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Violation of AlwaysOn constraint

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Rakesh configures WSFC cluster with two nodes, NODE01 and NODE02. He installs a SQL Server failover cluster instance, fciInstance1, on both NODE01 and NODE02 where NODE01 is the current owner for fciInstance1.

On NODE02, Rakesh installs another instance of SQL Server, Instance3, which is a stand-alone instance.
On NODE01,  Rakesh  enables fciInstance1 for AlwaysOn Availability Groups. On NODE02, he enables Instance3 for AlwaysOn Availability Groups. Then he sets up an availability group for which fciInstance1hosts the primary replica, and Instance3 hosts the secondary replica.
At some point fciInstance1 becomes unavailable on NODE01, and the WSFC cluster causes a failover of fciInstance1 to NODE02. After the failover, fciInstance1 is a AlwaysOn Availability Groups-enabled instance running under the primary role on NODE02. However, Instance3 now resides on the same WSFC node as fciInstance1. This violates the AlwaysOn Availability Groups constraint.





Detailed Explanation in this blog:-


http://blogs.msdn.com/b/arvindsh/archive/2012/09/26/failover-cluster-instance-alwayson-availability-group-dr-scenario.aspx

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