Overview of an SQL Server AG as a Target

If an SQL Server Availability Group configuration is set on a cluster, it will be discovered whenever such a cluster is added as a Windows target environment on the Delphix Continuous Data Engine. The discovered AG configuration is not visible on UI and can be verified by listing repositories on the CLI.

Delphix Engine requires an AG listener to discover the AG configuration and existing availability databases. For more details on discovering AG configuration refer to the following section:

  • Supported roles for Failover Cluster instances and Always On Availability Groups

  • Common requirements for failover cluster target environments

  • Requirements for failover cluster target environments with SQL Server Availability groups added as target environments

 

 

The AG repository discovered on delphix engine is used for the provisioning of virtual databases (VDB). Such a VDB, provisioned on an AG configuration, will be called an AG virtual database container or AG VDB in short.

The Delphix AG virtual database container is similar to an availability database on SQL Server. An AG virtual database container is a logical entity that comprises of multiple replica database containers. Replica database containers represent the actual SQL Server databases that are hosted on Delphix storage mounted on every AG replica host.

Thus, one of the replica database containers represents a primary database of the Availability group at all times and the rest of the replica database containers act as secondary databases of the Availability group.

Support Matrix for VDB operations across different VDB types 

 

Common VDB operations 

 

Provision 

Refresh 

Disable/Enable 

Delete 

Auto VDB Restart 

Snapshot 

Stop/Start

Rewind 

V2P

Undo Refresh 

VDB on standalone instances 

Y 

Y 

Y 

Y 

Y 

Y 

Y 

Y 

Y 

Y 

VDB on FCI 

Y 

Y 

Y* 

Y 

Y 

Y 

Y 

Y 

Y 

Y 

VDB on AG 

Y 

Y 

Y* 

Y 

Y 

N 

N 

N 

N 

N 

* Force Disable is not supported for VDB on FCI or VDB on AG

For more details on unsupported operations, refer to SQL Server AG as Target database limitations.