Microsoft® SQL Server® 2008 For Dummies®

Chapter 19. Staying Alive: High Availability in SQL Server 2008

Many organizations depend upon their databases for the very livelihood of their businesses. For example, an e-commerce store would cease to operate without the database that drives its product catalog and ordering process. Similarly, a bank would be unable to process any customer transactions without access to live financial data.

In enterprises like these, time is literally money. You can directly measure the financial cost of database downtime in terms of lost revenue. There are also additional intangible factors, such as reputation and customer goodwill, that play a definite role. Would you want to do your banking with a financial institution that has unreliable databases?

For these reasons, SQL Server provides a number of high-availability solutions designed to reduce the amount of downtime suffered by your organization. Database mirroring allows you to maintain a completely redundant database environment that serves as a hot or warm standby in the event of a primary server failure. Log shipping lets you transfer the transaction log from a primary database to secondary database(s) on a regular basis, providing a way to both keep a backup server ready and waiting and to provide users with a secondary data source for queries where time is not of the essence.

Creating Redundancy with Database Mirroring

When you establish a database mirroring relationship, you define a partnership between two servers. The result of this ...