Administrator's Guide Netscape Enterprise Server

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Chapter 6   Managing Server Clusters

This chapter describes the concept of clustering Netscape Enterprise Servers and explains how you can use them to share configurations among servers.

This chapter includes the following sections:

• About Clusters
• Guidelines for Using Server Clusters
• Setting Up a Cluster
• Adding a Server to a Cluster
• Modifying Server Information
• Removing Servers from a Cluster
• Controlling Server Clusters
• Adding Variables

About Clusters

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A cluster is a group of Enterprise Servers that can be administered from a single Administration Server. Each cluster must include one server designated as the Administration Server. If you have more than one cluster, you can administer all clusters from a single "master" Administration Server. The master administration server retrieves the information about all the clusters and provides the interface for managing the Enterprise Servers installed in their respective clusters.

Here are some of the tasks you can accomplish by organizing your servers into clusters:

• Create a central place for administering all Enterprise Servers
• Share one or more configuration files between servers
• Start and stop all servers from one "master" Administration Server
• View the access and error logs for the servers you selected

By clustering your Enterprise Servers, you're able to specify a master Administration Server for administering all of your clusters.

Note	The individual servers can be installed on any computer in a network, but the Administration Server that you designate as the "master" contains information about all clustered servers, and must have access to each cluster's individual Administration Server.

Guidelines for Using Server Clusters

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When you configure a cluster, the master Administration Server containing the information about all clusters communicates with each individual cluster's Administration Server. The administration server for each cluster must be given the same administration user name and password that the master Administration Server will have.

Before you can create a cluster, all of the servers you want to include in the cluster must be installed. For example, if you want three clusters of five Enterprise Servers per cluster, you would need to:

1. Install all of the servers on the computers where they'll run using the same administration user name and password as the master Administration Server.
2. Configure one of the Enterprise Servers in each cluster as the Administration Server.
3. Configure one single cluster's administration server as the master Administration Server for all clusters. It doesn't matter which server you choose as the master administration server.

   Caution	Clusters can only be homogeneous. All servers in the cluster must be either UNIX or Windows NT/Windows 2000. Combining UNIX and Windows NT/Windows 2000 servers in the same cluster may cause the servers to hang or crash.

   

The following list provides some guidelines for configuring groups of servers into clusters:

• Install all of the servers you want to include in a particular cluster prior to creating any clusters.
• Make sure all servers in a cluster are version 6.1 Enterprise Servers.
• Make sure all cluster-specific Administration Servers have the same userid and password as the master administration server. You can use distributed administration to set up multiple administrators on each Administration Server.
• Install servers on any computer in a network, as long as all computers in the cluster are Windows NT/Windows 2000 or UNIX.
• You can designate any cluster-specific Administration Server as the master administration server.
• Make sure the master Administration Server has access to each cluster-specific Administration Server. The master Administration Server retrieves information about all installed Enterprise Servers.
• Make sure all Administration Servers are Enterprise Server version 6.1 and use the same protocol, HTTP or HTTPS. Only Enterprise Server 6.1 servers are supported for addition to clusters.
• If you change the protocol of one Administration Server in a cluster, you must change the protocols for all Administration Servers. Then use the Modify Server interface to modify the individual servers in the cluster.

Setting Up a Cluster

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To set up a Enterprise Server cluster, perform the following steps:

1. Install the Enterprise Servers on the computers you want to include in the cluster.

Make sure the Administration Server for the cluster has a username and password that the master Administration Server can use for authentication. You can do this either by using the default username and password or by setting up distributed administration.
 

2. Install the server that will contain the master Administration Server, making sure the username and password matches the one set in Step 1.
3. Add a server to the cluster list.
4. Administer a remote server by accessing its Server Manager forms from the cluster form or by copying a configuration file from one server in the cluster to another.

Note	After changing the configuration for a remote server, restart the remote server.

Adding a Server to a Cluster

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When you add a server to a cluster, you specify its Administration Server and port number. If that Administration Server contains information about more than one server, all of its servers are added to the cluster. You can remove individual servers later.

Note	If a remote Administration Server contains information about a cluster, the servers in the remote cluster are not added. The master Administration Server adds only those servers that are physically installed on the remote computer.

