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Register todayDatabase Mirroring Witness Catalog Views - sys.database_mirroring_witnesses
Applies to: 
SQL Server
Contains a row for every witness role that a server plays in a database mirroring partnership.
In a database mirroring session, automatic failover requires a witness server. Ideally, the witness resides on a separate computer from both the principal and mirror servers. The witness does not serve the database. Instead, it monitors the status of the principal and mirror servers. If the principal server fails, the witness may initiate automatic failover to the mirror server.
| Column name | Data type | Description |
|---|---|---|
| database_name | sysname | Name of the two copies of the database in the database mirroring session. |
| principal_server_name | sysname | Name of partner server whose copy of the database is currently the principal database. |
| mirror_server_name | sysname | Name of the partner server whose copy of the database is currently the mirror database. |
| safety_level | tinyint | Transaction safety setting for updates on the mirror database: 0 = Unknown state 1 = Off (asynchronous) 2 = Full (synchronous) Using a witness for automatic failover requires full transaction safety, which is the default. |
| safety_level_desc | nvarchar(60) | Description of safety guarantee of updates on the mirror database: UNKNOWN OFF FULL |
| safety_sequence_number | int | Update sequence number for changes to safety_level. |
| role_sequence_number | int | Update sequence number for changes to principal/mirror roles played by the mirroring partners. |
| mirroring_guid | uniqueidentifier | Identifier of the mirroring partnership. |
| family_guid | uniqueidentifier | Identifier of the backup family for the database. Used for detecting matching restore states. |
| is_suspended | bit | Database mirroring is suspended. |
| is_suspended_sequence_number | int | Sequence number for setting is_suspended. |
| partner_sync_state | tinyint | Synchronization state of the mirroring session: 5 = The partners are synchronized. Failover is potentially possible. For information about the requirements for failover see, Role Switching During a Database Mirroring Session (SQL Server). 6 = The partners are not synchronized. Failover is not possible now. |
| partner_sync_state_desc | nvarchar(60) | Description of the synchronization state of the mirroring session: SYNCHRONIZED UNSYNCHRONIZED |
The visibility of the metadata in catalog views is limited to securables that a user either owns, or on which the user was granted some permission. For more information, see Metadata Visibility Configuration.
Database Mirroring Witness
sys.database_mirroring (Transact-SQL)
sys.database_mirroring_endpoints (Transact-SQL)
Querying the SQL Server System Catalog FAQ