Azure Active Directory Connect high-availability using ‘Staging Mode’

With the Azure Active Directory Connect product (AAD Connect) being announced as generally available to the market (more here, download here), there is a new feature available that will provide a greater speed of recovery of the AAD Sync component. This feature was not available with the previous AAD Sync or DirSync tools and there is little information about it available in the community, so hopefully this model can be considered for your synchronisation design.

Even though the AAD Sync component within the AAD Connect product is based on the Forefront Identity Manager (FIM) synchronisation service, it does not take on the same recovery techniques as FIM. For AAD Sync, you prepare two servers (ideally in different data centres) and install AAD Connect. Your primary server would be configured to perform the main role to synchronise identities between your Active Directory and Azure Active Directory, and the second server installed in much the same way but configured with the setting ‘enable staging mode’ being selected. Both servers are independent and do not share any components such as SQL Server, and the second server is performing the same tasks as the primary except for the following:

• No exports occur to your on-premise Active Directory
• No exports occur to Azure Active Directory
• Password synchronisation and password writeback are disabled.

Should the primary server go offline for a long period of time or become unrecoverable, you can enable the second server by simply running the installation wizard again and disabling staging mode. When the task schedule next runs, it will perform a delta import and synchronisation and identify any differences between the state of the previous primary server and the current server.

Some other items you might want to consider with this design.

• Configure the task schedule on the second server so that it runs soon after the primary server completes. By default the task schedule runs every 3 hours and launches at a time which is based on when it was installed, therefore the second server task schedule can launch up to a few hours after the primary server runs. Based on the average amount of work the primary server takes, configure the task schedule on the second server to launch say 5-10 minutes later
• AAD Sync includes a tool called CSExportAnalyzer which displays changes that are staged to be exported to Active Directory or Azure Active Directory. This tool is useful to report on pending exports while the server is in ‘staging mode’
• Consider using ‘custom sync groups’ which are located in your Active Directory domain. The default installation of the AAD Sync component will create the following groups locally on the server: ADSyncAdmins, ADSyncOperators, ADSyncBrowse and ADSyncPasswordSet. With more than one AAD Sync server, these groups need to be managed on the servers and kept in sync manually. Having the groups in your Active Directory will simplify this administration.

  NOTE: This feature is not yet working with the current AAD Connect download and this blog will be updated when working 100%.

The last two items will be detailed in future blogs.