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Chapter 7
Clustering Servers
7-49
■
Network Load Balancing works by creating a virtual network adapter with IP
and
MAC addresses that represent the cluster as a single unit.
■
When NLB is running in unicast mode, ordinary communication between cluster
servers is impossible. In multicast mode, the cluster servers can
communicate
normally.
■
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.
■
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.
■
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.
■
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.
■
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
■
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.
■
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.
■
All Windows Server 2003 versions support NLB clusters, but only Enterprise
Edi-
tion and Datacenter Edition support server clusters.
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