Beginning SQL Server™ 2005 Administration

Chapter 11. SQL Server High Availability

Picture this. You're sitting at your desk, reading your favorite tech blog, when all of a sudden, the phone rings. It's the help desk. "The server's down," the help desk technician informs you. It's the finance database server—your server.

The problem could be any number of things. A failed disk, network problems, or power outages are among the many things that can plague you as a database administrator. However, with the right combination of hardware and software, many of these outages can be avoided.

This chapter should provide you with a basic understanding of the topic of high availability, and the tools provided to help improve the availability of your databases. This chapter covers the following topics:

• Availability

• Clustering

• Log shipping

• Database mirroring

Unless otherwise stated, the high-availability topics covered in this chapter are available only in the Standard, Enterprise, and Developer Editions of SQL Server 2005.

Introduction to Availability

The definition of high availability is subjective. This is because you may have some applications that need to be available 24 hours a day, seven days a week; and you may have other database applications that only need to be available during business hours. High availability isn't always about full-time operations, but rather about services being accessible to your users when they need them.

High availability is also about being able to meet Service Level Agreements (SLAs), which define your requirements ...