Introduction to Windows 2003 Clustering - Network Load Balancing (NLB) and Server Clusters
A cluster is a group of computers and storage devices that work together yet can be accessed as a single system. Clustering provides high availability for critical services and applications by maintaining two or more joined servers (or nodes); if one node or subcomponent fails, the other immediately assumes the functional responsibility.
Windows Server 2003 Network Operating System includes two different types of clustering technologies:
Network Load Balancing (NLB) Clusters
These types of clusters allow for the high availability of services that rely on the TCP/IP protocol. If a Network Load Balancing (NLB) server is down, the cluster is automatically reconfigured and the client connections are redistributed across the remaining servers. When a new node is added to the Network Load Balancing (NLB) cluster it is automatically recognized and the load is reconfigured and distributed.
The nodes of an Network Load Balancing (NLB) cluster are called members, and the only thing they share is a network connection and one or more virtual IP addresses.
Windows 2003 Network Load Balancing (NLB) clusters support maximum of 32 nodes.
True Server Clusters
True Server clusters are advanced technology clusters, consist of nodes that can share workloads and processes between different members of the cluster. In True Server cluster, the failed members can be automatically detected and the work which was performed by the failed member can be moved to another available functional member of the cluster. Following table shows the number of nodes supported in Windows 2003 Server cluster.
Windows 2003 OS |
Number of Nodes supported |
Storage Type |
Windows Server 2003, Enterprise Edition Windows Server 2003, Datacenter Edition
|
1-8 |
Fibre Channel |
Windows Server 2003, Enterprise Edition Windows Server 2003, Enterprise x64 Edition Windows Server 2003, Datacenter Edition Windows Server 2003, Datacenter x64 Edition
|
1-2 |
SCSI |