When it comes to applying patches or upgrades to a SQL Server instance in a cluster, there are certain considerations that need to be taken into account. One of these considerations is the “Cluster Resource DLL Update Restart Check” warning that may appear during the patching process.
Upon encountering this warning, it is important to understand its implications and how it can potentially impact other SQL Server instances running on the same node.
The warning message, as seen in the setup logs, states that the local computer is an owner of a cluster group that contains the SQL Server service, Analysis Services service, or a generic service for a failover cluster instance. If the patching process continues, it may result in the SQL Server instances being taken offline, causing downtime.
This warning is often overlooked or misunderstood, leading to unexpected downtime for other SQL Server instances running on the same node. It is crucial to carefully evaluate the warning and consider the potential impact on other instances before proceeding with the patching process.
Based on the experience of one of my clients, who faced downtime for 10 other instances due to this issue, it is evident that this warning should not be taken lightly. Even if previous patches did not cause any issues, it does not guarantee that future updates will have the same outcome.
My advice is to always pay attention to the upgrade rules and warnings provided during the patching process. In the case of the “Cluster Resource DLL Update Restart Check” warning, it is essential to understand that any other SQL Server instances active on the same node might be restarted due to the cluster resource DLL update.
If you have not planned for these other instances to be restarted, it is crucial to factor this into your upgrade plans. By being aware of this potential impact, you can take necessary precautions and minimize any potential downtime or disruptions to your SQL Server environment.
Remember, thorough planning and understanding of the upgrade process are key to ensuring a smooth and successful patching experience for your SQL Server instances in a cluster.