Monitoring SQL Server Database Mirroring with Email Alerts

Problem
The number of Database Mirror pairs in our enterprise is increasing at an alarming rate. With the ease of setup, resilience and ability to seamlessly failover and failback, database mirroring has taken over from log shipping as the DR solution of choice. We need a basic script that we can execute on all servers participating in mirroring that will alert us if any Principals or Mirrors are in an abnormal state. The script needs to work on both Principal and Mirror server.

Solution
The Catalog View sys.database_mirroring contains one row for each database in the instance of SQL Server and also contains state information of all mirrored databases. We'll query this Catalog View and raise an email alert for each mirrored database that we find in an abnormal state. We don't utilize a witness server in any of our mirrored pairs so we rely on manual failover.

Substitute in the below script your Database Mail profile and a suitable email address to receive the alerts.

DECLARE @state VARCHAR(30)

DECLARE @DbMirrored INT

DECLARE @DbId INT

DECLARE @String VARCHAR(100)

DECLARE @databases TABLE (DBid INT, mirroring_state_desc VARCHAR(30))

-- get status for mirrored databases

INSERT @databases

SELECT database_id, mirroring_state_desc

FROM sys.database_mirroring

WHERE mirroring_role_desc IN ('PRINCIPAL','MIRROR')

AND mirroring_state_desc NOT IN ('SYNCHRONIZED','SYNCHRONIZING')

-- iterate through mirrored databases and send email alert

WHILE EXISTS (SELECT TOP 1 DBid FROM @databases WHERE mirroring_state_desc IS NOT NULL)

BEGIN

SELECT TOP 1 @DbId = DBid, @State = mirroring_state_desc

FROM @databases

SET @string = 'Host: '+@@servername+'.'+CAST(DB_NAME(@DbId) AS VARCHAR)+ ' - DB Mirroring is '+@state +' - notify DBA'

EXEC msdb.dbo.sp_send_dbmail 'valid_mail_profile', 'DBA@mssqltips.com', @body = @string, @subject = @string

DELETE FROM @databases WHERE DBid = @DbId

END

--also alert if there is no mirroring just in case there should be mirroring :)

SELECT @DbMirrored = COUNT(*)

FROM sys.database_mirroring

WHERE mirroring_state IS NOT NULL

IF @DbMirrored = 0

BEGIN

SET @string = 'Host: '+@@servername+' - No databases are mirrored on this server - notify DBA'

EXEC msdb.dbo.sp_send_dbmail 'valid_mail_profile', 'DBA@mssqltips.com', @body = @string, @subject = @string

END

To verify the alert let's pause mirroring through the SQL Server Management Studio (SSMS). In Object Explorer right click your mirrored database -> Properties -> Mirroring option -> Pause button as follows:

Now, if the query finds a mirrored database in an abnormal state as shown below, it will send out an alert email alert:

The script will also output the following information to notify you that an alert has been sent to be processed by Database Mail.

Email received that clearly shows the host name, database name and the abnormal state of the mirroring so that the DBA team can investigate further.