Chapter 47. Database Mirroring


  • Database mirroring overview

  • Configuring database mirroring

  • Monitoring database mirroring

  • Pausing or removing database mirroring

  • Role switching

Achieving high database availability is one of the most important goals for critical business applications. Database mirroring is a software solution offered by Microsoft SQL Server 2008 to achieve high database availability. Database mirroring enables you to maintain a copy of your production database that could potentially be completely synchronized on a separate server for failover in the event of a failed production server or database. Like log shipping, database mirroring provides high availability at the database level; but unlike log shipping, database mirroring can be configured to provide no data loss and automatic failover.

Database Mirroring Overview

Database mirroring was officially supported with SQL Server 2005 SP1. It is available in Enterprise and Developer Editions, and with some restrictions in Standard Edition. Developer Edition can be used only for development purposes and not for production.

The basic concept of database mirroring is very simple. Database mirroring maintains a hot standby database (mirror database) that is kept in sync with the production database (principal database) by transferring transaction log records from the principal database to a mirror database over the network, either synchronously or asynchronously. In case of a failure, the mirror database can be quickly ...

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