Cluster technologies are becoming increasingly important to ensure service offerings meet the requirements of the enterprise. Windows 2000 and Windows Server 2003 support three cluster technologies to provide high availability, reliability and scalability. These technologies are: NLB, CLB and Server cluster. These technologies have a specific purpose and are designed to meet different requirements.
- Server cluster provides failover support for applications and services that require high availability, scalability and reliability, and is ideally suited for back-end applications and services, such as database servers. Server cluster can use various combinations of active and passive nodes to provide failover support for mission critical applications and services.
- NLB provides failover support for IP-based applications and services that require high scalability and availability, and is ideally suited for Web tier and front-end services. NLB clusters can use multiple adapters and different broadcast methods to assist in the load balancing of TCP, UDP and GRE traffic requests.
- Component Load Balancing provides dynamic load balancing of middle-tier application components that use COM+ and is ideally suited for application servers. CLB clusters use two clusters. The routing cluster can be configured as a routing list on the front-end Web servers or as separate servers that run Server cluster.
NLB and server clusters compliment each other in complex architectures: NLB is used for load balancing requests between front-end web servers while server clusters provide high availability for backend database access.NLB and server clusters cannot be used on the same set of servers