Database mirroring is a primarily software solution for increasing database availability. Mirroring is implemented on a per-database basis and works only with databases that use the full recovery model. The simple and bulk-logged recovery models do not support database mirroring. Database mirroring is supported in SQL Server Standard and Enterprise.
Database mirroring offers substantial availability and provides an easy-to-manage alternative or supplement to failover clustering or log shipping. When a database mirroring session is synchronized, database mirroring provides a hot standby server that supports rapid failover with no loss of data from committed transactions. During a typical mirroring session, after a production server fails, client applications can recover quickly by reconnecting to the standby server.
You cannot mirror the master, msdb, temp, or model databases.
- Database Mirroring Overview
Introduces the components of database mirroring.
- Database Mirroring Sessions
Describes how database mirroring sessions operate: concurrent sessions, the threads created for each session, and the prerequisites for a session, and so on.
- Database Mirroring Operating Modes
Contains information about the synchronous and asynchronous operating modes for database mirroring sessions, and about switching partner roles during a database mirroring session.
- Role Switching During a Database Mirroring Session
Contains information about switching partner roles during a database mirroring session, including automatic failover, manual failover, and forced service (with possible data loss). Also, contains information about estimating the interruption of service during role switching.
- Automatic Page Repair During a Database Mirroring Session
Describes how a database mirroring partner running on SQL Server 2008 or later versions responds to errors that prevent reading a data page.
- Mirroring States
Describes the possible mirroring states of a mirrored database.
- Database Mirroring Deployment
Contains information about setting up database mirroring and connecting clients to a mirrored database.
- Database Mirroring Administration
Contains information about how pausing, resuming, and stopping a database mirroring session, and monitoring your database mirroring sessions.
- Monitoring Database Mirroring
Contains information about using Database Mirroring Monitor or the dbmmonitor stored procedures to monitor database mirroring or sessions.