VERITAS Volume Manager 3.5 Administrator's Guide (September 2004)

Administering Cluster Functionality

Introduction

Chapter 10338

Introduction

A cluster consists of a number of hosts or nodes that share a set of disks.

The main beneﬁts of cluster conﬁgurations are:

• Availability—If one node fails, the other nodes can still access the

shared disks. When conﬁgured with suitable software,

mission-critical applications can continue running by transferring

their execution to a standby node in the cluster. This ability to

provide continuous uninterrupted service by switching to redundant

hardware is commonly termed failover.

Failover is transparent to users and high-level applications for

database and ﬁle-sharing. You must conﬁgure cluster management

software

• Off-host processing—Clusters can reduce contention for system

resources by performing activities such as backup, decision support

and report generation on the more lightly loaded nodes of the cluster.

This allows businesses to derive enhanced value from their

investment in cluster systems.

The cluster functionality of Volume Manager (VxVM) allows up to 16

nodes in a cluster to simultaneously access and manage a set of disks

under VxVM control (VM disks). The same logical view of disk

conﬁguration and any changes to this is available on all the nodes. When

the cluster functionality is enabled, all the nodes in the cluster can share

VxVM objects. This chapter discusses the cluster functionality that is

provided with VxVM.

NOTE You need an additional license to use this feature.

This chapter does not discuss VERITAS Cluster File System nor

cluster management software. See the documentation provided with

these products for more information about them.

For additional information about using the Dynamic Multipathing

(DMP) feature of VxVM in a clustered environment, see “DMP in a

Clustered Environment” on page 129.