Node


 

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A node is a logical grouping of managed servers corresponding to a logical or physical computer system with a distinct IP host address. Nodes cannot span multiple computers. By default, node names are based on the host name of the computer, for example MyHostNode01.

Unlike a managed node, an unmanaged node does not employ node or administrative agents. App and Web servers can be on unmanaged or managed nodes. A stand-alone appserver is an unmanaged node. The appserver node becomes a managed node when it is either federated into a cell or registered with an administrative agent.

By creating a managed node through federating the appserver node into a dmgr cell, a node agent is automatically created. The node agent process manages the appserver configurations and servers on the node.

When creating a managed node by registering an appserver node with an administrative agent, the appserver must be an unfederated appserver node. The administrative agent is a single interface that monitors and controls one or more appserver nodes so that we can use the appservers only to run the applications. Using a single interface reduces the overhead of running admin services on every standalone appserver.

A managed node in a cell can have...

A managed node not in a cell, but is instead registered to an administrative agent, can have...

An unmanaged node can exist in a cell as long as the unmanaged node only has a supported Web server defined on it. Unsupported Web servers can be on unmanaged nodes only and cannot be in a cell.

Use the command line only to create a managed node that is registered to an administrative agent.

We can create a managed node in a cell using...

Each of these methods for adding a node to an ND cell includes the option of specifying a target node group for the managed node to join. If we do not specify a node group, or you do not have the option of specifying a node group, the default node group of DefaultNodeGroup is the target node group.

Whether you specify an explicit node group for a cell or accept the default, the node group membership rules must be satisfied. If the node that we are adding does not satisfy the node group membership rules for the target node group, the add node operation fails with an error message.

Each managed node that is joined to a cell must be a member of a node group. However, a managed node that is registered to an administrative agent cannot be a member of a node group.

The concepts of managed and unmanaged nodes are not applied to the registration of nodes to the job manager.

Administrative functions for Web server nodes

WAS supports basic admin functions for all supported Web servers. For example, the generation of a plug-in configuration can be performed for all Web servers. However, propagation of a plug-in configuration to remote Web servers is supported only for IBM HTTP Servers defined on an unmanaged node. If the Web server is defined on a managed node, propagation of the plug-in configuration is done for all the Web servers by using node synchronization. The Web server plug-in configuration file is created according to the Web server definition and is based on the list of applications that are deployed on the Web server. We can also map all supported Web servers as potential targets for the modules during application deployment.

WAS supports some additional admin console tasks for IBM HTTP Servers on managed and unmanaged nodes. For instance, we can start IBM HTTP Servers, stop them, terminate them, display their log files, and edit their configuration files.


Related concepts

Node group
Administrative agent
Manage nodes
Set up the admin architecture
Communicating with Web servers
Install IBM HTTP Server
Manage node group members