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


A server cluster node is a system that has a working installation of Windows Server 2003, Enterprise Edition or Windows Server 2003, Datacenter Edition and the Cluster service. By definition, a node is always a member of a server cluster. For more information on the Cluster service, see Cluster service.

Nodes have the following characteristics:

  • Every node is attached to one or more cluster storage devices. Each cluster storage device attaches one or more disks. The disks store all of the cluster's configuration and resource data. Each disk can be owned by only one node at any point in time, but ownership can be transferred between nodes. The result is that each node has access to all cluster configuration data.

  • Every node communicates with the other nodes in the cluster through one or more physically independent networks, known as interconnects. Network adapters, also called network interfaces, attach nodes to networks.

  • Every node in the cluster can detect another system joining or leaving the cluster.

  • Every node in the cluster can detect the resources that are running locally and the resources that are running on the other cluster nodes.

  • All nodes in the cluster are grouped under a common name, the cluster name, which is used when accessing and managing the cluster.

The following states describe a node's participation in server cluster operation:

State Meaning


The node is not actively participating in cluster operations.


The node is in the process of becoming an active participant in the cluster operations.


The node is actively participating in cluster operations but cannot take ownership of resource groups and cannot bring resources online.


The node is actively participating in all cluster operations.


The state cannot be determined.

An active node can host cluster groups. For more information about groups, see Server Cluster groups.

When running Cluster Administrator for the first time on a server node, the administrator can choose whether that node forms its own cluster or joins an existing cluster. When a node is powered up, the Cluster service already installed on that node searches for other active nodes on networks enabled for internal cluster communications.

Forming a new cluster

If a cluster does not already exist, the node attempts to form its own cluster by gaining control of the quorum resource. If the node gains control of the quorum resource, the node forms its own cluster and uses the recovery logs in the quorum resource to update its cluster database. The Cluster service maintains a consistent, updated copy of the cluster database on all active nodes

For more information about the quorum resource, see Quorum resource. For more information on the cluster database, see Cluster database.

Joining an existing cluster

A node can join an existing cluster if it can communicate with another cluster node. If a cluster exists and the joining node finds an active node, it attempts to join that node's cluster. If it succeeds, the Cluster service then validates the node's name and verifies version compatibility. If the validation process succeeds, the node joins the cluster. The node updates its copy of the cluster database from that on the other active nodes.