Microsoft SQL Server provides many options for high availability, including failover clustering using Microsoft Cluster Service, SQL Server Replication, SQL Server Database Mirroring, and SQL Server Log Shipping. Clustering would allow for the least amount of downtime, but replication, database mirroring, and log shipping can also be used to satisfy other needs such as the need for a reporting environment to lessen the load on your production (transactional) server. The high availability option you select for the Microsoft Dynamics AX implementation will depend on your availability requirements, on a cost/benefit analysis, and on the risk tolerance of your organization.

Important Important

Before deciding on a SQL Server high availability option, it is important to contact your value added reseller (VAR) or Microsoft Support to ensure that your planned option is supported.

It is important to determine and document carefully your availability needs, and to test the solution to make sure it provides the expected availability. The following table lists supported and non-supported high-availability configurations.

High-availability configuration

Support status

Failover clustering active/passive


Log shipping


Transactional replication


Snapshot replication


Database mirroring


Merge replication

Not supported due to complex resolution required to ensure data integrity

Failover clustering active/active

Not supported due to complex resolution required to ensure data integrity

We recommend deploying an Active/Passive Failover Cluster as it will not require a restart of the Application Object Server (AOS) service. The figure below shows a SQL Server failover topology.

When using SQL Server failover clustering, note the following:

  • The failover is transparent to the AOS and the service should not require a restart.

  • “In-flight” transactions are rolled back and the user may have to reenter data that was being entered at the time of failure.

Note Note

Active/passive failover clustering is tested and supported, whereas active/active clustering is not supported due to the complex conflict resolution required to ensure data integrity.

Caution note Caution

SQL Server Reporting Services and SQL Server Analysis Services are not supported in a failover cluster.