We are currently running sql server 2005 in a clustered environment. We have three nodes with only one node active at any given time. I'm trying to come up with an implementation plan, and more specifically a fallback plan in case we have trouble deploying sql server 2008R2. My plan for deployment is to deploy sql server 2008R2 on one node leaving the other to nodes in sql server 2005 in case we have an issue which would allow use to failover to one of the two nodes that is still runnin sql server 2005. Unfortunately we don't have a test environment that mirrors our production clustered environment, so we can't really test this completely before deploying. The other ugly part is that our test server doesn't even mirror one of our production servers so when testing we have to determine if we run into a performance issue if its relating to the server itsself or sql server 2008 needing to be tweated.
Any help or experience in this area would be greatly appreciated.