Upgrade Microsoft SQL Server Instances on Rehost
How to upgrade an instance of Microsoft SQL Server by rehosting the instance to a node that has a newer version of Microsoft SQL Server.
For this example there is a 3 node DxEnterprise cluster (Node1-W2K8R2, Node2-W2K12, Node3-W2K12R2) where a Microsoft SQL Server 2008 R2 instance by the name of INST4 is already installed on Node1-W2K8R2 and Node2-W2K12. The goal is to upgrade INST4 to Microsoft SQL Server 2014 on all 3 nodes, with the only downtime being the time it takes to rehost the instance to another server (less than 1 minute).
This example shows an upgrade to Microsoft SQL Server 2014, but the steps are the same when upgrading to Microsoft SQL Server 2012, 2016 or 2019.
Here are the steps:
Install a Microsoft SQL Server 2014 instance onto Node3-W2K12R2 with the name of INST4.
Verify the SQL Server service accounts across all nodes for INST4:
You will notice that the service accounts are different on the newly installed INST4. Using Microsoft SQL Server Configuration Manager you will need to modify the service accounts to match those of the existing (virtualized) INST4. For this example we will be using Built-in Microsoft System and Service accounts.
Run DxAdmin and connect to a node in the cluster.
Add Node3-W2K12R2 to the Vhost for INST4. In this example the Vhost name is VSQL4.
Rehost INST4 from Node1-W2K8R2 to Node3-W2K12R2.
VSQL4\INST4 is now upgraded to Microsoft SQL Server 2014.caution
Once upgraded, the instance will not be able to rehost to a lesser version of Microsoft SQL Server. You will need to complete the upgrade on the remaining nodes before the instance will be highly available again.
Remove Node1-W2K8R2 and Node2-W2K12 from the VSQL4 Vhost.
Upgrade INST4 from Microsoft SQL Server 2008 R2 to Microsoft SQL Server 2014 on both nodes.
Verify that the service accounts are the same as INST4 that is currently virtualized on Node3-W2K12R2. If they are not the same, use Microsoft SQL Server Configuration Manager to change the service accounts to match INST4 on Node3-W2K12R2.
Add the Node1-W2K8R2 and Node2-W2K12 nodes back to the VSQL4 Vhost.
Test rehost (if desired).
You have just upgraded INST4 from Microsoft SQL Server 2008 R2 to Microsoft SQL Server 2014 with almost zero down time!