I'm trying to transition from a Windows Failover Cluster running SQL 2012 in a clustered installation as a role between two physical nodes, 1x active and 1x passive/standby, to a SQL 2012 AlwaysOn Availability Group, such that I could add a third read-only node, as well as have true high availability.
As it currently stands, while failover is fast (less than 60 seconds) between node01 and node02 when migrating the SQL Server role, it's still a piece of the environment that is not truly highly available, such that maintenance or restarts could be performed on nodes at any point, without any interruption.
I've been unable to find any real guides for how to do this, only guides for how to setup a NEW SQL AlwaysOn availability group.
My desire though is to keep the current SQL instance name, and have a transition to AlwaysOn with the smallest amount of downtime possible (would be even better if it would be possible to do it without any downtime, but I'm realistic that it probably will require downtime).
How would I best go about doing something like this?