As part of trouble shooting a performance issue with a SQL Server cluster I found out that the nodes haven't been patched properly to the same level. It is a 2 node active / passive cluster. SQL Server performance was much better on node with higher patch level.

The nodes have been patched to the same level now.

Just trying to understand how SQL Server and the would have behaved in this sort of a scenario? Would this patch level miss match have caused other issue with the cluster?


SQL Server versions on nodes were different and SQL Server needed to do upgrade or downgrade after failover. This increased failover time.


Well that can be possible depending upon which patch you applied. If you refer to Microsoft documentation for the versions, you will see the description of what's different between those 2 patch builds . For example 2014 SP3 have some performance gains compared to SP2. Again it might be possible because of different patch but performance gain include various other factors as well. If you share more details like what improvements you see might help further.

To check whats new in patch that has been introduced please refer sqlserverbuilds

Also, as a good practice you should have both the nodes on same patch versions.

Moreover There is 2014SP3 latest , so you can test that SP in lower env and decide to push in prod once all looks GREEN across both the nodes

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