SQL Server Distributed AG's Forwarder Is Not Syncing After Primary AG's Internal Failover
I have set up a SQL Server Distributed Availability Group (DAG) in Kubernetes using SQL Server on Ubuntu images. The setup consists of two availability groups (AGs) across two separate clusters: Setup Details: Primary Cluster (AG1) Pods: ag1-0 (Primary), ag1-1, ag1-2. The Primary is Exposed via the LoadBalancer service. Remote Cluster (AG2): Pods: ag2-0 (The Primary of AG2, Acting as a forwarder of DAG), ag2-1, ag2-2. The Forwarder (ag2-0) is Exposed via the LoadBalancer service. Distributed AG Configuration: AG1 and AG2 are part of the DAG. Each AG’s primary is dynamically selected using the pod's label role=primary. LISTENER_URL in the DAG configuration points to the LoadBalancer service of each AG. Issue: DAG Not Syncing After AG1 Failover For testing, I triggered a failover in AG1 using: `ALTER AVAILABILITY GROUP [AG1] FORCE_FAILOVER_ALLOW_DATA_LOSS;` The global primary changed from ag1-0 to ag1-1, and I updated the role=primary label accordingly (removed from ag1-0, added to ag1-1. However, AG2 (the forwarder and its replicas) stopped syncing and became unhealthy. From ag2-0 (forwarder) logs, I only see connection timeouts and disconnections from the global primary. AG2 is not automatically reconnecting to the new primary (ag1-1), even though the LoadBalancer service in LISTENER_URL now points to ag1-1. Logs from ag2-0 (Forwarder) Shows Like A connection timeout has occurred while attempting to establish a connection to GLOBAL PRIMARY. Either a networking or firewall issue exists, or the endpoint address provided for the replica is not the database mirroring endpoint of the host server instance Steps I Tried: - Checked DAG Configuration – The LISTENER_URL is correctly set to the LoadBalancer of AG1, which now points to ag1-1. - Ran the Resume Command: `ALTER DATABASE [agtestdb] SET HADR RESUME;` This did not resolve the issue. - Verified Network Connectivity Questions: - What steps are required to ensure AG2 correctly syncs with the new global primary (ag1-1) after an AG1's internal failover? - Is there a specific command that needs to be run on the forwarder (ag2-0) or the new global primary (ag1-1) to reestablish synchronization? - Why isn’t AG2 automatically reconnecting, even though the LoadBalancer service points to the correct primary? - Are there any best practices for handling SQL Server DAG failovers in Kubernetes? Any insights would be greatly appreciated!Lesson Learned #37: How to use distributed transactions in Azure SQL Database
First published on MSDN on Mar 30, 2018 Currently, there is not possible to update two tables of different databases using a single transaction in Azure SQL Database in the same way that we have in SQL ServerIf you need to implement in your code a distributed transactions, your application will the coordinator of this distributed transaction using the transaction scope method using .
