Model 3: Majority node set server cluster configuration

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

Model 3: Majority node set server cluster configuration

Model 3 shows how you can configure multiple nodes in a majority node set server cluster.

In this cluster model, each node maintains its own copy of the cluster configuration data. The Majority Node Set resource, acting as the Quorum Resource, ensures that the cluster configuration data is kept consistent across the different nodes. The quorum traffic travels unencrypted over Server Message Block (SMB) file shares. The main advantage of this model is that cluster nodes do not have to be physically connected to one or more cluster disks.

Important

• Use a majority node set cluster only in targeted scenarios. Do not configure your cluster as a majority node set cluster unless it is part of a cluster solution offered by your Original Equipment Manufacturer (OEM), Independent Software Vendor (ISV), or Independent Hardware Vendor (IHV). The single quorum device server cluster, the standard cluster model available in Windows NT and Windows 2000, will still cover the vast majority of your cluster deployment needs.

For detailed instructions on creating a majority node set cluster, see Create a cluster.

The following figure represents an example of a majority node set server cluster.

For example, in an 8-node cluster, you could use this model to physically locate 5 nodes of the server cluster in one data center (for example, in Seattle) and the other 3 nodes in another data center some distance away (for example, in Los Angeles) while still presenting a single point of access to clients.

Other advantages of this model include the following:

• If an application inadvertently corrupts one of the local quorum disks or if you need to take a quorum disk offline for maintenance, the cluster still remains available.

• You can create clusters without cluster disks. This configuration is useful if you need to host applications that can failover, but where there is some other, application-specific way, to replicate or mirror data between nodes.

Number of nodes in a majority node set cluster

The main disadvantage of this model is that, for n-node clusters, if more than half the nodes fail at any one time, then the cluster itself fails. The cluster is then said to have lost quorum. This is in contrast to the n-node single quorum device server cluster model which will not fail even if only a single node remains in the cluster. The table below shows the maximum number of node failures allowed in a majority node set cluster before the cluster fails.

Note

• If the server cluster loses quorum, you can restore it by forcing the quorum. For more information, see Force quorum in a majority node set server cluster.