Data Center High Availability Clusters Design Guide

Clusters define a collection of servers that operate as if they were a single machine. The primary purpose of high availability (HA) clusters is to provide uninterrupted access to data, even if a server loses network or storage connectivity, or fails completely, or if the application running on the server fails. HA clusters are mainly used for e-mail and database servers, and for file sharing. In their most basic implementation, HA clusters consist of two server machines (referred to as “nodes”) that “share” common storage. Data is saved to this storage, and if one node cannot provide access to it, the...