Failover Cluster

Applies To: Windows Server 2008

A failover cluster is a group of independent computers that work together to increase the availability of applications and services. If one of the clustered servers fails, another server begins to provide service (a process known as failover).


The following is a list of all aspects that are part of this managed entity:

Name Description

Active Directory Permissions for Cluster Accounts

When you create a new clustered service or application, a computer object (computer account) for that clustered service or application must be created in the Active Directory domain. This computer object is created by the computer object of the cluster itself. If the computer object of the cluster itself does not have the appropriate permissions, it cannot create or update the computer object for the clustered service or application.

Failover Cluster Configuration Availability

The cluster configuration database contains essential information for the function of a failover cluster. A copy of the cluster configuration database is maintained on each node. If the quorum configuration for the cluster includes a witness disk, a copy of the cluster configuration database is also maintained on the witness disk. The Cluster service replicates the latest version of the cluster configuration database to all locations where it is stored.

Quorum and Connectivity Needed for Quorum

A failover cluster can run only when a majority of cluster elements (a quorum) are running and in communication. These elements usually include the nodes and, with some quorum configurations, a witness disk (which contains a copy of the cluster configuration) or witness file share. When enough of these elements are running and in communication, the cluster has achieved quorum and can run.

Registry Checkpointing

Some clustered services and applications store information outside of the cluster configuration database, in registry keys that the Cluster service monitors and replicates between nodes. If the Cluster service is prevented from writing to such a registry key, the corresponding cluster resource might not function correctly.

Verbose Cluster Logging

You can turn on verbose cluster logging to provide additional detail in logs for troubleshooting. However, a failover cluster can function regardless of whether verbose cluster logging is turned on.

Failover Clustering