMS is enabled, if a clustered instance fails, the cluster and the Domain Administration Server (DAS) are aware of the failure and can take action when failure occurs. Many features of GlassFish Server depend upon GMS. For example, GMS is used by the in-memory session replication, transaction service, and timer service features.

GMS is a core service of the Shoal framework. For more information about Shoal, visit the Project Shoal home page.

The following topics are addressed here:

- Protocols and Transports for GMS

- GMS Configuration Settings

- Dotted Names for GMS Settings

- To Preconfigure Nondefault GMS Configuration Settings

- To Change GMS Settings After Cluster Creation

- To Check the Health of Instances in a Cluster

- To Validate That Multicast Transport Is Available for a Cluster

- Discovering a Cluster When Multicast Transport Is Unavailable

- Using the Multi-Homing Feature With GMS

### Protocols and Transports for GMS

You can specify that GMS should use one of the following combinations of protocol and transport for broadcasting messages:

- User Datagram Protocol (UDP) multicast

- Transmission Control Protocol (TCP) without multicast

Even if GMS should use UDP multicast for broadcasting messages, you must ensure that TCP is enabled. On Windows systems, enabling TCP involves enabling a protocol and port for security when a firewall is enabled.

If GMS should use UDP multicast for broadcasting messages and if GlassFish Server instances in a cluster are located on different hosts, the following conditions must be met:

- The DAS host and all hosts for the instances must be on the same subnet.

- UDP multicast must be enabled for the network. To test whether multicast is enabled, use the `validate-multicast`(1) subcommand.

If GMS should use TCP without multicast, you must configure GMS to locate the instances to use for discovering the cluster. For more information, see Discovering a Cluster When Multicast Transport Is Unavailable.

Note:

If you do not configure GMS to locate the instances to use for discovering a cluster, GMS uses UDP multicast by default.

### GMS Configuration Settings

GlassFish Server has the following types of GMS settings:

- GMS cluster settings — These are determined during cluster creation. For more information about these settings, see To Create a Cluster.

- GMS configuration settings — These are determined during configuration creation and are explained here.

The following GMS configuration settings are used in GMS for group discovery and failure detection:

`group-discovery-timeout-in-millis`

  Indicates the amount of time (in milliseconds) an instance's GMS module will wait during instance startup for discovering other members of the group.

  The `group-discovery-timeout-in-millis` timeout value should be set to the default or higher. The default is 5000.

`max-missed-heartbeats`

  Indicates the maximum number of missed heartbeats that the health monitor counts before the instance can be marked as a suspected failure. GMS also tries to make a peer-to-peer connection with the suspected member. If the maximum number of missed heartbeats is exceeded and peer-to-peer connection fails, the member is marked as a suspected failure. The default is 3.

`heartbeat-frequency-in-millis`

  Indicates the frequency (in milliseconds) at which a heartbeat is sent by each server instance to the cluster.

  The failure detection interval is the `max-missed-heartbeats` multiplied by the `heartbeat-frequency-in-millis`. Therefore, the combination of defaults, 3 multiplied by 2000 milliseconds, results in a failure detection interval of 6 seconds.

  Lowering the value of `heartbeat-frequency-in-millis` below the default would result in more frequent heartbeat messages being sent out from each member. This could potentially result in more heartbeat messages in the network than a system needs for triggering failure detection protocols. The effect of this varies depending on how quickly the deployment environment needs to have failure detection performed. That is, the (lower) number of retries with a lower heartbeat interval would make it quicker to detect failures.

  However, lowering this value could result in false positives because you could potentially detect a member as failed when, in fact, the member's heartbeat is reflecting the network load from other parts of the server. Conversely, a higher timeout interval results in fewer heartbeats in the system because the time interval between heartbeats is longer. As a result, failure detection would take a longer. In addition, a startup by a failed member during this time results in a new join notification but no failure notification, because failure detection and verification were not completed.

  The default is 2000.

`verify-failure-waittime-in-millis`

  Indicates the verify suspect protocol's timeout used by the health monitor. After a member is marked as suspect based on missed heartbeats and a failed peer-to-peer connection check, the verify suspect protocol is activated and waits for the specified timeout to check for any further health state messages received in that time, and to see if a peer-to-peer connection can be made with the suspect member. If not, then the member is marked as failed and a failure notification is sent. The default is 1500.

`verify-failure-connect-timeout-in-millis`

  Indicates the time it takes for the GMS to detect a hardware or network failure of a server instance. Be careful not to set this value too low. The smaller this timeout value is, the greater the chance of detecting false failures. That is, the instance has not failed but doesn't respond within the short window of time. The default is 10000.

