Hi @Vishal ,
Based on your description, the topology you are using is an active/active cluster. And I agree with Jeffrey.
Advantages: The hardware resources of both nodes can be fully utilized (two or more SQLSERVER cluster instances need to be installed), and cost savings.
Disadvantages: Once a node fails over, there will be two instances of SQLSERVER running on another node at the same time. At this time, the two instances may contend for resources such as CPU, memory, I/O, etc. on this node, causing the performance of both instances to be affected. Sometimes users on both sides may not accept it. Therefore, the problem on the abnormal node must be resolved as soon as possible, and the failover instance must be switched back as soon as possible.
In addition to "active/inactive" clusters and active/active clusters, I will introduce another topology for you, that is, a cluster of N active + 1 inactive nodes. Take a 3-node cluster as an example. Install two SQLSERVER cluster instances on it. The Possible Owner of each instance contains two nodes in the cluster, but only one node is shared by both instances. Under normal conditions, the two SQLSERVERs are running on the non-shared node and are not related to each other. Once a node fails over, it will switch to that shared inactive node.
This structure is a scheme between "active/inactive" and "active/active". Compared with "active/inactive", he wastes less node resources (1/N+1). In addition, if two or more nodes fail over at the same time, the probability of switching to a shared node at the same time is relatively low, so the performance problem of the "active/active" structure is solved to a certain extent.
The picture is as follows:
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