Chapter 7

Clustering Servers

7-49

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Network Load Balancing works by creating a virtual network adapter with IP and

MAC addresses that represent the cluster as a single unit.

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When NLB is running in unicast mode, ordinary communication between cluster

servers is impossible. In multicast mode, the cluster servers can communicate

normally.

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Although NLB and server clusters can both function with a single network inter-

face adapter installed in each server, using multiple adapters in each server can

prevent network performance degradation.

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A server cluster requires a storage resource shared by the nodes in the cluster.

Windows Server 2003 supports shared SCSI and Fibre Channel arbitrated loop for

two-node clusters, and Fibre Channel switched fabric for server clusters with more

than two nodes.

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In a server cluster, the quorum is a storage resource that contains cluster configu-

ration data, which nodes use to create their configuration databases as they join

the cluster.

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You can configure a cluster to use various failover policies by specifying which

nodes are permitted to run various cluster resources. Some of the policies include

failover pairs, hot-standby servers, N+I, and failover rings.

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To create and manage server clusters, you use the Cluster Administrator applica-

tion. To manage Network Load balancing clusters, you use Network Load Balanc-

ing Manager.

Exam Highlights

Before taking the exam, review the key points and terms that are presented below to

help you identify topics you need to review. Return to the lessons for additional prac-

tice, and review the “Further Reading” sections in Part 2 for pointers to more informa-

tion about topics covering the exam objectives.

Key Points

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Server clusters are for stateful applications, such as database servers, that have fre-

quently changing data. NLB clusters are for stateless applications, such as Web

servers, in which the data seldom changes.

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While both types of clusters can benefit from multiple network interface adapt-

ers, only server clusters require additional hardware, in the form of a shared

storage solution that enables all the servers in the cluster to access the same

application data.

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All Windows Server 2003 versions support NLB clusters, but only Enterprise Edi-

tion and Datacenter Edition support server clusters.