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How can I transition from a Windows Server 2012, 2-physical node Windows Failover Cluster, running SQL 2012 in cluster mode, to an AlwaysOn SQL 2012 Availability Group?

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?

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Ntiva
Asked:
Ntiva
2 Solutions
 
Vitor MontalvãoMSSQL Senior EngineerCommented:
I never did that but from what I read you are going to have a lot of work to do.
Check the SQL AlwaysOn Team Blog
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NtivaAuthor Commented:
Thanks Vitor for the link,

I've actually seen that blog series before, and while it appears to be fairly similar to what I'm trying to accomplish here, it is slightly different, as they begin with two Windows Failover Cluster's with database mirroring already in place, whereas I'm coming from a single 2-node FC without any mirroring.

While I could most likely adapt that to suit my needs, I'm still hoping that there is something else out there that exists, or someone who has done something similar to what I'm attempting to do now.
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Ryan McCauleyCommented:
Maybe I can clear something up - you are setting up a new Availability Group, but you can do it using an existing database (or set of databases). In this case, you can just use a new server, set up SQL Server on it, and then use that instance as your "mirror" or "secondary" instance of SQL, where you FCI is your primary database instance. Since an FCI can participate in an AG as one of the members, I think that would work. I'm not sure if you can use the same two nodes that are currently participating in your FCI, but assuming you want to and that's possible, here's what you'd do (assuming you have Node A and Node B):

1. Install a new stand-alone instance of MSSQL on Node A
2. Set up copy of database and configure users on new instance
3. Set up AlwaysOn AG, using FCI as primary and new instance as secondary
4. Ensure database is up to date and replicating properly
5. Repeat steps 1 and 2 on Node B
6. Add new instance on node B to existing AG from step 3
7. Confirm all instances are working in AG
8. Remove your FCI from the AG, making one of the other instances primary
9. If desired, install MSSQL on Node C and add it to the AG

There's no reason you couldn't seamlessly migrate to new instances using those steps. If for some reason you can't set up an AG on an existing cluster, you could extend the database onto Node C, destroy the cluster, and then set up two new instances of MSSQL and create an AG that includes all three of those servers.
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