Windows Integrity Cluster Installation and Configuration Guide

Introduction
Server Cluster vs. Network Load Balancing
Chapter 1
9
Server Cluster vs. Network Load Balancing
Windows Server 2003 provides two types of clustering services:
• Server Cluster—Available only in Windows Server 2003, Enterprise Edition or
Datacenter Edition, this service provides high availability and scalability for
mission-critical applications such as databases, messaging systems, and file and
print services. The servers (nodes) in the cluster remain in constant communication.
If one of the nodes becomes unavailable as a result of failure or maintenance, another
node immediately begins providing service, a process known as failover. Users
accessing the service continue to access it, unaware that it is now being provided from
a different node. Both Windows Server 2003, Enterprise Edition and Datacenter
Edition support server cluster configurations of up to 8 nodes.
• Network Load Balancing (NLB)—Available in all editions of Windows Server
2003, this service load balances incoming Internet Protocol (IP) traffic across clusters.
NLB enhances both the availability and scalability of Internet server-based programs
such as Web servers, streaming media servers, and Terminal Services. By acting as
the load balancing infrastructure and providing control information to management
applications built on top of Windows Management Instrumentation (WMI), NLB can
seamlessly integrate into existing Web server farm infrastructures. NLB clusters can
scale to 32 nodes.
Table 1-1 summarizes some of the differences between these two technologies. Additional
differences and considerations are detailed in the following sections.
Table 1-1 Server Cluster vs. Network Load Balancing
Server Cluster NLB
Used for databases, e-mail services,
line of business (LOB) applications,
and custom applications
Used for Web servers, firewalls, and Web
services
Included with Windows Server 2003,
Enterprise Edition, and Windows
Server 2003, Datacenter Edition
Included with all four versions of Windows
Server 2003
Provides high availability and server
consolidation
Provides high availability and scalability
Can be deployed on a single network
or geographically distributed
Generally deployed on a single network but
can span multiple networks if properly
configured
Supports clusters up to eight nodes Supports clusters up to 32 nodes
Requires the use of shared or
replicated storage
Doesn't require any special hardware or
software; works “out of the box”