The heartbeat frequency, maximum missed heartbeats, peer-to-peer connection-based failure detection, and the verify timeouts are all needed to ensure that failure detection is robust and reliable in GlassFish Server.

For the dotted names for each of these GMS configuration settings, see Dotted Names for GMS Settings. For the steps to specify these settings, see To Preconfigure Nondefault GMS Configuration Settings.

### Dotted Names for GMS Settings

Below are sample `get` subcommands to get all the GMS configuration settings (attributes associated with the referenced `mycfg` configuration) and GMS cluster settings (attributes and properties associated with a cluster named `mycluster`).

    asadmin> get "configs.config.mycfg.group-management-service.*"
    configs.config.mycfg.group-management-service.failure-detection.heartbeat-frequency-in-millis=2000
    configs.config.mycfg.group-management-service.failure-detection.max-missed-heartbeats=3
    configs.config.mycfg.group-management-service.failure-detection.verify-failure-connect-timeout-in-millis=10000
    configs.config.mycfg.group-management-service.failure-detection.verify-failure-waittime-in-millis=1500
    configs.config.mycfg.group-management-service.group-discovery-timeout-in-millis=5000

    asadmin> get clusters.cluster.mycluster
    clusters.cluster.mycluster.config-ref=mycfg
    clusters.cluster.mycluster.gms-bind-interface-address=${GMS-BIND-INTERFACE-ADDRESS-mycluster}
    clusters.cluster.mycluster.gms-enabled=true
    clusters.cluster.mycluster.gms-multicast-address=228.9.245.47
    clusters.cluster.mycluster.gms-multicast-port=9833
    clusters.cluster.mycluster.name=mycluster

    asadmin> get "clusters.cluster.mycluster.property.*"
    clusters.cluster.mycluster.property.GMS_LISTENER_PORT=${GMS_LISTENER_PORT-mycluster}
    clusters.cluster.mycluster.property.GMS_MULTICAST_TIME_TO_LIVE=4
    clusters.cluster.mycluster.property.GMS_LOOPBACK=false
    clusters.cluster.mycluster.property.GMS_TCPSTARTPORT=9090
    clusters.cluster.mycluster.property.GMS_TCPENDPORT=9200

The last `get` subcommand displays only the properties that have been explicitly set.

For the steps to specify these settings, see To Preconfigure Nondefault GMS Configuration Settings and To Change GMS Settings After Cluster Creation.

### To Preconfigure Nondefault GMS Configuration Settings

You can preconfigure GMS with values different than the defaults without requiring a restart of the DAS and the cluster.

1. Create a configuration using the `copy-config` subcommand.

   For example:

       asadmin> copy-config default-config mycfg

   For more information, see To Create a Named Configuration.

2. Set the values for the new configuration's GMS configuration settings.

   For example:

       asadmin> set configs.config.mycfg.group-management-service.group-discovery-timeout-in-millis=8000
       asadmin> set configs.config.mycfg.group-management-service.failure-detection.max-missed-heartbeats=5

   For a complete list of the dotted names for these settings, see Dotted Names for GMS Settings.

3. Create the cluster so it uses the previously created configuration.

   For example:

       asadmin> create-cluster --config mycfg mycluster

   You can also set GMS cluster settings during this step. For more information, see To Create a Cluster.

4. Create server instances for the cluster.

   For example:

       asadmin> create-instance --node localhost --cluster mycluster instance01

       asadmin> create-instance --node localhost --cluster mycluster instance02

5. Start the cluster.

   For example:

       asadmin> start-cluster mycluster

See Also

You can also view the full syntax and options of a subcommand by typing `asadmin help` subcommand at the command line.

### To Change GMS Settings After Cluster Creation

To avoid the need to restart the DAS and the cluster, configure GMS configuration settings before cluster creation as explained in To Preconfigure Nondefault GMS Configuration Settings.

To avoid the need to restart the DAS and the cluster, configure the GMS cluster settings during cluster creation as explained in To Create a Cluster.

Changing any GMS settings using the `set` subcommand after cluster creation requires a domain administration server (DAS) and cluster restart as explained here.

1. Ensure that the DAS and cluster are running.

   Remote subcommands require a running server.

