Windows Server 2008: Failover clustering, network load balancing drive high availability

Service providers can help customers ensure high availability of their servers, applications and services using failover clustering and load balancing in Windows Server 2008. Most of your customers know business productivity and revenues can be drastically affected if a mission-critical server, application or service fails. Indeed, one of the main objectives for IT departments everywhere […]

Service providers can help customers ensure high availability of their servers, applications and services using failover clustering and load balancing in Windows Server 2008.

Most of your customers know business productivity and revenues can be drastically affected if a mission-critical server, application or service fails. Indeed, one of the main objectives for IT departments everywhere is providing high availability for mission-critical resources. Toward that goal, service providers can implement high-availability alternatives in Windows Server 2008 to mitigate server outages for their Windows shop customers.

The first step in designing a Windows-based high-availability solution entails understanding the two main high-availability alternatives available with Windows Server 2008; failover clustering and network load balancing. These options tackle high availability in different ways.

Failover clustering: At the macro level, a Windows Server 2008 failover cluster provides high availability by eliminating the threat of a single point of failure for a server, application or service. Normally, if a server with a particular application or service crashes, the application or service is unavailable until an administrator manually rectifies the problem. But if a clustered server crashes, another server within the cluster will automatically take over the failed server's application and service responsibilities without intervention from an administrator or impact on operations.

Windows Server 2008 supports the shared-nothing cluster model, in which two or more independent servers, or nodes, share resources; each server owns and is responsible for managing its local resources and provides nonsharing services. In case of a node failure, the disks, resources and services running on the failed node fail over to a surviving node in the cluster. For example, if an Exchange server is operating on node 1 of the cluster and it crashes, the Exchange application and services will automatically fail over to node 2 of the cluster. This model minimizes server outage and downtime. Only one node manages one particular set of disks, cluster resources and services at any given time.

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