Overview Of Novell Cluster Services; Why Should I Use Clusters; Benefits Of Novell Cluster Services - Novell OPEN ENTERPRISE SERVER 2 SP 2 - CLUSTER SERVICES 1.8.7 FOR LINUX Manual

Table of Contents

Overview of Novell Cluster

Services

Novell

Cluster Services

manageability of critical network resources including data, applications, and services. It is a multi-

node clustering product for Linux* that is enabled for Novell eDirectory

failback, and migration (load balancing) of individually managed cluster resources.

Section 1.1, "Why Should I Use Clusters?," on page 15

Section 1.2, "Benefits of Novell Cluster Services," on page 15

Section 1.3, "Product Features," on page 16

Section 1.4, "Clustering for High-Availability," on page 16

Section 1.5, "Shared Disk Scenarios," on page 18

1.1 Why Should I Use Clusters?

A server cluster is a group of redundantly configured servers that work together to provide highly

available access for clients to important applications, services, and data while reducing unscheduled

outages. The applications, services, and data are configured as cluster resources that can be failed

over or cluster migrated between servers in the cluster. For example, when a failure occurs on one

node of the cluster, the clustering software gracefully relocates its resources and current sessions to

another server in the cluster. Clients connect to the cluster instead of an individual server, so users

are not aware of which server is actively providing the service or data. In most cases, users are able

to continue their sessions without interruption.

Each server in the cluster runs the same operating system and applications that are needed to provide

the application, service, or data resources to clients. Shared devices are connected to and mounted

on only one server at a time. Clustering software monitors the health of each of the member servers

by listening for its heartbeat, a simple message that lets the others know it is alive.

The cluster's virtual server provides a single point for accessing, configuring, and managing the

cluster servers and resources. The virtual identity is bound to the cluster's master node and remains

with the master node regardless of which member server acts the master node. The master server

also keeps information about each of the member servers and the resources they are running. If the

master server fails, the control duties are passed to another server in the cluster.

1.2 Benefits of Novell Cluster Services

Novell Cluster Services provides high availability from commodity components. You can configure

up to 32 OES 2 Linux servers in a high-availability cluster, where resources can be dynamically

relocated to any server in the cluster. Resources can be configured to automatically fail over to one

or multiple different preferred servers in the event of a server failure. In addition, costs are lowered

through the consolidation of applications and operations onto a cluster.

Novell Cluster Services allows you to manage a cluster from a single point of control and to adjust

resources to meet changing workload requirements (thus, manually "load balance" the cluster).

Resources can also be cluster migrated manually to allow you to troubleshoot hardware. For

is a server clustering system that ensures high availability and

and supports failover,