2. Use the `get` subcommand to determine the settings to change.

   For example:

       asadmin> get "configs.config.mycfg.group-management-service.*"
       configs.config.mycfg.group-management-service.failure-detection.heartbeat-frequency-in-millis=2000
       configs.config.mycfg.group-management-service.failure-detection.max-missed-heartbeats=3
       configs.config.mycfg.group-management-service.failure-detection.verify-failure-connect-timeout-in-millis=10000
       configs.config.mycfg.group-management-service.failure-detection.verify-failure-waittime-in-millis=1500
       configs.config.mycfg.group-management-service.group-discovery-timeout-in-millis=5000

   For a complete list of the dotted names for these settings, see Dotted Names for GMS Settings.

3. Use the `set` subcommand to change the settings.

   For example:

       asadmin> set configs.config.mycfg.group-management-service.group-discovery-timeout-in-millis=6000

4. Use the `get` subcommand again to confirm that the changes were made.

   For example:

       asadmin> get configs.config.mycfg.group-management-service.group-discovery-timeout-in-millis

5. Restart the DAS.

   For example:

       asadmin> stop-domain domain1

       asadmin> start-domain domain1

6. Restart the cluster.

   For example:

       asadmin> stop-cluster mycluster

       asadmin> start-cluster mycluster

See Also

You can also view the full syntax and options of a subcommand by typing `asadmin help` subcommand at the command line.

### To Check the Health of Instances in a Cluster

The `get-health` subcommand only works when GMS is enabled. This is the quickest way to evaluate the health of a cluster and to detect if cluster is properly operating; that is, all members of the cluster are running and visible to DAS.

If multicast is not enabled for the network, all instances could be running (as shown by the `list-instances` subcommand), yet isolated from each other. The `get-health` subcommand does not show the instances if they are running but cannot discover each other due to multicast not being configured properly. See To Validate That Multicast Transport Is Available for a Cluster.

1. Ensure that the DAS and cluster are running.

   Remote subcommands require a running server.

2. Check whether server instances in a cluster are running by using the `get-health` subcommand.

Example 4-1 Checking the Health of Instances in a Cluster

This example checks the health of a cluster named `cluster1`.

    asadmin> get-health cluster1
    instance1 started since Wed Sep 29 16:32:46 EDT 2010
    instance2 started since Wed Sep 29 16:32:45 EDT 2010
    Command get-health executed successfully.

See Also

You can also view the full syntax and options of the subcommand by typing `asadmin help get-health` at the command line.

### To Validate That Multicast Transport Is Available for a Cluster

Before You Begin

To test a specific multicast address, multicast port, or bind interface address, get this information beforehand using the `get` subcommand. Use the following subcommand to get the multicast address and port for a cluster named `c1`:

    asadmin> get clusters.cluster.c1
    clusters.cluster.c1.config-ref=mycfg
    clusters.cluster.c1.gms-bind-interface-address=${GMS-BIND-INTERFACE-ADDRESS-c1}
    clusters.cluster.c1.gms-enabled=true
    clusters.cluster.c1.gms-multicast-address=228.9.174.162
    clusters.cluster.c1.gms-multicast-port=5383
    clusters.cluster.c1.name=c1

Use the following subcommand to get the bind interface address of a server instance named `i1`that belongs to a cluster named `c1`, if this system property has been set:

    asadmin> get servers.server.i1.system-property.GMS-BIND-INTERFACE-ADDRESS-c1
    servers.server.i1.system-property.GMS-BIND-INTERFACE-ADDRESS-c1.name=GMS-BIND-INTERFACE-ADDRESS-c1
    servers.server.i1.system-property.GMS-BIND-INTERFACE-ADDRESS-c1.value=10.12.152.30

For information on how to set this system property, see Using the Multi-Homing Feature With GMS.

Note:

Do not run the `validate-multicast` subcommand using the DAS and cluster's multicast address and port values while the DAS and cluster are running. Doing so results in an error.

The `validate-multicast` subcommand must be run at the same time on two or more machines to validate whether multicast messages are being received between the machines.

Check whether multicast transport is available for a cluster by using the `validate-multicast` subcommand.

Example 4-2 Validating That Multicast Transport Is Available for a Cluster

This example checks whether multicast transport is available for a cluster named `c1`.

Run from host `sr1`:

    asadmin> validate-multicast
    Will use port 2048
    Will use address 228.9.3.1
    Will use bind interface null
    Will use wait period 2,000 (in milliseconds)

    Listening for data...
    Sending message with content "sr1" every 2,000 milliseconds
    Received data from sr1 (loopback)
    Received data from sr2
    Exiting after 20 seconds. To change this timeout, use the --timeout command line option.
    Command validate-multicast executed successfully.

