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.
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.