Failover Clustering (II)

The failover mechanism

In the cluster, shared resources can be seen from all computers, or nodes. Each node automatically senses if another node in the cluster has failed, and processes running on the failed node continue to run on an operational one. To the user, this failover is usually transparent. Depicted in the next figure is a two-node cluster; both nodes have local disks and shared resources available to both computers. The heartbeat connection allows the two computers to communicate and detects when one fails; if Node 1 fails, the clustering software will seamlessly transfer all services to Node 2.
 

 
The Windows service associated with the failover cluster named Cluster Service has a few components:

• Event processor;
• Database manager;
• Node manager;
• Global update manager
• Communication manager;
• Resource (or failover) manager.

The resource manager communicates directly with a resource monitor that talks to a specific application DLL that makes an application cluster-aware. The communication manager talks directly to the Windows Winsock layer (a component of the Windows networking layer).
The failover process is as follows:
Read more »