Run from host `sr2`:

    asadmin> validate-multicast
    Will use port 2048
    Will use address 228.9.3.1
    Will use bind interface null
    Will use wait period 2,000 (in milliseconds)

    Listening for data...
    Sending message with content "sr2" every 2,000 milliseconds
    Received data from sr2 (loopback)
    Received data from sr1
    Exiting after 20 seconds. To change this timeout, use the --timeout command line option.
    Command validate-multicast executed successfully.

Next Steps

As long as all machines see each other, multicast is validated to be working properly across the machines. If the machines are not seeing each other, set the `--bindaddress` option explicitly to ensure that all machines are using interface on same subnet, or increase the `--timetolive` option from the default of `4`. If these changes fail to resolve the multicast issues, ask the network administrator to verify that the network is configured so the multicast messages can be seen between all the machines used to run the cluster.

See Also

You can also view the full syntax and options of the subcommand by typing `asadmin help get-health` at the command line.

### Discovering a Cluster When Multicast Transport Is Unavailable

When multicast transport is unavailable, GlassFish Server instances that are joining a cluster cannot rely on broadcast messages from GMS to discover the cluster. Instead, an instance that is joining a cluster uses a running instance or the DAS in the cluster to discover the cluster.

Therefore, when multicast transport is unavailable, you must provide the locations of instances in the cluster to use for discovering the cluster. You are not required to provide the locations of all instances in the cluster. However, for an instance to discover the cluster, at least one instance whose location you provide must be running. To increase the probability of finding a running instance, provide the locations of several instances.

If the DAS will be left running after the cluster is started, provide the location of the DAS first in the list of instances. When a cluster is started, the DAS is running before any of the instances in the cluster are started.

The locations of the instances to use for discovering a cluster are part of the configuration data that you provide when creating the cluster. How to provide this data depends on how instances are distributed, as explained in the following subsections:

- To Discover a Cluster When Multiple Instances in a Cluster are Running on a Host

- To Discover a Cluster When Each Instance in a Cluster Is Running on a Different Host

#### To Discover a Cluster When Multiple Instances in a Cluster are Running on a Host

If multiple instances in the same cluster are running on a host, you must provide a list of uniform resource indicators (URIs). Each URI must locate a GlassFish Server instance or the DAS in the cluster.

1. Ensure that the DAS is running.

   Remote subcommands require a running server.

2. Create a system property to represent the port number of the port on which the DAS listens for messages from GMS for the cluster.

   Use the `create-system-properties` subcommand for this purpose.

       asadmin> create-system-properties GMS_LISTENER_PORT-cluster-name=gms-port

   cluster-name

     The name of the cluster to which the messages from GMS apply.

   gms-port

     The port number of the port on which the DAS listens for messages from GMS.

3. Restart the DAS.

4. When creating the cluster, set the `GMS_DISCOVERY_URI_LIST` property to a comma-separated list of URIs that locate instances to use for discovering the cluster.

       asadmin> create-cluster --properties GMS_DISCOVERY_URI_LIST=uri-list cluster-name

   uri-list

     A comma-separated list of URIs that locate a GlassFish Server instance or the DAS in the cluster.

     The format of each URI in the list is as follows:

     scheme`://`host-name-or -IP-address`:`port

     - scheme is the URI scheme, which is `tcp`.

     - host-name-or -IP-address is the host name or IP address of the host on which the instance is running.

     - port is the port number of the port on which the instance will listen for messages from GMS.

   cluster-name

     The name of the cluster that you are creating.

   Note:

   For complete instructions for creating a cluster, see To Create a Cluster.

5. When you add each instance to the cluster, set the system property `GMS_LISTENER_PORT-`clustername for the instance.

   - To create the instance centrally, run the following command:

         asadmin> create-instance --node node-name
         --systemproperties GMS_LISTENER_PORT-cluster-name=gms-port --cluster  cluster-name instance-name

   - To create the instance locally, run the following command:

         asadmin> create-local-instance
         --systemproperties GMS_LISTENER_PORT-cluster-name=gms-port --cluster  cluster-name instance-name

   node-name

     The name of an existing GlassFish Server node on which the instance is to reside. For more information about nodes, see Administering GlassFish Server Nodes.

   cluster-name

     The name of the cluster to which the you are adding the instance.

   gms-port

     The port number of the port on which the instance listens for messages from GMS.

   instance-name

     The name of the instance that you are creating.

   Note:

   For full instructions for adding an instance to a cluster, see the following sections:

   - To Create an Instance Centrally

   - To Create an Instance Locally

Example 4-3 Discovering a Cluster When Multiple Instances are Running on a Host

This example creates a cluster that is named `tcpcluster` for which GMS is not using multicast for broadcasting messages.

