Steps to Uninstall SQL Server Failover Clustered Instance
Due to various reasons DBAs may need to uninstall SQL Server instances. The reasons could be due to retiring the old server after migrating to a new server, the installation got corrupted due to various problems, after failure of installation, etc. Starting with SQL Server 008, the way to uninstall SQL Server clustered instance has changed, where the uninstallation has to be performed of each node of the cluster which SQL Server instance is part of. Sometimes there can be requirement to remove only one node in which case the uninstall has to be performed on only that particular node. Below are some of the important steps to be followed to uninstall SQL Server clustered instance.
Steps to Un-Install SQL Server Clustered Instance
Browse to the SQL Server installation media folder and from the root setup media folder, double-click setup.exe by choosing Run-as-Administrator. If the media if present on network share or DVD disk, then copy the media to local drive.
Launch the SQL Server Installation Wizard which will bring the SQL Server Installation Center. To remove a node to an existing failover cluster instance, click Maintenance in the left-hand pane, and then choose “Remove node from a SQL Server failover cluster”.
The System Configuration Checker will run a discovery operation on the server. click OK.
After that Setup Support Files gets installed and then the System Configuration Checker verifies the system state of the system before Setup can continue further. After the check is complete successfully with all green, click Next to continue.
On the Cluster Node Configuration page, use the drop-down box to choose the name of the SQL Server failover cluster instance to be modified during this Setup operation. The node to be removed is listed in the Name of this node field.
The Ready to Remove Node page displays a tree view of options that were specified during Setup. To continue, click Remove.
Monitor the remove operation for successful completion. In case of any errors, review the setup logs and take appropriate action and then start from the first step of the uninstall process again.
Once the remove node operation completes, verify from control panel and SQL Server Configuration Manager to make sure the instance has been removed.
Reboot the node
Perform the same operations on other nodes from where the SQL Server instance has to be uninstalled or removed.
Delete any folders or files related to previous SQL Server instance, if not required any more.
Reinstall the failover instance if required and apply Service Pack/Cumulative Update if applicable.
SQL Server 2005 or before, uninstall has to be initiated from the control panel on active node and go through the uninstall wizard and choose the node which was to be removed. Other shared components are to be removed on both the nodes from control panel.
This is applicable on below versions of SQL Server
SQL Server 2005
SQL Server 2008 R2
SQL Server 2012
SQL Server 2014
Hope this was helpful.
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