Within the context of database mirroring, the mirror server acts as the failover partner for the principal server. In the event of a disaster, the mirror server takes over the role of the principal server, bringing the mirror copy of the database online as the new principal database. The former principal server, if available, then assumes the role of the mirror server. This process, known as role switching, can take the form of:
-
Automatic failover: If the principal server becomes unavailable, quickly brings the mirror copy of the database online as the new principal database.
-
Manual failover: Allows the database owner to reverse the roles of the failover partners, if necessary.
-
Forced service: If the principal server becomes unavailable, allows the database owner to restore access to the database by forcing the mirror server to take over the role of the principal server.
In any role switching scenario, as soon as the new principal database comes online, the Administration Service can recover by automatically reconnecting to the database.
For more information about the database mirroring technology, and instructions on how to set up and administer database mirroring on SQL Server, see the Database Mirroring in the SQL Server product documentation.
NOTE: The Active Roles replication function is not supported for the databases that have mirroring set up. If you attempt to perform the Promote to Publisher or Add Subscriber operation on such a database, you receive an error.
This section is based on the assumption that mirroring for the database of Active Roles is already set up on the SQL Server side in accord with the recommendations and instructions found in Microsoft’s documentation, so that the following conditions are fulfilled:
-
The Administration Service is connected to the Configuration database on the principal database server.
-
Replication is not configured for the Configuration database (the database server acts as a stand-alone server as applied to Active Roles replication).
-
The Administration Service is connected to the Management History database on the principal database server (by default, the Management History database is the same as the Configuration database).
-
Replication is not configured for the Management History database (the database server acts as a stand-alone server as applied to Active Roles replication).
Under these conditions, the Administration Service can be instructed to automatically connect to the new principal database in the event of database server role switching. On the computer running the Administration Service, add a string value to each of these two registry keys, and then restart the Administration Service:
-
Key: HKLM\SOFTWARE\One Identity\Active Roles\8.2.1\Service\DatabaseConnectionString\
Value Name: Failover Partner
Value Data: <Identifies the SQL Server instance that currently owns the mirror server role for the Configuration database>
-
Key: HKLM\SOFTWARE\One Identity\Active Roles\8.2.1\Service\CHDatabaseConnectionString\
Value Name: Failover Partner
Value Data: <Identifies the SQL Server instance that currently owns the mirror server role for the Management History database>
If the default instance is used, the value data is the short name of the computer running SQL Server. Otherwise, the value data is the short name of the computer, followed by a backslash (\), followed by the name of the instance, for example, ComputerName\InstanceName.
By default, the same database is used for the Configuration and Management History data; therefore, the value data would be the same in the DatabaseConnectionString and CHDatabaseConnectionString keys.
To restart the Administration Service, open Configuration Center and click Restart at the top of the Administration Service page in the Configuration Center main window. For more information on how to run Configuration Center, see Running Configuration Center.
To view the mirroring status of the Configuration or Management History database that is used by a particular instance of the Administration Service in the Active Roles Console
-
In the Console tree, select Configuration > Server Configuration > Administration Services.
-
In the Details pane, double-click the name of the Administration Service whose database you want to examine.
-
In the Properties dialog, click the Configuration Database or Management History Database tab, and view the information in the Database mirroring area:
-
Role: Current role of the database in the database mirroring session (Principal or Mirror).
-
Partner: The instance name and computer name for the other partner in the database mirroring session.
-
State: Current state of the mirrored database and of the database mirroring session. For more information about this field, see Mirroring States.
If no information is displayed in the Database Mirroring area, it means that the database mirroring is not configured.
You can also view the mirroring status of a Configuration database or a Management History database on the General tab in the Properties dialog for the object representing that database in the Configuration/Server Configuration/Configuration Databases or Configuration/Server Configuration/Management History Databases container, respectively.
When configuring replication, Active Roles automatically sets replication parameters to the appropriate values. This ensures that replication is functioning properly. Normally, there is no need to modify the replication settings except for some error situations outlined in Troubleshooting replication failures.
The following table lists the values that Active Roles assigns to certain replication parameters.
Table 81: Values assigned to Replication parameters
Publication name |
AelitaReplica |
Replication type |
Merge |
Subscription type |
Push |
Subscription expiration |
Subscriptions expire and may be dropped if not synchronized in 60 days. |
Schedule |
The Merge Agents are running continuously at the Publisher. The Snapshot Agent starts daily at 00:00 at the Publisher. |
To view the replication parameters using SQL Server Management Studio,
|
CAUTION: Do not change these settings. Replication might not work correctly if you manually modify replication settings with the use of SQL Server tools. |
-
Start Management Studio and connect to the Publisher SQL Server:
-
In Object Explorer, click Connect, and then click Database Engine.
-
Complete the Connect to Server dialog to connect to the instance of the SQL Server Database Engine that holds the Publisher role.
-
Open the Publication Properties dialog:
-
In Object Explorer, under the Publisher SQL Server, expand Replication > Local Publications.
-
In Object Explorer, under Local Publications, right-click AelitaReplica, and click Properties.
In the Publication Properties dialog, you can review the Active Roles publication settings.
-
Open the Subscription Properties dialog:
-
In Object Explorer, under Local Publications, expand AelitaReplica.
-
In Object Explorer, under AelitaReplica, right-click a Subscription, and click Properties.
In the Subscription Properties dialog, you can review the Active Roles subscription settings.
By default, Active Roles schedules the Replication Agents to run at the Publisher as follows:
-
The Snapshot Agent starts every day at 00:00.
-
The Merge Agents start automatically when SQL Server Agent starts, and runs continuously.
To verify the Snapshot Agent schedule
-
Open SQL Server Management Studio.
- In Object Explorer, connect to the instance of the SQL Server Database Engine that holds the Publisher role, and then expand that instance.
- Right-click the Replication folder, and click Launch Replication Monitor.
- In the left pane of the Replication Monitor window, expand your Publisher SQL Server, and click AelitaReplica.
-
In the right pane of the Replication Monitor window, on the Warnings and Agents tab, right-click the Snapshot Agent in the Agents and jobs related to this publication list, and click Properties.
- In the left pane of the Job Properties window, click Schedules.
- Review the Replication Agent schedule settings in the right pane of the Job Properties window.
- To view the Replication Agent schedule settings in detail, click Edit.
To verify the Merge Agent schedule
-
Open SQL Server Management Studio.
- In Object Explorer, connect to the instance of the SQL Server Database Engine that holds the Publisher role, and then expand that instance.
- Right-click the Replication folder, and click Launch Replication Monitor.
- In the left pane of the Replication Monitor window, expand your Publisher SQL Server, and click AelitaReplica.
-
In the right pane of the Replication Monitor window, on the All Subscriptions tab, right-click the subscription whose Merge Agent you want to examine, and click View Details.
-
In the Subscription window, on the Action menu, click Merge Agent Job Properties.
- In the left pane of the Job Properties window, click Schedules.
- Review the Replication Agent schedule settings in the right pane of the Job Properties window.
- To view the Replication Agent schedule settings in detail, click Edit.