The cluster contains the instances `instance101` and `instance102`. These instances reside on the host whose IP address is `10.152.23.224` and listen for GMS events on ports 9091 and 9092. The DAS is also running on this host and listens for GMS events on port 9090.

Instances that are joining the cluster will use the DAS and the instances `instance101` and `instance102` to discover the cluster.

    asadmin> create-system-properties GMS_LISTENER_PORT-tcpcluster=9090
    Command create-system-properties executed successfully.
    asadmin> restart-domain
    Successfully restarted the domain
    Command restart-domain executed successfully.
    asadmin> create-cluster --properties GMS_DISCOVERY_URI_LIST=
    tcp'\\:'//10.152.23.224'\\:'9090,
    tcp'\\:'//10.152.23.224'\\:'9091,
    tcp'\\:'//10.152.23.224'\\:'9092 tcpcluster
    Command create-cluster executed successfully.
    asadmin> create-local-instance
    --systemproperties GMS_LISTENER_PORT-tcpcluster=9091 --cluster tcpcluster
    instance101
    Rendezvoused with DAS on localhost:4848.
    Port Assignments for server instance instance101:
    JMX_SYSTEM_CONNECTOR_PORT=28686
    JMS_PROVIDER_PORT=27676
    HTTP_LISTENER_PORT=28080
    ASADMIN_LISTENER_PORT=24848
    JAVA_DEBUGGER_PORT=29009
    IIOP_SSL_LISTENER_PORT=23820
    IIOP_LISTENER_PORT=23700
    OSGI_SHELL_TELNET_PORT=26666
    HTTP_SSL_LISTENER_PORT=28181
    IIOP_SSL_MUTUALAUTH_PORT=23920
    Command create-local-instance executed successfully.
    asadmin> create-local-instance
    --systemproperties GMS_LISTENER_PORT-tcpcluster=9092 --cluster tcpcluster
    instance102
    Rendezvoused with DAS on localhost:4848.
    Using DAS host localhost and port 4848 from existing das.properties for node
    localhost-domain1. To use a different DAS, create a new node using
    create-node-ssh or create-node-config. Create the instance with the new node and
    correct host and port:
    asadmin --host das_host --port das_port create-local-instance --node node_name
    instance_name.
    Port Assignments for server instance instance102:
    JMX_SYSTEM_CONNECTOR_PORT=28687
    JMS_PROVIDER_PORT=27677
    HTTP_LISTENER_PORT=28081
    ASADMIN_LISTENER_PORT=24849
    JAVA_DEBUGGER_PORT=29010
    IIOP_SSL_LISTENER_PORT=23821
    IIOP_LISTENER_PORT=23701
    OSGI_SHELL_TELNET_PORT=26667
    HTTP_SSL_LISTENER_PORT=28182
    IIOP_SSL_MUTUALAUTH_PORT=23921
    Command create-local-instance executed successfully.

See Also

- `create-system-properties`(1)

- To Create a Cluster

- To Create an Instance Centrally

- To Create an Instance Locally

#### To Discover a Cluster When Each Instance in a Cluster Is Running on a Different Host

If all instances in a cluster and the DAS are running on different hosts, you can specify the locations of instances to use for discovering the cluster as follows:

- By specifying a list of host names or Internet Protocol (IP) addresses. Each host name or IP address must locate a host on which the DAS or a GlassFish Server instance in the cluster is running. Instances that are joining the cluster will use the DAS or the instances to discover the cluster.

- By generating the list of locations automatically. The generated list contains the locations of the DAS and all instances in the cluster.

Multiple instances on the same host cannot be members of the same cluster.

1. Ensure that the DAS is running.

   Remote subcommands require a running server.

2. When creating the cluster, set the properties of the cluster as follows:

   - Set the `GMS_DISCOVERY_URI_LIST` property to one of the following values:

     - A comma-separated list of IP addresses or host names on which the DAS or the instances to use for discovering the cluster are running.

       The list can contain a mixture of IP addresses and host names.

     - The keyword `generate`.

   - Set the `GMS_LISTENER_PORT` property to a port number that is unique for the cluster in the domain.

   If you are specifying a list of IP addresses or host names, type the following command:

       asadmin> create-cluster --properties GMS_DISCOVERY_URI_LIST=host-list:
       GMS_LISTENER_PORT=gms-port cluster-name

   If you are specifying the keyword `generate`, type the following command:

       asadmin> create-cluster --properties GMS_DISCOVERY_URI_LIST=generate:
       GMS_LISTENER_PORT=gms-port cluster-name

   host-list

     A comma-separated list of IP addresses or host names on which the DAS or the instances to use for discovering the cluster are running.

   gms-port

     The port number of the port on which the cluster listens for messages from GMS.

   cluster-name

     The name of the cluster that you are creating.

