Or do you have to upgrade every FCI on the Failover Cluster? The documentation doesn't seem to be clear.
We have a 7 instances on a 3 node cluster. We want to upgrade only one of the instances from SQL Server 2008 to SQL Server 2012. Can we perform an upgrade or do we need to backup the instance as best we can, uninstall that instance, install SQL Server 2012 then add that instance back?
I know you can run SQL Server 2008 and SQL Server 2012 on the same failover cluster...
The installation makes it seem like you can upgrade a single instance, but I'm still apprehensive since we haven't tested and no documentation seems to explicitly state it's possible.