Professional SQL Server® 2005 Performance Tuning

15.3. High Availability and Disaster Recovery

Along with sizing the database infrastructure, it is also important to incorporate high availability and disaster recovery into the overall architecture design. A high availability SQL Server solution will mask the effects of a hardware or software failure while ensuring that applications remain available and minimizing downtime. However, before you select a high-availability solution, it is important to understand the goals of this solution. SQL Server 2005 comes with several features that increase the availability of production databases, but these features are different in terms of what they can achieve and typically require additional infrastructure that will add to your cost of implementation. Before you start to design your highly available SQL Server solution, you should answer some of the following questions to get a sense of what features that you should deploy:

• Is failover going to be automatic or manual?

• Is a failure going to be detected automatically and appropriate action taken?

• Is Transparent Client Redirect important?

• How much downtime can you afford?

• What is the typical size of your transaction logs?

• Where are the failover servers located? In the same datacenter, a different datacenter in the same building, a different building, and so on.

After you have answered some of these questions, it is much easier to pick the correct feature that will help you achieve your high-availability goals.

Best Practice Don't deploy high-availability ...