Scalability (Server Clusters: Frequently Asked Questions for Windows 2000 and Windows Server 2003)

Applies To: Windows Server 2003, Windows Server 2003 R2, Windows Server 2003 with SP1, Windows Server 2003 with SP2

Q. Do Server clusters enhance server scalability?

A. The primary goal of Server clusters is to provide a highly available platform for applications.

There are some types of applications which can be scaled-out to take advantage of a set of machines. More machines can be added to the set to increase the CPU or memory available to the application. Applications of this type are typically scaled by partitioning the data set. For example, a SQL Server database may be scaled out by partitioning the database into pieces and then using database views to give the client applications the illusion of a single database.

Server clusters do not provide facilities to partition or scale-out an application; however, Server clusters allow such applications to be scaled-out in a highly available environment. Each of the partitions can be failed over independently within the set of machines (or to additional spare nodes) so that in the event of failure, a partition of the application remains available.

Q. Do Server clusters provide load balancing of applications?

A. Server clusters provide a manual load balancing mechanism. Applications can be moved around the servers of a cluster to distribute the load.

There are no automated tools provided with the operating system to automatically load balance applications and no enhanced failover policies that use load to determine the best placement for an application.