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aderossi avatar image
aderossi asked

What happens with ongoing process when cluster node fails

I'm planning to set up a SQL Server cluster with two nodes. But I'm not shure exactly what happens with some processes when one node fails. For example, if I have a long time running stored procedure executing at the time one node fails, when it fails over, the activating node continues the process? or is it rolled back and started again? Any links or articles will be appreciated Thanks in advance for your answers
clusterhigh-availability
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KenJ avatar image
KenJ answered
Functionally, a failover looks very similar to a service restart to all connected clients. All connections to the failed node are broken and their queries rolled back. Like a service restart, the connections are not automatically re-established and their queries do not automatically restart on the new node. The client application would have to reconnect and restart the query. For more information, start with the "AlwaysOn Failover Cluster Instances" topic in books online - http://msdn.microsoft.com/en-us/library/ms189134.aspx It has a broad outline of the failover sequence of events: 1. Unless a hardware or system failure occurs, all dirty pages in the buffer cache are written to disk. 2. All respective SQL Server services in the resource group are stopped on the active node. 3. The resource group ownership is transferred to another node in the FCI. 4. The new resource group owner starts its SQL Server services. 5. Client application connection requests are automatically directed to the new active node using the same virtual network name (VNN).
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