4 WebLogic Server Clusters
A cluster appears to clients to be a single WebLogic Server instance. The server instances that constitute a cluster can run on the same machine, or be located on different machines. You can increase a cluster's capacity by adding additional server instances to the cluster on an existing machine, or you can add machines to the cluster to host the incremental server instances. Each server instance in a cluster must run the same version of WebLogic Server.
For more information on clusters, see Administering Clusters for Oracle WebLogic Server.
Note:
If you are logged into a domain partition, navigate from the Domain Partition menu. Note that WebLogic Server Multitenant domain partitions, resource groups, resource group templates, and virtual targets are deprecated in WebLogic Server 12.2.1.4.0 and will be removed in the next release.
This chapter includes the following sections:
Create clusters
This section describes how to create new clusters. This section includes the following tasks:
Create a new configured cluster
A configured cluster is a cluster in which you manually configure and add each server instance.
To create a new configured cluster:
Cluster Properties
On the Cluster Properties page, define the general cluster properties for your new configured cluster:
-
Name: enter a unique name for your configured cluster.
-
Messaging Mode: select the messaging mode you want to use for this cluster.
-
Unicast Broadcast Channel: if you are using the unicast messaging mode, enter the unicast broadcast channel. This channel is used to transmit messages with the cluster. If you do not specify a channel, then the default channel is used.
-
Multicast Address: if you are using the multicast messaging mode, enter the multicast address of the new configured cluster. A multicast address is an IP address in the range from 224.0.0.0 to 239.255.255.255. The valid range is from 224.0.0.0 to 239.255.255.255. The default value used by WebLogic Server is 239.192.0.0. You should avoid using multicast addresses in the range x.0.0.1. This address must be unique to this cluster and should not be shared by other applications.
-
Multicast Port: if you are using the multicast messaging mode, enter the multicast port of the new configured cluster.The multicast port is used by cluster members to communicate with each other. Valid values are between 1 and 65535.
For more information about these fields, see Configuration Options.
Add Servers
On the Add Servers page, you can optionally add one or more servers to the new configured cluster by moving the servers from the Available column into the Chosen column.
For more information about these fields, see Configuration Options.
Review
On the Review page, review the configuration for your new configured cluster.
For more information about these fields, see Configuration Options.
Create a new dynamic cluster
A dynamic cluster is a cluster that contains one or more generated (dynamic) server instances that are based on a single shared server template.
To create a new dynamic cluster:
Cluster Properties
On the Cluster Properties page, define the general cluster properties for your new dynamic cluster:
-
Name: enter a unique name for your dynamic cluster.
-
Messaging Mode: select the messaging mode you want to use for this cluster.
-
Unicast Broadcast Channel: if you are using the unicast messaging mode, enter the unicast broadcast channel. This channel is used to transmit messages with the cluster. If you do not specify a channel, then the default channel is used.
-
Multicast Address: if you are using the multicast messaging mode, enter the multicast address of the new dynamic cluster. A multicast address is an IP address in the range from 224.0.0.0 to 239.255.255.255. The valid range is from 224.0.0.0 to 239.255.255.255. The default value used by WebLogic Server is 239.192.0.0. You should avoid using multicast addresses in the range x.0.0.1. This address must be unique to this cluster and should not be shared by other applications.
-
Multicast Port: if you are using the multicast messaging mode, enter the multicast port of the new configured cluster.The multicast port is used by cluster members to communicate with each other. Valid values are between 1 and 65535.
For more information about these fields, see Configuration Options.
Dynamic Server Properties
On the Dynamic Server Properties page, define the dynamic server properties for your new dynamic cluster:
-
Dynamic Cluster Size: Enter the initial number of dynamic server instances provisioned for your new dynamic cluster.
Note:
If you expand the cluster, the Dynamic Cluster Size must not exceed the limit set in Maximum Dynamic Cluster Size. -
Max Dynamic Cluster Size: Enter the maximum number of running dynamic server instances allowed for scale up operations in this dynamic cluster. This number is the sum of the Dynamic Cluster Size and the additional number of dynamic server instances allowed for scale up operations.
-
Server Name Prefix: Specify the naming convention you want to use for the dynamic servers in your dynamic cluster.
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Select either Create a New Server Template Using Domain Defaults or Clone an Existing Server Template For This Cluster. If you choose to clone an existing template, then select the template in Server Template to Clone. Server templates are used to configure the characteristics that are common to all the server instances in your dynamic cluster. If you do not have any server templates configured, then one is automatically generated for you.
For more information about these fields, see Configuration Options.
Machine Bindings
On the Machine Bindings page, s elect the method you want to use to distribute the dynamic servers in your dynamic cluster across machines. Select Use any machine configured in this domain, Use a single machine for all dynamic servers, or Use a subset of machines in this domain. If you choose Use a single machine for all dynamic servers, then select the machine you want to use from the Selected Machine menu. If you choose Use a subset of machines in this domain, then enter the machine name match expression in Machine Name Match Expression.
For more information about these fields, see Configuration Options.
Listen Port Bindings
On the Listen Port Bindings page, select how the dynamic servers should be bound to listen ports. Listen ports for dynamic servers can be specified in a server template or can be dynamically generated to be unique.
-
Select Assign each dynamic server unique listen ports to create unique listen ports for each dynamic server. Enter the desired listen port and SSL listen port for the first dynamic server instance in Listen Port for First Server and SSL Listen Port for First Server.
Enter the desired base administration port number in Base Administration Port.
