Provide High Availability and a Disaster Recovery Option for a Service or Application

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Applies To: Windows Server 2008

In this scenario, the goal is to provide high availability and a disaster recovery option for a file, print, or application server (such as a server running a mail application, database application, or other client-server application). Providing a disaster recovery option involves investing in redundant hardware at a secondary site, plus replication technology to keep the data in relatively close synchrony between the two sites. The result is a multi-site cluster. Most of the time, the users are served by cluster nodes (servers) at the main site, but if necessary, they can be served by cluster nodes at the secondary site.

If the actions that users perform in this scenario are interrupted, the client computer must automatically retry those actions. This is necessary because a user action might sometimes be performed during a failover, meaning that the action would be interrupted (briefly) while failover occurred and would require an automatic retry to complete without further user action.

For more information, see the following topics:

For example, A. Datum Corporation may want to provide employees at their downtown location with a file server that achieves 99.99% availability (down for less than 1 hour per year), and also provide a disaster recovery option that maintains redundant hardware and replicated data at a branch location several hundred miles away. In ordinary failure situations, the cluster nodes (servers) at the downtown location provide high availability for files used by employees. If a disaster occurred that affected all servers in the downtown location, the files would instead be made available through servers at the branch location.

For additional deployment goals, such as the goal of providing high availability without a disaster recovery option, see Identifying Your Failover Cluster Deployment Goals.

Additional references

Appendix B: Identifying Availability Requirements for a Failover Cluster