   Note:

   For complete instructions for creating a cluster, see To Create a Cluster.

Example 4-4 Discovering a Cluster by Specifying a List of IP Addresses

This example creates a cluster that is named `ipcluster` for which GMS is not using multicast for broadcasting messages. The instances to use for discovering the cluster are located through a list of IP addresses. In this example, one instance in the cluster is running on each host and the DAS is running on a separate host. The cluster listens for messages from GMS on port 9090.

    asadmin> create-cluster --properties 'GMS_DISCOVERY_URI_LIST=
    10.152.23.225,10.152.23.226,10.152.23.227,10.152.23.228:
    GMS_LISTENER_PORT=9090' ipcluster
    Command create-cluster executed successfully.

Example 4-5 Discovering a Cluster by Generating a List of Locations of Instances

This example creates a cluster that is named `gencluster` for which GMS is not using multicast for broadcasting messages. The list of locations of instances to use for discovering the cluster is generated automatically. In this example, one instance in the cluster is running on each host and the DAS is running on a separate host. The cluster listens for messages from GMS on port 9090.

    asadmin> create-cluster --properties 'GMS_DISCOVERY_URI_LIST=generate:
    GMS_LISTENER_PORT=9090' gencluster
    Command create-cluster executed successfully.

Next Steps

After creating the cluster, add instances to the cluster as explained in the following sections:

- To Create an Instance Centrally

- To Create an Instance Locally

See Also

- To Create a Cluster

- To Create an Instance Centrally

- To Create an Instance Locally

### Using the Multi-Homing Feature With GMS

Multi-homing enables GlassFish Server clusters to be used in an environment that uses multiple Network Interface Cards (NICs). A multi-homed host has multiple network connections, of which the connections may or may not be the on same network. Multi-homing provides the following benefits:

- Provides redundant network connections within the same subnet. Having multiple NICs ensures that one or more network connections are available for communication.

- Supports communication across two or more different subnets. The DAS and all server instances in the same cluster must be on the same subnet for GMS communication, however.

- Binds to a specific IPv4 address and receives GMS messages in a system that has multiple IP addresses configured. The responses for GMS messages received on a particular interface will also go out through that interface.

- Supports separation of external and internal traffic.

#### Traffic Separation Using Multi-Homing

You can separate the internal traffic resulting from GMS from the external traffic. Traffic separation enables you plan a network better and augment certain parts of the network, as required.

Consider a simple cluster, `c1`, with three instances, `i101`, `i102`, and `i103`. Each instance runs on a different machine. In order to separate the traffic, the multi-homed machine should have at least two IP addresses belonging to different networks. The first IP as the external IP and the second one as internal IP. The objective is to expose the external IP to user requests, so that all the traffic from the user requests would be through them. The internal IP is used only by the cluster instances for internal communication through GMS. The following procedure describes how to set up traffic separation.

To configure multi-homed machines for GMS without traffic separation, skip the steps or commands that configure the `EXTERNAL-ADDR` system property, but perform the others.

To avoid having to restart the DAS or cluster, perform the following steps in the specified order.

To set up traffic separation, follow these steps:

1. Create the system properties `EXTERNAL-ADDR` and `GMS-BIND-INTERFACE-ADDRESS-c1` for the DAS.

   - `asadmin create-system-properties` `target` `server EXTERNAL-ADDR=192.155.35.4`

   - `asadmin create-system-properties` `target` `server GMS-BIND-INTERFACE-ADDRESS-c1=10.12.152.20`

2. Create the cluster with the default settings.

   Use the following command:

       asadmin create-cluster c1

   A reference to a system property for GMS traffic is already set up by default in the `gms-bind-interface-address` cluster setting. The default value of this setting is `${GMS-BIND-INTERFACE-ADDRESS-`cluster-name`}`.