To add a remote server to a cluster, perform the following steps:

1. Make sure the master Administration Server is tuned on.
2. Access the Administration Server and choose the Cluster Mgmt tab.
3. Click the Add Server link.
4. Choose the protocol that the remote Administration Server uses.
• http for a normal Administration Server
• https for a secure Administration Server
5. Enter the fully qualified domain name as it appears in the magnus.conf file of the remote server in the Admin Server Hostname field.

For example: mktg.example.com
 

6. Enter the port number for the remote Administration Server.
7. Click OK.

Your master Administration Server now attempts to contact the remote server. This can take a few minutes. You will receive a message confirming the server is added to the cluster.
 

8. Click OK.

   Note	If you have two or more servers on different computers that use the same identifier, the server identifier and the hostname for each computer are displayed. When both server identifier and hostnames are the same, the port number is also displayed.

   

Modifying Server Information

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Use the Modify Server option only to update slave administration port information, after it has been changed on the slave server. If you change the port number of a remote Administration Server in your cluster, you also need to modify the information about that Administration Server stored in the cluster. Any other changes to the slave administration server require you to delete the server, and then add it back into the cluster after the changes have been made.

The remote administration servers will not be affected by modification to the master cluster database, unless their files have been transferred through Cluster Control.

To modify information about a server in a cluster, perform the following steps:

1. Go to the master Administration Server and choose the Cluster Mgmt tab.
2. Click the Modify Server link.

All servers appear listed by their unique server identifier.
 

3. Select the server or server to modify by:
• Checking a specific server
• Clicking Select All

Click Reset to undo all selections.
 

4. Enter the new port number.
5. Click OK.

Removing Servers from a Cluster

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To remove a server from the cluster, perform the following steps:

1. Go to the master Administration Server and choose the Cluster Mgmt tab.
2. Click the Remove Server link.
3. Select the remote server or servers to modify by:
• Checking a specific server
• Clicking Select All

Click Reset Selection to undo all selections.
 

4. Click OK.

A message appears confirming that the server is removed from the cluster. You can no longer access the removed server through the cluster; you can only access it now through it's own Administration Server.

Controlling Server Clusters

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Enterprise Server 6.1 allows you to control the remote servers in your cluster by:

• Starting and stopping them
• Viewing their access and error logs
• Transferring configuration files to them.

  Caution	Clusters must be homogeneous. All servers in the cluster must be either UNIX or Windows NT/Windows 2000. Transferring configuration files from a different platform may cause the servers to hang or crash.

  

To control servers within your cluster, perform the following steps:

1. Go to the Server Manager for the master Administration Server, and choose the Cluster Mgmt tab.
2. Click the Cluster Control link.
3. Select the server or servers to control by:
• Checking a specific server
• Clicking Select All to select all of the servers in the cluster

Click Reset Selection to undo all selections.
 

4. Select Start or Stop remote servers from the drop down menu.
5. Select View Access or View Error log records from the drop down menu and enter the number of lines you wish to view.
6. To transfer configuration files:
1. Select the configuration file you want to transfer in the drop down menu
2. Select server you want to transfer it from in the drop down menu
3. Click Transfer.

Adding Variables

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Variables are used when servers in a cluster need to be configured with different values. These values might be macros to define slaves using different port numbers, or plug-ins to define different shlib paths.

Adding variables affects only the master cluster database. The remote administration servers will not be affected unless their files have been transferred through Cluster Control. When variables are defined, the Administration Server can no longer run independently.

To add variables for a remote server within your cluster, perform the following steps:

1. From the master Administration Server, and choose the Cluster Mgmt tab.
2. Click the Add Variables link.
3. Check the specific server you wish to add variables for.
4. In the Name field enter the type of variable you are adding.

For example: `Port'.
 

5. In the Value field enter the value you are adding.

For example: if `Port' is entered in the name field, the value would be the port number.
 

6. Click OK.

A message appears confirming that the server variable has been added.
 

7. Click OK.

The variable must also be added to the server's configuration file you are transferring to the slave. For example:

SERVERPORT $Port if port was the variable added.

You can set variables with different values for each slave in the configuration file.

Once added, variables can also be edited and deleted using the drop-down Option list in the Add Variables page.

© 2001 Sun Microsystems, Inc. Portions copyright 1999, 2002 Netscape Communications Corporation. All rights reserved.

Last Updated August 02, 2002