Setup Geographic Redundancy with SQL Server Replication

 

Important

If you want to create an AD FS farm and use SQL Server to store your configuration data, you can use SQL Server 2008 and newer versions, including SQL Server 2012, and SQL Server 2014.

If you are using SQL Server as your AD FS configuration database, you can set up geo-redundancy for your AD FS farm using SQL Server replication. Geo-redundancy replicates data between two geographically distant sites so that applications can switch from one site to another. This way, in case of the failure of one site, you can still have all the configuration data available at the second site. For more information, see the “SQL Server geographic redundancy section” in Federation Server Farm Using SQL Server2.

Prerequisites

Install and configure a SQL server farm. For more information, see http://technet.microsoft.com/evalcenter/hh225126.aspx. On the initial SQL Server, make sure that the SQL Server Agent service is running and set to automatic start.

Create the second (replica) SQL Server for geo-redundancy

  1. Install SQL Server (for more information, see http://technet.microsoft.com/evalcenter/hh225126.aspx). Copy the resulting CreateDB.sql and SetPermissions.sql script files to the replica SQL server.

  2. Ensure SQL Server Agent service is running and set to automatic start

  3. Run Export-AdfsDeploymentSQLScript on the primary AD FS node to create CreateDB.sql and SetPermissions.sql files. For example:PS:\>Export-AdfsDeploymentSQLScript -DestinationFolder . –ServiceAccountName CONTOSO\gmsa1$.

  4. Run the scripts in SQL by executing the following at a command prompt on the replica SQL server (logged in as domain admin or other SQL server admin):

    c:\>sqlcmd –i CreateDB.sql

    c:\>sqlcmd –i SetPermissions.sql

Create publisher settings on the initial SQL Server

  1. From the SQL Server Management studio, under Replication, right click Local Publications and choose New Publication...

  2. On Distributor page, choose local server as distributor.

  3. On the Snapshot folder page, enter \\db1\repldata\ in place of default folder. (NOTE: You may have to create this share yourself).

  4. Choose AdfsConfiguration as the publication database.

  5. On Publication Type, choose Merge.

  6. On Subscriber Types, choose SQL Server 2008 or later (the default).

  7. On the Articles page select Tables node to select all tables, then un-check SyncProperties table (this one should not be replicated)

    Default article properties include bidirectional and row-level tracking.

  8. On the Articles page, select User Defined Functions node to select all User Defined Functions.

  9. On the Article issues page, there will be two issues reported: one about adding GUIDs to all tables, and the other about ensuring database objects referenced by stored procedures will be on the replica system. Neither is a blocking issue so click Next.

  10. On the Filter Table Rows page, click Next.

  11. On the Snapshot Agent page, choose defaults of Immediate and 14 days, click Next.

    You may need to create a domain account for the SQL agent. Use the steps in Configure SQL login for the domain account CONTOSO\sqlagentto create SQL login for this new AD user and assign specific permissions.

  12. On the Agent Security page, click Security Settings and enter the username/password of a domain account (not a GMSA) created for the SQL agent.

  13. Leave default for Connect to the Publisher.

    Finish the wizard by naming the publication and then click Close.

  14. Right-click the new Publication and click Launch Replication Monitor.

Create subscription settings on the replica SQL Server

Make sure that you created the publisher settings on the initial SQL Server as described above and then complete the following procedure:

  1. On the replica SQL Server, from SQL Server Management studio, under Replication, right click Local Subscriptions and choose New Subscription....

  2. On the Publication page, enter the hostname\instancename of your publishing SQL server. Enter connection credentials if necessary to select the AdfsConfiguration publication created above.

  3. On the Merge Agent Location page, select Run each agent at its Subscriber (pull subscriptions) (the default).

    This, along with Subscription Type below, determines the conflict resolution logic. (For more information, see Detect and Resolve Merge Replication Conflicts.

  4. On the Subscribers page, enter AdfsConfiguration as the subscriber database.

  5. On the Merge Agent Security page, click ... and enter the username/password of a domain account (not a GMSA) created for the SQL agent. Leave defaults for Connect to the Publisher, Distributor, and Connect to the Subscriber.

  6. On Synchronization Schedule, choose Run Continuously.

  7. On Initialize Subscriptions, click Next to select the default Immediately.

  8. On Subscription Type, choose Client (the default).

    Implications of this are documented here and here. Essentially, we take the simple “first to publisher wins” conflict resolution and we do not need to republish to other subscribers.

  9. Finish the wizard, click Close.

Verify the process of initialization and replication

  1. On the primary SQL server, right-click the Replication node and click Launch Replication Monitor.

  2. In Replication Monitor, click the publication.

  3. On the All Subscriptions tab, right click and View Details.

    You should be able to see many entries under Actions for the initial replication.

  4. Additionally, you can look under the SQL Server Agent\Jobs node to see the job(s) scheduled to execute the operations of the publication/subscription. Only local jobs are shown, so make sure to check on the publisher and the subscriber for troubleshooting. Right-click a job and select View History to view execution history and results.

Configure SQL login for the domain account CONTOSO\sqlagent

  1. Create a new login on the primary and replica SQL Server called CONTOSO\sqlagent (the name of the new domain user created and configured on the Agent Security page in the procedures above.)

  2. In SQL Server, right-click the login you created, and select Properties, then under the User Mapping tab, map this login to AdfsConfiguration and AdfsArtifact databases with public and db_genevaservice roles. Also map this login to distribution database and add db_owner role for both distribution and adfsconfiguration tables. Do this as applicable on both primary and replica SQL server. For more information, see Replication Agent Security Model.

  3. Give the corresponding domain account read and write permissions on the share configured as distributor. Make sure that you set read and write permissions both on the share permissions and the local file permissions.

Configure AD FS node(s) to point to the SQL Server replica farm

Now that you have set up geo redundancy, the AD FS farm nodes can be configured to point to your replica SQL Server farm using the standard AD FS “join” farm capabilities, either from the AD FS Configuration Wizard UI or using Windows PowerShell.

If you use the AD FS Configuration Wizard UI, select Add a federation server to a federation server farm. Do NOT select Create the first federation server in a federation server farm.

If you use Windows PowerShell, run Add-AdfsFarmNode. Do NOT run Install-AdfsFarm.

When prompted, provide the host and instance name of the replica SQL Server, NOT the initial SQL server.

See Also

AD FS Operations