3. When creating the clustered instances, configure the external and GMS IP addresses.

   Use the following commands:

   - `asadmin create-instance` `node` `localhost` `cluster` `c1` `systemproperties` `EXTERNAL-ADDR=192.155.35.5:GMS-BIND-INTERFACE-ADDRESS-c1=10.12.152.30 i101`

   - `asadmin create-instance` `node` `localhost` `cluster` `c1` `systemproperties` `EXTERNAL-ADDR=192.155.35.6:GMS-BIND-INTERFACE-ADDRESS-c1=10.12.152.40 i102`

   - `asadmin create-instance` `node` `localhost` `cluster` `c1` `systemproperties` `EXTERNAL-ADDR=192.155.35.7:GMS-BIND-INTERFACE-ADDRESS-c1=10.12.152.50 i103`

4. Set the address attribute of HTTP listeners to refer to the `EXTERNAL-ADDR` system properties.

   Use the following commands:

       asadmin set c1-config.network-config.network-listeners.network-listener.http-1.address=\${EXTERNAL-ADDR}
       asadmin set c1-config.network-config.network-listeners.network-listener.http-2.address=\${EXTERNAL-ADDR}

## Creating, Listing, and Deleting Clusters

GlassFish Server enables you to create clusters, obtain information about clusters, and delete clusters that are no longer required.

The following topics are addressed here:

- To Create a Cluster

- To List All Clusters in a Domain

- To Delete a Cluster

### To Create a Cluster

Use the `create-cluster` subcommand in remote mode to create a cluster.

To ensure that the GMS can detect changes in cluster membership, a cluster's GMS settings must be configured correctly. To avoid the need to restart the DAS and the cluster, configure a cluster's GMS settings when you create the cluster. If you change GMS settings for an existing cluster, the DAS and the cluster must be restarted to apply the changes.

When you create a cluster, GlassFish Server automatically creates a Message Queue cluster for the GlassFish Server cluster. For more information about Message Queue clusters, see Using Message Queue Broker Clusters With GlassFish Server.

Before You Begin

If the cluster is to reference an existing named configuration, ensure that the configuration exists. For more information, see To Create a Named Configuration. If you are using a named configuration to preconfigure GMS settings, ensure that these settings have the required values in the named configuration. For more information, see To Preconfigure Nondefault GMS Configuration Settings.

If you are configuring the cluster's GMS settings when you create the cluster, ensure that you have the following information:

- The address on which GMS listens for group events

- The port number of the communication port on which GMS listens for group events

- The maximum number of iterations or transmissions that a multicast message for GMS events can experience before the message is discarded

- The lowest port number in the range of ports from which GMS selects a TCP port on which to listen

- The highest port number in the range of ports from which GMS selects a TCP port on which to listen

If the DAS is running on a multihome host, ensure that you have the Internet Protocol (IP) address of the network interface on the DAS host to which GMS binds.

1. Ensure that the DAS is running.

   Remote subcommands require a running server.

2. Run the `create-cluster` subcommand.

   Note:

   Only the options that are required to complete this task are provided in this step. For information about all the options for configuring the cluster, see the `create-cluster`(1) help page.

   - If multicast transport is available, run the `create-cluster` subcommand as follows:

         asadmin> create-cluster --config configuration
         --multicastaddress multicast-address --multicastport multicast-port
         --properties GMS_MULTICAST_TIME_TO_LIVE=max-iterations:
         GMS_TCPSTARTPORT=start-port:GMS_TCPENDPORT=end-port cluster-name

   - If multicast transport is not available, run the `create-cluster` subcommand as follows:

         asadmin> create-cluster --config configuration
         --properties GMS_DISCOVERY_URI_LIST=discovery-instances:
         GMS_LISTENER_PORT=gms-port
         cluster-name

   configuration

     An existing named configuration that the cluster is to reference.

   multicast-address

     The address on which GMS listens for group events.

   multicast-port

     The port number of the communication port on which GMS listens for group events.

   max-iterations

     The maximum number of iterations or transmissions that a multicast message for GMS events can experience before the message is discarded.

   discovery-instances

     Instances to use for discovering the cluster. For more information, see Discovering a Cluster When Multicast Transport Is Unavailable.

   gms-port

     The port number of the port on which the cluster listens for messages from GMS.

   start-port

     The lowest port number in the range of ports from which GMS selects a TCP port on which to listen. The default is 9090.

   end-port

     The highest port number in the range of ports from which GMS selects a TCP port on which to listen. The default is 9200.

   cluster-name

     Your choice of name for the cluster that you are creating.

3. If necessary, create a system property to represent the IP address of the network interface on the DAS host to which GMS binds.

   This step is necessary only if the DAS is running on a multihome host.

       asadmin> create-system-properties
       GMS-BIND-INTERFACE-ADDRESS-cluster-name=das-bind-address

   cluster-name

     The name that you assigned to the cluster in Step 2.

   das-bind-address

     The IP address of the network interface on the DAS host to which GMS binds.

