Below is the script I use to monitor Always-ON
;WITH AG_Stats AS (
SELECT AGS.name AS AGGroupName,
AR.replica_server_name AS InstanceName,
HARS.role_desc,
Db_name(DRS.database_id) AS DBName,
DRS.database_id,
AR.availability_mode_desc AS SyncMode,
DRS.synchronization_state_desc AS SyncState,
DRS.last_hardened_lsn,
DRS.end_of_log_lsn,
DRS.last_redone_lsn,
DRS.last_hardened_time, -- On a secondary database, time of the log-block identifier for the last hardened LSN (last_hardened_lsn).
DRS.last_redone_time, -- Time when the last log record was redone on the secondary database.
DRS.log_send_queue_size,
DRS.redo_queue_size,
--Time corresponding to the last commit record.
--On the secondary database, this time is the same as on the primary database.
--On the primary replica, each secondary database row displays the time that the secondary replica that hosts that secondary database
-- has reported back to the primary replica. The difference in time between the primary-database row and a given secondary-database
-- row represents approximately the recovery time objective (RPO), assuming that the redo process is caught up and that the progress
-- has been reported back to the primary replica by the secondary replica.
DRS.last_commit_time
FROM sys.dm_hadr_database_replica_states DRS
LEFT JOIN sys.availability_replicas AR
ON DRS.replica_id = AR.replica_id
LEFT JOIN sys.availability_groups AGS
ON AR.group_id = AGS.group_id
LEFT JOIN sys.dm_hadr_availability_replica_states HARS ON AR.group_id = HARS.group_id
AND AR.replica_id = HARS.replica_id
),
Pri_CommitTime AS
(
SELECT DBName
, last_commit_time
FROM AG_Stats
WHERE role_desc = 'PRIMARY'
),
Rpt_CommitTime AS
(
SELECT DBName, last_commit_time
FROM AG_Stats
WHERE role_desc = 'SECONDARY' AND [InstanceName] = 'InstanceNameB-PrimaryDataCenter'
),
FO_CommitTime AS
(
SELECT DBName, last_commit_time
FROM AG_Stats
WHERE role_desc = 'SECONDARY' AND ([InstanceName] = 'InstanceNameC-SecondaryDataCenter' OR [InstanceName] = 'InstanceNameD-SecondaryDataCenter')
)
SELECT p.[DBName] AS [DatabaseName], p.last_commit_time AS [Primary_Last_Commit_Time]
, r.last_commit_time AS [Reporting_Last_Commit_Time]
, DATEDIFF(ss,r.last_commit_time,p.last_commit_time) AS [Reporting_Sync_Lag_(secs)]
, f.last_commit_time AS [FailOver_Last_Commit_Time]
, DATEDIFF(ss,f.last_commit_time,p.last_commit_time) AS [FailOver_Sync_Lag_(secs)]
FROM Pri_CommitTime p
LEFT JOIN Rpt_CommitTime r ON [r].[DBName] = [p].[DBName]
LEFT JOIN FO_CommitTime f ON [f].[DBName] = [p].[DBName]
