Exchange Server 2003 Cluster Architecture


Topic Last Modified: 2005-10-23

In Microsoft Windows Server 2003, a server cluster is an arrangement of individual computers that each run the Microsoft Windows Cluster service. The computers that compose the server cluster are connected to each other through a network and a shared disc system. Server clusters have two significant advantages. First, the Cluster service monitors the servers that belong to a cluster. If a service fails on one server, the Cluster service brings it back online quickly by rerouting the service through another server. This helps minimize system downtime. Second, server clusters simplify hardware and software maintenance. You can perform a rolling upgrade by moving cluster resources, often referred to as virtual servers, to alternate nodes and then performing hardware or software upgrades on the original node. You can prevent downtime and simplify system maintenance by deploying Microsoft Exchange Server 2003 in a Windows Server 2003 server cluster.

To install Exchange 2003 in a server cluster with up to eight nodes, you must use Windows Server 2003 Enterprise Edition or Datacenter Edition, and Exchange Server 2003 Enterprise Edition. You can find a feature comparison of the Windows Server 2003 family of products at

This section discusses the Windows Cluster service architecture, and the interaction between Exchange Server 2003 Enterprise Edition and the Windows Cluster service. It includes information on tasks that need to be performed on Exchange servers running in a server cluster. The following topics are discussed in detail:

  • Windows Cluster service architecture   The general characteristics of clustered systems running Windows Server 2003 are discussed in this section. High-availability solutions for Exchange 2003 mailbox servers require an understanding of the Windows Cluster service architecture and how the Cluster service interacts with cluster-aware applications such as Exchange 2003.

  • Exchange Virtual Servers   An Exchange Virtual Server is an instance of Exchange 2003 Enterprise Edition that is configured to run in a server cluster. The characteristics of virtual servers determine how clients connect to Exchange 2003 Enterprise Edition in a server cluster, regardless of the physical node that is running Exchange 2003.

  • Interaction between Exchange 2003 Enterprise Edition and the Cluster service   The Windows Cluster service monitors the physical nodes in a cluster and the resources hosted on the nodes. There is continuous interaction between the Cluster service and the various Exchange cluster resources that compose an Exchange Virtual Server in a cluster.

  • Cluster-Specific Configurations   While running Exchange 2003 in a Windows server cluster is very similar to running a standalone (that is, non-clustered) Exchange server, there are some considerations that are unique to clusters. For example, certain Exchange 2003 resources that run in a cluster require specific configurations to communicate in a cluster server.

For more information about Windows clustering technologies, see Clustering Technologies.