-
Select Assign each dynamic server fixed listen ports to assign the same listen port and SSL listen port for all dynamic servers. Enter the desired listen port and SSL listen port in Listen Port and SSL Listen Port.
Enter the desired administration port number in Administration Port.
For more information about these fields, see Configuration Options.
Review
On the Review page, review the configuration for your new dynamic cluster.
For more information about these fields, see Configuration Options.
Monitor clusters
This section describes how to monitor clusters. This section includes the following tasks:
Monitor status of all clusters
To monitor the runtime status of all clusters configured in a domain:
Monitor the status of server instances in a cluster
To monitor the status of servers in a cluster:
Optionally, select View to access the following table options:
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Columns: add or remove the columns displayed in the table
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Detach: detach the table (viewing option)
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Sort: sort the columns in ascending or descending order
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Reorder: change the order of the columns displayed
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Query by Example
Monitor server instances in a cluster
To monitor the server instances in a cluster:
Optionally, select View to access the following table options:
-
Columns: add or remove the columns displayed in the table
-
Sort: sort the columns in ascending or descending order
-
Reorder: change the order of the columns displayed
-
Query by Example
Monitor cluster JDBC data sources
To monitor the JDBC data sources associated with a specific cluster:
Monitor cluster failover
To monitor failover information for a cluster:
Optionally, select View to access the following table options:
-
Columns: add or remove the columns displayed in the table
-
Detach: detach the table (viewing option)
-
Sort: sort the columns in ascending or descending order
-
Reorder: change the order of the columns displayed
-
Query by Example
Monitor cluster asynchronous tasks
Because some administrative tasks (such as deployments, service migrations, and attempts to start or stop Managed Servers) are completed immediately and others take varying amounts of time to complete, the Asynchronous Tasks summary page allows you to monitor the completion status of all tasks.
To monitor the status of asynchronous tasks in a cluster:
Control clusters
This section describes how to control clusters. This section includes the following topics:
Control clusters in a domain
You can start, resume, suspend, or shutdown the server instances assigned to a cluster. For information on how the servers in a cluster transition from STANDBY
or ADMIN
to the RUNNING
state, see Understanding Server Life Cycle in Administering Server Startup and Shutdown for Oracle WebLogic Server.
Before you begin:
Control operations on Managed Servers require starting the Node Manager. Starting Managed Servers in Standby mode requires the domain-wide administration port.
To control the server instances in the clusters configured in a domain:
Optionally, click Create to create a new cluster. For more information on creating clusters, see Create clusters.
Control server instances in a cluster
You can start, resume, suspend, or shutdown the server instances assigned to a cluster. For information on how the servers in a cluster transition from STANDBY
or ADMIN
to the RUNNING
state, see Understanding Server Life Cycle in Administering Server Startup and Shutdown for Oracle WebLogic Server.
Before you begin:
Control operations on Managed Servers require starting the Node Manager. Starting Managed Servers in Standby mode requires the domain-wide administration port.
To control the server instances in a cluster:
Configure clusters
This section describes how to configure clusters. This section includes the following tasks:
Configure cluster messaging
Clusters use messaging for sharing session, load balancing and failover, JMS, and other information between cluster members. Clusters can use either unicast or multicast messaging. Multicast is a simple broadcast technology that enables multiple applications to subscribe to a given IP address and port number and listen for messages, but requires hardware configuration and support. Unicast does not have these requirements.
To configure messaging for a cluster:
Configure cluster migration
If a clustered server fails, then Node Manager can automatically restart the server instance and its services on another machine. You can specify the machines where Node Manager can restart migratable servers and also the data source used during server migration.
To configure server migration in a cluster:
Configure cluster singleton services
This section describes how to configure and control singleton services.
This section includes the following sections:
Configure cluster singleton services general settings
To configure general settings for a cluster singleton service:
Configure cluster singleton services migration
To configure migration for a cluster singleton service:
Configure cluster job scheduling
Job scheduling makes Java CommonJ timers cluster-aware and provides the ability to execute jobs periodically anywhere in a cluster without dependency on a particular server instance.
To configure job scheduling in a cluster:
Configure cluster health monitoring
WebLogic Server provides a self-health monitoring capability to improve the reliability and availability of servers in a WebLogic Server domain. Selected subsystems within each server instance monitor their health status based on criteria specific to the subsystem
To configure health monitoring characteristics for a cluster:
Configure on-demand scaling for a dynamic cluster
To configure on-demand scaling for a dynamic cluster:
- From the WebLogic Domain menu, select Environment, then select Clusters.
- In the Clusters table, select the row of the dynamic cluster you want to scale up or down.
- Click Scale Up/Down.
- On the Scale Up/Down page, use the arrows in the Desired Server Count field to select the number of running server instances you want in your dynamic cluster.
- Click Scale Up/Down.
Configure elasticity for dynamic clusters
Elasticity enables the automatic scaling of dynamic clusters and re-provisioning of associated resources based on demand. Enable elasticity by constructing policies to monitor resource usage and set actions to enable specific scaling or other administrative actions according to those policies. You can configure elasticity to provide on-demand scaling, calendar based scaling, or policy based scaling.
This section includes the following tasks
Monitor elastic policies in a dynamic cluster
An elasticity policy monitors resource utilization in a dynamic cluster to determine scaling decisions, or other administrative actions, such as adding servers to a dynamic cluster or adjusting the size of a JDBC connection pool. When an elasticity policy evaluates to true, the one or more actions associated with that policy are executed.
To monitor the elastic policies configured in a dynamic cluster: