Chapter 19

Database Mirroring


  • Overview
  • Architecture
  • Operation Modes
  • Setup, Configure, and Monitor
  • Troubleshooting
  • Database Availability Scenarios

Database mirroring is a reliable, high-availability solution in SQL Server 2012. Maximizing database availability is a top priority for most DBAs. It is hard to explain the pain a DBA goes through when a database goes down; you cannot get it right back online, and at the same time, you’re answering pointed questions from your manager. Database mirroring can come to the rescue in certain scenarios, which this chapter explains. It can help you get the database back online with automatic or manual failover to your mirror database, adding another high availability alternative to the SQL Server 2012 arsenal. This chapter explains database mirroring concepts, shows you how to administer the mirrored database, and provides an example demonstrating how to implement database mirroring. The database snapshot is also discussed, which you can use with database mirroring to read the mirrored databases.


Database mirroring is a high-availability solution at the database level, implemented on a per-database basis. To maximize database availability, you need to minimize planned as well as unplanned downtime. Planned downtime is common, such as changes you have to apply to your production system, hardware upgrades, software upgrades (security patches and service packs), database configuration changes, ...

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