vRealize Automation IaaS consists of one or more Windows servers that work together to model and provision systems in private, public, or hybrid cloud infrastructures.
You install vRealize Automation IaaS components on one or more virtual or physical Windows servers. After installation, IaaS operations appear under the Infrastructure tab in the product interface.
IaaS consists of the following components, which can be installed together or separately, depending on deployment size.
The IaaS Web server provides infrastructure administration and service authoring to the vRealize Automation product interface. The Web server component communicates with the Manager Service, which provides updates from the Distributed Execution Manager (DEM), SQL Server database, and agents.
vRealize Automation uses models to facilitate integration with external systems and databases. The models implement business logic used by the DEM.
The Model Manager provides services and utilities for persisting, versioning, securing, and distributing model elements. Model Manager is hosted on one of the IaaS Web servers and communicates with DEMs, the SQL Server database, and the product interface Web site.
The Manager Service is a Windows service that coordinates communication between IaaS DEMs, the SQL Server database, agents, and SMTP.
IaaS requires that only one Windows machine actively run the Manager Service. For backup or high availability, you may deploy additional Windows machines where you manually start the Manager Service if the active service stops.
Simultaneously running an active Manager Service on multiple IaaS Windows servers makes vRealize Automation unusable.
The Manager Service communicates with the Web server through the Model Manager and must be run under a domain account with administrator privileges on all IaaS Windows servers.
SQL Server Database
IaaS uses a Microsoft SQL Server database to maintain information about the machines it manages, plus its own elements and policies. Most users allow vRealize Automation to create the database during installation. Alternatively, you may create the database separately if site policies require it.
Distributed Execution Manager
The IaaS DEM component runs the business logic of custom models, interacting with the IaaS SQL Server database, and with external databases and systems. A common approach is to install DEMs on the IaaS Windows server that hosts the active Manager Service, but it is not required.
Each DEM instance acts as a worker or orchestrator. The roles can be installed on the same or separate servers.
DEM Worker—A DEM worker has one function, to run workflows. Multiple DEM workers increase capacity and can be installed on the same or separate servers.
DEM Orchestrator—A DEM orchestrator performs the following oversight functions.
Monitors DEM workers. If a worker stops or loses its connection to Model Manager, the DEM orchestrator moves the workflows to another DEM worker.
Schedules workflows by creating new workflow instances at the scheduled time.
Ensures that only one instance of a scheduled workflow is running at a given time.
Preprocesses workflows before they run. Preprocessing includes checking preconditions for workflows and creating the workflow execution history.
The active DEM orchestrator needs a strong network connection to the Model Manager host. In large deployments with multiple DEM orchestrators on separate servers, the secondary orchestrators serve as backups by monitoring the active DEM orchestrator, and provide redundancy and failover if a problem occurs with the active DEM orchestrator. For this kind of failover configuration, you might consider installing the active DEM orchestrator with the active Manager Service host, and secondary DEM orchestrators with the standby Manager Service hosts.