To provide High Availability feature within your database environment you could take advantage of Database Mirroring when using SQL Server 2005. As with all critical databases, minimizing data loss and downtime are of the highest importance. Having "AlwaysOn" configuration within the SQL Server 2005 that allows a database to be highly available by automatically failing over to a “mirror” image of the database in the event of a disaster to the “principal” server. This feature is called Database Mirroring...(
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Read the complete post at http://sqlserver-qa.net/blogs/bc/archive/2007/12/10/2887.aspx