This monitor checks the status of the database mirroring witness as reported by Microsoft® SQL Server™. This is performed by running a query against the master database of the SQL Server instance and returning the state of the database mirroring witness. If you receive an alert from this monitor, an action is required in order to bring the database mirroring witness back to an operational state.
Unhealthy state indicates that the SQL Server™ database mirroring witness is currently unavailable. All states except CONNECTED and NO-WITNESS will cause Unhealthy state. The possible states are detailed below:
Mirroring Witness State
MOM Health State
This is normal operational state. Mirroring Partner can access the Witness server.
This state indicates that there is no Witness specified for the mirroring session. It is normal operational state for High-Performance Mode and High-Safety Mode Without Automatic Failover.
There are some issues with connection between Mirroring Partner and Witness server.
There is no connection between Mirroring Partner and Witness server.
To resolve the issue try the following:
Make sure mirroring configuration is complete and mirroring process is up and running.
Check physical link between Mirroring Partner and Witness server.
Configure firewall rules on both servers according to endpoints configuration.