Troubleshooting host name changes in SQL Server

 When the machine name is changed where we have installed SQL Server, all the instances services are started but replication, Jobs, Alerts, Maintenance plans causes errors. Hence we have to rename the instance.

To rename instance we can use the following SP

Steps:

1.      Check the old server name as follows

SELECT @@servername

2.      Drop the server and add the new server name

             SP_DROPSERVER   <oldName>

           SP_ADDSERVER <newName>, local

3.      Restart the instance

4.      Check the server name again

SELECT @@servername

Applying a SQL Service Pack or Hotfix in a 2-Node Active/Passive SQL Cluster Environment

Applying a SQL Service Pack or Hotfix in a 2-Node Active/Passive SQL Cluster Environment

When managing a SQL Server Cluster, applying service packs or hotfixes requires careful execution to avoid downtime and ensure high availability. Follow this step-by-step guide to apply a SQL Service Pack (SP) or hotfix in a 2-node Active/Passive SQL Cluster environment.

Cluster Configuration:

Active SQL Server: SQLDBANOWDBALABS

Passive SQL Server: SQLDBANOWDBALABS-DR

Step by Step update Process:-

1. Apply the SQL Service Pack on the Passive Server

Log in to SQLDBANOWDBALABS-DR (Passive Node).

Initiate the SQL Service Pack/Hotfix installation.

Follow the installation wizard, ensuring all necessary components are updated.

Once the installation is complete, restart the Passive Node if prompted.

2. Failover SQL Cluster to the Passive Server

Open Failover Cluster Manager.

Select the SQL Server Cluster Role (SQLDBANOWDBALABS instance).

Initiate a failover to move the active role to the Passive Node (SQLDBANOWDBALABS-DR).

Post Failover:

New Active Server: SQLDBANOWDBALABS-DR

New Passive Server: SQLDBANOWDBALABS

3. Apply the SQL Service Pack on the New Passive Server

Log in to SQLDBANOWDBALABS (Now Passive Node).

Initiate the SQL Service Pack/Hotfix installation.

Follow the installation wizard and complete the update process.

Restart the server if prompted.

4. Failback SQL Cluster to the Original Active Server

Open Failover Cluster Manager.

Select the SQL Server Cluster Role (SQLDBANOWDBALABS-DR instance).

Initiate a failover to move the active role back to SQLDBANOWDBALABS.

Post Failback:

Active Server: SQLDBANOWDBALABS

Passive Server: SQLDBANOWDBALABS-DR

5. Perform Post-Upgrade Health Checks

Verify SQL Cluster Services:

Ensure all cluster resources are online.

Check Failover Cluster Manager:

Validate Cluster Nodes’ status.

Ensure Cluster Disk Health is optimal.

Review SQL Server logs for any errors.

Test application connectivity and functionality.

How to apply patches in SQL Server Always On Environment

 SQL Always On Environment:

Apply a SQL Service Pack or hot-fix in SQL Server Always-On environment.

Primary SQL Replica: SQLDBANOWDBALABS

Secondary SQL Replica: SQLDBANOWDBALABS-DR

Apply SP/Hot-fix on all Secondary AG Replica's 

Finally Apply SP/Hot-fix on Primary AG Replica.

1. On Secondary AG Replica: (SQLDBANOWDBALABS-DR)

Ensure AG Databases are in Synchronized Status.

Apply the SQL Service Pack on Secondary Replica Server. (SQLDBANOWDBALABS-DR)

Post SP/hot-fix installation completion, restart the Secondary Replica Server if prompted.

2. On Primary AG Replica: (SQLDBANOWDBALABS)

Failover the SQL AG Group from Primary Replica to Secondary Replica.

3. Post AG Group Failover:

New Primary Replica : SQLDBANOWDBALABS-DR

New Secondary Replica: SQLDBANOWDBALABS

4. On New Secondary AG Replica: (SQLDBANOWDBALABS)

Apply the SQL Service pack on New Secondary Replica Server. (SQLDBANOWDBALABS)

Post SP/hot-fix installation completion, restart the New Secondary Replica Server if prompted.

5. On New Primary AG Replica: (SQLDBANOWDBALABS-DR)

Failback the SQL AG Group from Primary to Secondary Replica.

6. Post AG Group Failback:

Primary Replica : SQLDBANOWDBALABS

Secondary Replica: SQLDBANOWDBALABS-DR

7. Finally verify the SQL AG Group Health Check in AG DashBoard Reports.