I know it sounds easy to upgrade a SQL Server Cluster environment from 2000 to 2005 version, as easy it mentioned within the Books Online for SQL Server 2005. When I have performed for the first time, my first thought was (do we need that or take out the reasons). But one thing is sure that SQL Server 2005 offers a number of enhancements you want to take advantage of, so if and when you've got to do it, you can proceed without a lot of downtime! Do not forget to evaluate the costs involved in this...(
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Read the complete post at http://sqlserver-qa.net/blogs/tools/archive/2007/11/16/upgrading-cluster-sql-server-choices-and-options.aspx