In simple failover, the most basic form of clustering, two servers make a cluster. If one fails, the other takes over. But if the surviving server comes up short in processing power, memory or storage resources, it too can fail or slow users down. Microsoft Corp. certifies clustering hardware and configurations for Cluster Server. Compaq Computer Corp. is certifying as many of its recent ProLiant servers as possible.
Hardware certification is crucial.
Microsoft will not support its Cluster Server on unapproved hardware or configurations. Although clustering can be done in many ways, simple failover will gain the broadest use, because Microsoft Cluster Server will be so widely available in NT 5.0. In a failover setup, the two clustered servers connect to each other via dedicated network interface cards. The NICs exchange is called a heartbeat signal. If an application, resource or server fails, the heartbeat stops, and an alert goes out for the other server to take over.