Active Roles uses the replication functionality of Microsoft SQL Server to copy and distribute configuration data from one Administration Service database to another, and to synchronize data among the databases for consistency.
Administration Service database servers synchronized by using the SQL Server replication function are referred to as replication partners. Each replication partner maintains a writable copy of the Service’s configuration and Management history data. Whenever changes are made to one replication partner, the changes are propagated to the other replication partners.
The replication group
The Publisher and its Subscribers constitute a replication group. Every replication group must include a single Publisher and may include any number of Subscribers. The members of a replication group are referred to as replication partners.
Each member of a replication groups (replication partner) maintains a separate, writable copy of the Administration Service’s configuration and management history data. Replication copies and distributes data from one member database to another, and synchronizes data between the databases for consistency. When changes are made on the Publisher, the Publisher replicates these changes to each Subscriber. When data changes are made on a Subscriber, the Subscriber propagates the changes to the Publisher, which in turn replicates them to the other Subscribers.
This replication process ensures the same configuration for all Administration Services that use the database servers belonging to the replication group.
When initially set up, the Administration Service database server is configured as a standalone database, that is, it does not have replication partners and does not belong to any replication group. The Administration Service that uses a standalone database server is referred to as standalone Administration Service.
It is possible to add a standalone database server to any replication group that already exists. When you do that, the database server becomes a Subscriber. Each Administration Service database server may belong to only one replication group. Once removed from a replication group, it can be added to a different group.
To create a new replication group, a standalone database server must be designated as the Publisher. The new replication group will then have a single member—the Publisher. Later, you may add Subscribers to the group.
If there are any replication failures in Active Roles, the Active Roles console provides a visual indication of this issue by modifying the icon of the Server Configuration and Configuration Databases containers in the console tree: a label with the exclamation point appears next to each of the containers. This allows the administrator to detect a replication failure without examining individual replication partners.
Creating a replication group
To create a replication group, designate a standalone Administration Service database server as the Publisher. You can do that by using the Active Roles console:
- Connect to a standalone Administration Service.
- Promote the Administration Service database server to Publisher.
To connect to the Administration Service, use the instructions provided earlier in this chapter (see Connecting to the Administration Service).
Once connected to the Administration Service, perform the following steps to promote the Administration Server database server to Publisher:
- In the console tree, navigate to the Configuration/Server Configuration/Configuration Databases container.
- In the details pane, right-click the database and click Promote.
NOTE: The Promote command is only displayed if the Administration Service uses a standalone database server, that is, a database server that does not belong to any replication group.
After you click Promote, it takes several minutes to complete the operation. When the operation is completed, the new replication group has a single member—the Publisher. Once the replication group has been created, you can add replication partners—Subscribers.
After the Promote operation is completed, both the configuration and management history databases are replicated.
If Active Roles does not have sufficient rights to perform the Promote operation on SQL Server, then the Active Roles console prompts you to supply an alternative account for that operation (see “Permissions for creating or removing the Publisher” in the Active Roles Quick Start Guide).
Adding members to a replication group
To add a member to a replication group, designate a standalone database server as a Subscriber of the group’s Publisher. You can do that by using the Active Roles console:
- Connect to the Publisher Administration Service.
- Start and complete the New Replication Partner wizard.
Once connected to the Publisher Administration Service, display the contents of the Configuration Databases container. The details pane lists the names of the Publisher and its Subscribers. Right-click the Publisher and click Add Replication Partner. Then, follow the instructions in the New Replication Partner wizard.
On the Database Selection page, click Browse to select the Administration Service that uses the database server you want to designate as a Subscriber. Clicking Browse displays the dialog box similar to that described in the Connecting to the Administration Service section earlier in this chapter. Type the name of the computer running the Administration Service, or select it from the list.
The wizard automatically selects the database server that hosts the database of the Administration Service you specify. If Active Roles does not have sufficient rights to perform the Add Replication Partner operation on SQL Server, then the wizard prompts you to supply an alternative account for that operation (see “Permissions for adding or removing a Subscriber” in the Active Roles Quick Start Guide).
The next page of the wizard displays the database name and location retrieved from the specified Administration Service, and prompts you to select one of the following options that determine how the replication agent running on the Publisher SQL Server will connect to the Subscriber SQL Server:
- Impersonate SQL Server Agent service account Use this option if the SQL Server Agent service on the Publisher SQL Server is configured to log on as a Windows user account that has sufficient rights on the Subscriber SQL Server. If this option is selected, the replication agent connects to the Subscriber SQL Server under the logon account of the SQL Server Agent service running on the Publisher SQL Server.
- Use SQL Server Authentication with the following login and password Use this option if the SQL Server Agent service logon account cannot be configured to have sufficient rights on the Subscriber SQL Server. You are prompted to specify the SQL Server login and password that the replication agent running on the Publisher SQL Server will use to connect to the Subscriber SQL Server.
The account that the replication agent uses to connect to the Subscriber SQL Server must at minimum be a member of the db_owner fixed database role in the subscription database (Active Roles’ database on the Subscriber). For further details, see “Replication agent permissions” in the Active Roles Quick Start Guide.
The completion page of the wizard allows you to review summary information about the database server you are going to make a Subscriber. After you click Finish, the database server is added to the replication group. The replication process updates the database of the new Subscriber with the data retrieved from the Publisher.
IMPORTANT: The Publisher copies new data to the database, overwriting the existing data. If the database contains valuable information, such as custom Access Templates or Policy Objects, you should export those objects before designating the database server as a Subscriber, and import them back after the operation is completed.