1.0 Introduction to GroupWise 8 and Novell Cluster Services on NetWare

Before implementing GroupWise 8 with Novell Cluster Services, make sure you have a solid understanding of Novell Cluster Services by reviewing the following information resources:

When you review the information resources recommended above, you discover that clustering employs very specialized terminology. The following brief glossary provides basic definitions of clustering terms and relates them to your GroupWise system:

cluster: A grouping of from 2 to 32 NetWare servers configured using Novell Cluster Services so that data storage locations and applications can transfer from one server to another without interrupting their availability to users.

node: A clustered server; in other words, a single NetWare server that is part of a cluster.

resource: An IP address, volume, application, service, and so on, that can function successfully anywhere in the cluster. The volumes where domains and post offices reside are a specific type of cluster resources termed “volume resources.” In this section, the terms “cluster resource” and “volume resource” are used instead of “resource” to avoid confusion with GroupWise resources (such as conference rooms and projectors).

failover: The process of moving cluster resources from a failed node to a functional node so that availability to users is uninterrupted. For example, if the node where the POA is running goes down, the POA and its post office fail over to a secondary node so that users can continue to use GroupWise. When setting up cluster resources, you need to consider what components need to fail over together in order to continue functioning.

fan-out-failover: The configuration where cluster resources from a failed node fail over to different nodes in order to distribute the load from the failed node across multiple nodes. For example, if a node runs a cluster resource consisting of a domain and its MTA, another cluster resource consisting of a post office and its POA, and a third cluster resource for WebAccess, each cluster resource can be configured to fail over separately to different secondary nodes.

failback: The process of returning cluster resources to their preferred node after the situation causing the failover has been resolved. For example, if a POA and its post office fail over to a secondary node, that cluster resource can be configured to fail back to its preferred node when the problem is resolved.

migration: The process of manually moving a cluster resource from its preferred node to a secondary node for the purpose of performing maintenance on the preferred node, temporarily lightening the load on the preferred node, and so on.

shared disk system: The hardware housing the physical disk volumes that are shared among the cluster nodes.

shared volume: A volume in a shared disk system that can be accessed from any cluster node that needs the data stored on it.

cluster-enabled shared volume: A shared volume for which a Volume Resource object has been created in Novell eDirectory. The properties of the Volume Resource object provide load and unload scripts for programs installed on the volume, failover/failback/migration policies for the volume, and the failover path for the volume. Cluster-enabling is highly recommended for GroupWise.

GroupWise volume: As used in this section, a cluster-enabled shared volume that is used for GroupWise, such as for storing a domain, post office, software distribution directory, and so on. This section also uses the terms Internet Agent volume, WebAccess Agent volume, Messenger volume, and gateway volume in a similar manner.

storage area network (SAN): The cluster nodes together with their shared disk system and shared volumes.

virtual server: A logical server, rather than a physical server, to which cluster-enabled shared volumes are tied.

active/active mode: The configuration of a clustered application where the application runs simultaneously on multiple nodes in the cluster. Active/active mode is recommended when the GroupWise MTA, POA, Internet Agent, and WebAccess Agent run in protected memory because protected memory isolates them from each other, even if they are running on the same node.

active/passive mode: The configuration of a clustered application where the application runs on only one node at a time in the cluster. The GroupWise MTA, POA, Internet Agent, and WebAccess Agent must run in active/passive mode if they are not running in protected memory because only one instance of each agent/database combination can be running at the same time in the cluster.