The vRealize Automation IaaS Manager Service and Distributed Execution Management (DEM) server are at the core of the vRealize Automation IaaS platform. The vRealize Automation IaaS Manager Service and DEM server supports several functions.

Manages the integration of vRealize Automation IaaS with external systems and databases.

Provides business logic to the DEMs.

Manages business logic and execution policies.

Maintains all workflows and their supporting constructs.

A Distributed Execution Manager (DEM) runs the business logic of custom models by interacting with other vRealize Automation component (repository) as required.

Each DEM instance acts in either an Orchestrator role or a Worker role. The DEM Orchestrator monitors the status of the DEM Workers. If a DEM worker stops or loses the connection to the Model Manager or repository, the DEM Orchestrator puts the workflow back in the queue. It manages the scheduled workflows by creating new workflow instances at the scheduled time and allows only one instance of a particular scheduled workflow to run at a given time. It also preprocesses workflows before execution. Preprocessing includes checking preconditions for workflows and creating the workflow's execution history.

Note

The vRealize Automation IaaS Manager Service and DEM Orchestrator service are separate services, but are installed on the same virtual machine.

vRealize Automation IaaS Model Manager and DEM Orchestrator Server Design Decision

Decision ID

Design Decision

Design Justification

Design Implication

SDDC-CMP-008

Deploy two virtual machines to run both the vRealize Automation IaaS Model Manager and the DEM Orchestrator services in a load-balanced pool.

The Automation IaaS Model Manager and DEM Orchestrator share the same active/passive application model.

More resources are required for these two virtual machines to accommodate the load of the two applications. You can scale up the virtual machines later if additional resources are required.

vRealize Automation IaaS Model Manager and DEM Orchestrator Server Resource Requirements per Virtual Machine

Attribute

Specification

Number of vCPUs

2

Memory

4 GB

Number of vNIC ports

1

Number of local drives

1

vRealize Automation functions

Model Manager , DEM Orchestrator

Operating system

Microsoft Windows Server 2012 SP2 R2