Chapter 52. Providing High Availability
In This Chapter
Configuring a warm standby server with Enterprise Manager or SQL Server Agent
Understanding failover clusters and availability
The availability of a database refers to the overall reliability of the system. The Information Architecture Principle, discussed in Chapter 1, lays the foundation for availability in the phrase "readily available." Defining readily available varies by the organization and the data. A database that's highly available is one that rarely goes down. For some databases, being down for an hour is not a problem; for others, 30 seconds of downtime is a catastrophe. Organization requirements, budget constraints, and other resources will dictate the proper solution.
A plan for maintaining availability is executed at three distinct cascading levels:
Maintaining the primary database's availability
Providing a near-instant substitute, or secondary, database
Recovering from a lost database
Several methods of increasing availability are unrelated to SQL Server proper. The quality and redundancy of the hardware, the quality of the electrical power, preventive maintenance of the machines and replacement of the hard drives, the security of the server room—all of these contribute to the availability of the primary database. The first line of availability defense is quality hardware.
If a database is lost because of hardware failure, the third level of availability is executed and the database must be recovered according to the ...
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