Let me first tell you my current environment in which there is one windows cluster on which there is sql cluster with two nodes, i.e, A and B in it. Of which, one A is active and B is passive. So, what I want is to use my passive node, i.e, B for some other application's database and make it work like active node for this application and A which will act as passive in this case. Using this I can utilize my one server which is free at a time.

The point is that can we do that?


Yes you can do that with Failover Clustering. But you will need to license this second instance.

If one node fails and can't be brought up quickly, you need to consider whether or not the hardware can support both instances for a period of time. In a 2-instance scenario, it is generally advised to have 3 nodes: active/active/passive.

  • Thanks for the quick response. I have enough hardware to support both instances at a time. Due to cost issue can't use the third server. That's why only using 2-instance scenario with 2 nodes: active/active – palmon Aug 23 '16 at 5:12

You can but Instance B will not be passive any longer which may require additional licensing costs to operate two active instances.


I think what you're wanting is to instance stack. You have one instance on Server A, let's call it Instance 1. Instance 1 primarily lives on Server A, but can fail over to Server B. Now you want to add another instance, Instance 2 on Server B. This is risky for one reason, what happens if Instance 1 and Instance 2 end up on the same server? Will each server have enough memory for both Instances to be running on it at the same time? In this setup, there's a lot of risks for competing resources. It can be done though, and I've seen much worse instance stacking.

For licensing, the second node is no longer free and will require licensing once it has an instance living on it.

  • Thanks for the quick response. And for thing you asked that if they end up on same server then my answer is yes. It is having enough memory to run at same time. And, I have license also for the same so I will try to implement it. Also, if you have more suggestions or prerequisites to perform this then do let me know. That would be of great help :) – palmon Aug 23 '16 at 5:09

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