Veritas Volume Manager 5.1 SP1 Administrator"s Guide (5900-1506, April 2011)

Overview of cluster volume management
Over the past several years, parallel applications using shared data access have
become increasingly popular. Examples of commercially available applications
include Oracle Real Application Clusters™ (RAC), Sybase Adaptive Server®, and
Informatica Enterprise Cluster Edition. In addition, the semantics of Network File
System (NFS), File Transfer Protocol (FTP), and Network News Transfer Protocol
(NNTP) allow these workloads to be served by shared data access clusters. Finally,
numerous organizations have developed internal applications that take advantage
of shared data access clusters.
The cluster functionality of VxVM (CVM) works together with the cluster monitor
that is provided by the host operating system. The cluster monitor informs VxVM
of changes in cluster membership. Each node starts up independently and has its
own cluster monitor plus its own copies of the operating system and VxVM/CVM.
When a node joins a cluster, it gains access to shared disk groups and volumes.
When a node leaves a cluster, it loses access to these shared objects. A node joins
a cluster when you issue the appropriate command on that node.
In an HP Serviceguard cluster, a node can join the cluster automatically at boot
time.
Warning: The CVM functionality of VxVM is supported only when used in
conjunction with a cluster monitor that has been configured correctly to work
with VxVM.
Figure 13-1 shows a simple cluster arrangement consisting of four nodes with
similar or identical hardware characteristics (CPUs, RAM and host adapters), and
configured with identical software (including the operating system).
Administering cluster functionality (CVM)
Overview of clustering
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