As part of Microsoft Windows 2000 Advanced Server and Windows NT 4.0 Enterprise Edition, MSCS clustering technology is used to increase the availability of business-critical applications and resources on Microsoft Windows servers. MSCS integrates with the core components of Windows 2000 and Windows NT, and provides a mechanism to monitor hardware and software resources, detect failure of such resources, and initiate a recovery of the resources on another server. A clustered application has the ability to move from one cluster server to another via a failover. Each application group, sometimes called a virtual server, operates as an independent entity on the cluster. The virtual server can move independently among the clustered servers.
Clients connect to the virtual server, rather than directly to a clustered server.
This enables clients to automatically maintain connection to the application, regardless of which clustered server currently owns the application. Multiple applications can be installed on an MSCS cluster and the applications need not be aware that they are running on a cluster. This article discusses the cluster-aware version of Microsoft Exchange 5.5 Enterprise Edition, although the concepts apply to Microsoft Exchange 2000, Microsoft SQL Server, and other clustered applications. Managing Clusters Clusters operate differently than stand-alone servers. Most management applications were designed for stand-alone servers and manage them quite well.