To Change a window 2022 Datacenter VNN cluster into DNN cluster without downtime

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To Change a window 2022 Datacenter VNN cluster into DNN cluster without downtime

Arjun R B 20

My Environment is a business-critical High Availability and Disaster Recovery with 4 nodes and 1 cloud witness environment. with 2 nodes in primary and 2 nodes in DR with cloud witness in DR region. This environment has Mutiple instance and SQL Availability groups and Listeners through which applications are connected. The Failover Cluster is configured in Virtual network name (VNN). Now we want to change the cluster to (DNN) Distributed Network Name. Is it possible to change all the AG roles and cluster into DNN without any downtime or impact.

Debarchan Sarkar - MSFT 1,131 Reputation points Microsoft Employee

2024-02-25T01:27:04.9666667+00:00

Distributed Network Name (DNN) is a feature of Windows Server 2016 and later, which improves the availability of client connections and enables seamless failovers across different subnets. However, switching from a Virtual Network Name (VNN) to a DNN isn't a straight forward process as there's no built-in mechanism to convert a VNN based failover cluster to a DNN based one without some downtime. Transitioning from VNN to DNN typically involves creating a new SQL Server Always On Availability Group with DNN and migrating your databases to that new group. This will likely cause a brief interruption in your service during the switchover. Here's a simplified overview of the steps: Set up a new SQL Server Always On Availability Group with DNN: In the Failover Cluster Manager, create a new role for the Distributed Network Name and then set up a new SQL Server Always On Availability Group using this DNN. Prepare your databases for migration: Depending on the size of your databases and the performance of your environment, it might be beneficial to perform a full backup of databases and restore them to the new AG group. If you have large databases or need to minimize data transfer time, you could use log shipping or other high-availability technologies to prepare for the migration. Perform the switchover: At an appropriate maintenance window, you would switch your applications to use the new AG group. This may involve updating connection strings or DNS entries, depending on how your applications connect to SQL Server. Validate the new configuration: After the switchover, validate that all functions are working correctly. Monitor the new AG group closely for any unexpected behavior.

Remember that these are high-level steps and the actual process may be more complex, especially in a large or high-availability environment. We recommend working with a DBA or consultant experienced with SQL Server Always On Availability Groups and Windows Failover Clustering for this process. As next steps: Start planning for creating a new SQL Server Always On Availability Group with DNN. Identify a suitable maintenance window for performing the switchover. Begin preparing your databases and applications for the migration.

Please let me know if you need further assistance.

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