Example 4-6 Creating a Cluster for a Network in Which Multicast Transport Is Available

This example creates a cluster that is named `ltscluster` for which port 1169 is to be used for secure IIOP connections. Because the `--config` option is not specified, the cluster references a copy of the named configuration `default-config` that is named `ltscluster-config`. This example assumes that multicast transport is available.

    asadmin> create-cluster
    --systemproperties IIOP_SSL_LISTENER_PORT=1169
    ltscluster
    Command create-cluster executed successfully.

Example 4-7 Creating a Cluster and Setting GMS Options for a Network in Which Multicast Transport Is Available

This example creates a cluster that is named `pmdcluster`, which references the existing configuration `clusterpresets` and for which the cluster's GMS settings are configured as follows:

- GMS listens for group events on address 228.9.3.1 and port 2048.

- A multicast message for GMS events is discarded after 3 iterations or transmissions.

- GMS selects a TCP port on which to listen from ports in the range 10000-10100.

This example assumes that multicast transport is available.

    asadmin> create-cluster --config clusterpresets
    --multicastaddress 228.9.3.1 --multicastport 2048
    --properties GMS_MULTICAST_TIME_TO_LIVE=3:
    GMS_TCPSTARTPORT=10000:GMS_TCPENDPORT=10100 pmdcluster
    Command create-cluster executed successfully.

Next Steps

After creating a cluster, you can add GlassFish Server instances to the cluster as explained in the following sections:

- To Create an Instance Centrally

- To Create an Instance Locally

See Also

- To Create a Named Configuration

- To Preconfigure Nondefault GMS Configuration Settings

- Using Message Queue Broker Clusters With GlassFish Server

- `create-cluster`(1)

- `create-system-properties`(1)

You can also view the full syntax and options of the subcommands by typing the following commands at the command line:

- `asadmin help create-cluster`

- `asadmin help create-system-properties`

### To List All Clusters in a Domain

Use the `list-clusters` subcommand in remote mode to obtain information about existing clusters in a domain.

1. Ensure that the DAS is running.

   Remote subcommands require a running server.

2. Run the `list-clusters` subcommand.

       asadmin> list-clusters

Example 4-8 Listing All Clusters in a Domain

This example lists all clusters in the current domain.

    asadmin> list-clusters
    pmdclust not running
    ymlclust not running
    Command list-clusters executed successfully.

Example 4-9 Listing All Clusters That Are Associated With a Node

This example lists the clusters that contain an instance that resides on the node `sj01`.

    asadmin> list-clusters sj01
    ymlclust not running
    Command list-clusters executed successfully.

See Also

`list-clusters`(1)

You can also view the full syntax and options of the subcommand by typing `asadmin help list-clusters` at the command line.

### To Delete a Cluster

Use the `delete-cluster` subcommand in remote mode to remove a cluster from the DAS configuration.

If the cluster's named configuration was created automatically for the cluster and no other clusters or unclustered instances refer to the configuration, the configuration is deleted when the cluster is deleted.

Before You Begin

Ensure that following prerequisites are met:

- The cluster that you are deleting is stopped. For information about how to stop a cluster, see To Stop a Cluster.

- The cluster that you are deleting contains no GlassFish Server instances. For information about how to remove instances from a cluster, see the following sections:

  - To Delete an Instance Centrally

  - To Delete an Instance Locally

1. Ensure that the DAS is running.

   Remote subcommands require a running server.

2. Confirm that the cluster is stopped.

       asadmin> list-clusters cluster-name

   cluster-name

     The name of the cluster that you are deleting.

3. Confirm that the cluster contains no instances.

       asadmin> list-instances cluster-name

   cluster-name

     The name of the cluster that you are deleting.

4. Run the `delete-cluster` subcommand.

       asadmin> delete-cluster cluster-name

   cluster-name

     The name of the cluster that you are deleting.

Example 4-10 Deleting a Cluster

This example confirms that the cluster `adccluster` is stopped and contains no instances and deletes the cluster `adccluster`.

    asadmin> list-clusters adccluster
    adccluster not running
    Command list-clusters executed successfully.
    asadmin> list-instances adccluster
    Nothing to list.
    Command list-instances executed successfully.
    asadmin> delete-cluster adccluster
    Command delete-cluster executed successfully.

See Also

- To Stop a Cluster

- To Delete an Instance Centrally

- To Delete an Instance Locally

- `delete-cluster`(1)

- `list-clusters`(1)

- `list-instances`(1)

You can also view the full syntax and options of the subcommands by typing the following commands at the command line:

- `asadmin help delete-cluster`

- `asadmin help list-clusters`

- `asadmin help list-instances`