If you require maximum system robustness, configure your vRealize Automation system for high availability in accordance with VMware guidelines.
vRealize Automation Appliance
The vRealize Automation appliance supports active-active high availability for all components except the appliance database. Starting with the 7.3 release, database failover is automatic if three nodes are deployed and synchronous replication is configured between two nodes. When vRealize Automation appliance detects database failure, it promotes a suitable database server to be the master. You can monitor and manage the appliance database on the Virtual Appliance Management Console tab.
To enable high availability for these appliances, place them under a load balancer. For more information, see Configuring Your Load Balancer. Beginning with the 7.0 release, the appliance database, and vRealize Orchestrator are automatically clustered and available for use.
vRealize Automation Directories Management
Each vRealize Automation appliance includes a connector that supports user authentication, although only one connector is typically configured to perform directory synchronization. It does not matter which connector you choose to serve as the sync connector. To support Directories Management high availability, you must configure a second connector that corresponds to your second vRealize Automation appliance, which connects to your Identity Provider and points to the same Active Directory. With this configuration, if one appliance fails, the other takes over management of user authentication.
In a high availability environment, all nodes must serve the same set of Active Directories, users, authentication methods, etc. The most direct method to accomplish this is to promote the Identity Provider to the cluster by setting the load balancer host as the Identity Provider host. With this configuration, all authentication requests are directed to the load balancer, which forwards the request to either connector as appropriate.
For more information about configuring Directories Management for high availability, see Configure Directories Management for High Availability.
Infrastructure Web Server
The Infrastructure Web server components all support active-active high availability. To enable high availability for these components, place them under a load balancer.
Infrastructure Manager Service
The manager service component supports active-passive high availability. To enable high availability for this component, place two manager services under a load balancer. In vRealize Automation 7.3 and newer, failover is automatic.
If the active manager service fails, stop the Windows service, if it is not already stopped under the load balancer. Enable the passive manager service and restart the Windows service under the load balancer. See Install the Active Manager Service.
Agents support active-active high availability. For information about configuring agents for high availability, see the vRealize Automation configuration documentation. Check the target service for high availability.
Distributed Execution Manager Worker
A Distributed Execution Manager (DEM) running under the Worker role supports active-active high availability. If a DEM Worker instance fails, the DEM Orchestrator detects the failure and cancels workflows that the DEM Worker instance is running. When the DEM Worker instance comes back online, it detects that the DEM Orchestrator has canceled the workflows of the instance and stops running them. To prevent workflows from being canceled prematurely, leave a DEM Worker instance offline for several minutes before you cancel its workflows.
Distributed Execution Manager Orchestrator
DEMs running under the Orchestrator role support active-active high availability. When a DEM Orchestrator starts, it searches for another running DEM Orchestrator.
If it finds no DEM Orchestrator instances running, it starts running as the primary DEM Orchestrator.
If it does find another running DEM Orchestrator, it monitors the other primary DEM Orchestrator to detect an outage.
If it detects an outage, it takes over as the primary instance.
When the previous primary instance comes online again, it detects that another DEM Orchestrator has taken over its role as primary and monitors for failure of the primary Orchestrator instance.
MSSQL Database Server for Infrastructure Components
vRealize Automation supports SQL AlwaysON groups only with Microsoft SQL Server 2016. When installing SQL Server 2016, the database must be created in 100 mode. If you use an older version of Microsoft SQL Server, use a Failover Cluster instance with shared disks. For more information on configuring SQL AlwaysOn groups with MSDTC, see Microsoft article https://msdn.microsoft.com/en-us/library/ms366279.aspx.
An internal highly-available instance of vRealize Orchestrator is supplied as part of the vRealize Automation appliance.