Updated: October 4, 2007
Applies To: Windows Server 2008, Windows Server 2008 R2
Each node in a cluster provides a particular set of resources to the group. Windows Media Services might be only one of several resources available on a particular node, and not all of the nodes on a given cluster might have Windows Media Services installed. If a node fails or is shut down, the clustering software reallocates the server demand to the other members of the cluster that have the correct resources available. This process is called failover. There are two common failover modes:
Cascading failover. Resources from the failed node are distributed evenly to other nodes throughout the cluster. This mode assumes that all of the other nodes in the cluster have some additional capacity.
N+1 failover. Resources from the failed node are redirected to a standby node that is held in reserve. This mode assumes that most or all of the cluster's excess capacity is assigned to one node.
When a failed or offline node is recovered, the clustering software can automatically move some or all of the redistributed resources back to their original location.
In addition to controlling failover, clustering software allows administrators to control and manage the nodes as a single system rather than as individual computers.
To provide effective failover protection, each node in the cluster must have a direct connection to the content source. The content source can be an encoder, a publishing point, or a file server.
Each cluster can support up to 32 computers under a single, logical Internet name. The cluster automatically detects server failure or change of status and redirects requests to the remaining servers while maintaining a seamless operational appearance to the user.