Unlike SQL 2000, SQL 2005 setup on a cluster now requires you to provide domain groups for each clustered service – like SQL Database Engine, SQL Agent, FTS, Analysis Services.
Many customers have asked me interesting questions about domain groups and I wanted to take a moment to address them through this blog.
First, I would like everybody to read this KB article published by Microsoft which provides some of the best practice recommendations for using domain groups – KB 915846
The most important thing to understand about domain groups is that you CANNOT change them after installing SQL Server 2005 cluster.
If you want to change them, then you have to re-install SQL Server. Refer to the above KB on how to do this.
If you were to move your SQL Server 2005 cluster from one domain to another and decided to change the domain groups, you will have to re-install SQL Server. Refer to the above KB on how to do this.
Hope this helps!