Monitoring alwayson Log Send Queue and Redo Queue
DMV’s sys.dm_hadr_database_replica_states & sys.availability_replicas provided the information on log send queue and redo Queue size
SELECT DB_NAME(database_id) AS dbname,ar.replica_server_name, CASE drs.is_local WHEN 0 THEN 'REMOTE' ELSE 'LOCAL' END AS is_local, drs.last_hardened_time, drs.log_send_queue_size / 1024 AS MB_log_SendQueueSize, drs.log_send_rate / 1024 AS MB_log_send_rate, drs.redo_queue_size / 1024 AS MB_redo_queue_size, drs.redo_rate / 1024 AS MB_redo_rate,drs.last_commit_time FROM sys.dm_hadr_database_replica_states drs join sys.availability_replicas ar on drs.group_id=ar.group_id and drs.replica_id=ar.replica_id