19.1 HA concepts

Cluster architecture provides a single, globally coherent process and resource management view for the multiple nodes of a cluster. The following figure shows an example of cluster architecture.

Figure 19‒1: Architecture of a high availability cluster

Each node in a cluster connects to one or more public networks and also connects to a private interconnect, representing a communication channel for transmitting data between cluster nodes.

In modern cluster environments, such as Veritas Cluster Server, Symantec Cluster Server, or Windows Server Failover Cluster, applications are represented as compounds of resources, which are simple operations that enable applications to run in a cluster environment. The resources construct an HA resource group, which represents an application running in a cluster environment. The following figure shows an example HA resource group.

Figure 19‒2: Typical HA resource group layout

This manual uses the term HA resource group to designate a set of resources in any cluster environment. Each HA product uses a different name for the HA resource group. The following table lists for each supported HA product the term that equates to HA resource group in this manual.

Table 19‒1: Terminology for HA resource group in the supported HA products
HA product	Abbreviation	Equivalent term for HA resource group
Veritas Cluster Server	VCS	Service group
Symantec Cluster Server	SCS	Service group
Windows Server Failover Cluster	WSFC^#	Resource group
HA Monitor	HA Monitor	Server

#: WSFC is also referred to as MSFC (Microsoft Failover Cluster), but in this manual WSFC is used.

Not all the HA products listed in Table 19-1 are supported by all OSs.

For the supported cluster software and versions, visit Hitachi's home page.

Organization of this section

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