We have a SQL Server 2016 cluster with 4 Always On groups. We had an unscheduled failover this morning and one of the groups did not come back online.
AG1 had databases that needed to rollback many transactions and that group failed over to the DR node while the original primary node performed the rollback
AG3 is a test group
AG4 is a new one and not currently used
AG2 was the problem group with small databases. 3/5 databases are in not synchronizing mode and i'm unable to force it manually. SSMS said it failed over to the secondary node but the databases stayed in not synchronizing mode. After a while we restarted the original primary node to see if we can hurry things up but then AG2 went into resolving mode on it and stayed that way.
I'm waiting for a database in AG1 to finish it's rollback, but is there a reason why AG2 will not come up and synchronize all databases?
The only clue I have is a Failover Clustering error 1254 that says the group exceeded it's failover threshold.