We have a 4 node AG set up across two data centers using 4 replicas with a file share witness. Nodes 1 and 2 are in data center 1 and Nodes 3 and 4 in data center 2. Node 1 is primary and is set to synchronous commit with automatic failover to node 2 in the same datacenter. Node 1 is set to asynchronous commit to nodes 3 and 4 in data center 2. Node weighting is set to one for nodes 1 and 3 (main node in each data center) and zero for nodes 2 and 4.
Please, can someone tell me what the behavior would be if we had an unexpected SQL Server shut down at node 1?
Would the AG attempt to failover to node 3 in data center 2 due to the node weighting, fail and not attempt to fail over to any other replicas. Or would the AG group ignore node 3 due to it being async and try to fail over to the first synchronous replica with automatic failover based on the preferred owner's list?