Provide High Availability for Multiple Services and Applications

Applies To: Windows Server 2008

In this scenario, the goal is to provide high availability for multiple services and applications. Part of this goal is to make the most of an investment in server hardware—placing multiple services and applications on the cluster—while avoiding overloading that would lead to a reduction in server performance.

However, when evaluating this scenario, it is important to weigh the relative value of each of the applications in supporting your organization’s goals. If one of your applications is less important that the others, you might not provide the maximum server capabilities and staff for that application, and instead allow it to occasionally stop if there are problems. In contrast, you might give the highest priority to applications that are most important to your organization, that is, place those applications (and only those) in a cluster. This would allow you to give the maximal amount of server resources to those applications, increasing their performance and uptime.

If a user on a client computer attempts to perform an action with one of the clustered services or applications, and the action is interrupted, the service or application on the client computer must automatically retry the action. 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 five client-server applications. Of those five, A. Datum Corporation wants to provide 99.99% availability (down for less than 1 hour per year) for only four. For the fifth application, a much lower level of availability is adequate, and it would never be preferable for that application to be available if it meant that one of the other four was not available. A. Datum will create a design that provides high availability for the four important applications, and lower availability for the fifth application.

For additional deployment goals, such as the goal of providing high availability for servers running Hyper-V (so you can cluster applications that run on a variety of different operating systems), see Identifying Your Failover Cluster Deployment Goals.

Additional references

Appendix B: Identifying Availability Requirements for a Failover Cluster