Advanced Novell Network Management: NetWare 6

Chapter 11: Configure and Test High Availability Services

 

Objectives:

This chapter discusses setting up services on a high availability cluster. The objectives are:

  1. Identify Cluster-Aware and Cluster-Naive Applications
  2. Identify How to Cluster-Enable an Application
  3. Identify How to Assign Nodes to a Resource
  4. Identify How to Set Start, Failover, and Failback Modes
  5. Identify How to View and Edit Load and Unload Scripts
  6. Identify How to Find NCS Configuration and Troubleshooting Information
Concepts:
Identify Cluster-Aware and Cluster-Naive Applications

This chapter begins with some new terms. They are unusual, but understandable:

  • Cluster-aware - an application that "understands" clustering
  • Cluster-naive - an application that can be clustered, but that does not contain programming to make use of clusters.

The chapter offers a list of cluster-aware applications, most of them Novell products:

  • Apache Web Server
  • AppleTalk Filing Protocol (AFP)
  • BorderManager® (Proxy and VPN)
  • DHCP Server
  • Enterprise Web Server (LDAP and NDS)
  • GroupWise 5.5 and 6 (MTA, POA, GWIA, and WebAccess)
  • iFolder
  • iManager
  • iPrint
  • NetWare 5.1 FTP Server
  • NFAP Common Internet File Services (CIFS)
  • NFS 3.0
  • NDPS
  • Novell Clients (Windows 98 and Windows 2000)
  • Oracle database
  • Btrieve®
  • Norton AntiVirus™
  • WebDAV
  • ZENworks for Servers
  • ZENworks for Desktops 2 and 3
Identify How to Cluster-Enable an Application

To cluster-enable an application, you create a resource object for it.

In ConsoleOne, select the cluster object to create the resource in, then choose File, New, Cluster, Cluster Resource. If you are creating a resource that will be based on a template, choose the template. Otherwise, choose Define Additional Properties, and define them.

The procedure to do this in Remote Manager begins with Cluster Config, and New Cluster Resource.

Identify How to Assign Nodes to a Resource

Nodes are assigned to a resource to establish the order in which the resource will failover to those nodes. Use ConsoleOne to assign, unassign, or change nodes assigned to a resource. Select the resource, choose Properties, Node, and Cluster Resource Preferred Nodes. Select nodes, and use the arrows in this interface to assign, unassign, or change priority of assignment.

The same kind of changes can be made in Remote Manager.

Identify How to Set Start, Failover, and Failback Modes

The three actions listed can be set to occur in different ways or modes. Each mode provides an administrator with another choice for how the system will perform:

  • Start - Auto mode allows the resource to start when a server is brought on line. Manual mode requires the resource to be started by an administrator.
  • Failover - Auto mode allows the resource to start on the next server on its node list when its current server fails. Manual mode requires an administrator to start the resource on the next server.
  • Failback - The two modes listed above are available: Auto allows a resource to move back to its preferred server when that server is available. Manual allows the administrator to choose when to failback. Disable mode is also available, which configures the resource to continue running on the node it has moved to, should the original node come back up.

As above, use ConsoleOne and Remote Manager to set these modes.

Identify How to View and Edit Load and Unload Scripts

A script, called a load script, is used to start a resource or mount a volume on a cluster node. Unload scripts are used to unload resources and volumes.

Load scripts can contain any command you would enter at a console command line. You can simulate console input to a command by preceding the input with two less than signs. For example,
<< Y
would stand for entering the letter Y at the console.

A load script can be given a timeout, a time in which it must complete or the resource enters the comatose state. The default value for timeout is ten minuutes (600 seconds).

In ConsoleOne, each resource has a Load Script and Unload Script property. In Remote Manager, these properties can be accessed as well.

Identify How to Find NCS Configuration and Troubleshooting Information

Documenation on configuring and troubleshooting NCS can be found in the Technical Information Documents and Knowledgebase on the Novell web site.