Application Center & Microsoft's Clustering Technologies

Although many people use the term cluster to simply refer to a farm of identical servers, each running an instance of a Web or conventional server application, Microsoft uses the term to refer to several different technologies—Microsoft Cluster Service (MSCS), Network Load Balancing (NLB) service, Component Load Balancing (CLB) service, and application-specific clustering features—not all of which are supported by Application Center. Each technology delivers some subset of the four traditional clustering attributes:

• Scalability, the ability to increase performance by simply adding machines to a cluster
• Availability, the ability to reduce downtime by adding redundant machines to a cluster
• Generality, the ability to function with virtually any type of application
• Transparency, which enables developers, administrators, and users to treat a cluster as a single machine

MSCS offers high availability (across up to four machines) and transparency. It also supports a high level of generality, although applications must be rewritten to be “cluster aware.” It does not provide scalability. Application Center does not deliver any features for setting up or managing MSCS clusters and is not supported on such clusters.