I know running multiple instances, and different versions of SQL is fully supported by MS. With that said I ran across an article on this site by Brad Mcgee that stated "Running multiple instances of SQL Server on the same node is not recommended." http://www.sql-server-performance.com/articles/clustering/clustering_best_practices_p1.aspx This is the only place I've seen anything like this recommendation. The reason why I'm pursuing this is because we are planning on building an SQL cluster to consolidate DBs for several different applications we house. In order to stay in support for our apps we will be running SQL 2005 SP3 and SQL 2008 SP1 with at least two clustered instances for each version on our three node cluster. My intention is to run all nodes Active. Obviously we will leave a performance buffer to sustain a node failure. Does anyone know why running multiple instances is not recommended? I'm aware of resource concerns when running multiple SQL instances and I'm taking that into account for our setup. Thank you!