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 DEM server runs the business logic of custom models by interacting with other vRealize Automation components 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, 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.

vRealize Automation IaaS DEM Workers are responsible for the executing provisioning and deprovisioning tasks initiated by the vRealize Automation portal. DEM Workers are also utilized to communicate with specific infrastructure endpoints.

The vRealize Automation IaaS Proxy Agent is a windows service used to communicate with specific infrastructure endpoints. In this design, the vSphere Proxy agent is utilized to communicate with vCenter.

The IaaS Proxy Agent server provides the following functions:

  • vRealize Automation IaaS Proxy Agent can interact with different types of infrastructure components. For this design, only the vSphere Proxy agent is used.

  • vRealize Automation does not itself virtualize resources, but works with vSphere to provision and manage the virtual machines. It uses vSphere Proxy agents to send commands to and collect data from vSphere.

Note:

The vRealize Automation IaaS Manager, DEM Orchestrator, DEM Worker and IaaS Proxy Agent are separate services, but in this design they are all installed on the same virtual machine.

Table 1. vRealize Automation IaaS Model Manager and DEM Orchestrator Server Design Decision

Decision ID

Design Decision

Design Justification

Design Implication

CSDDC-CMP-007

Deploy one virtual machine to run the vRealize Automation Manager Service, the DEM Orchestrator, the DEM Worker, and IaaS Proxy Agent services.

Co-locating the Manager service, DEM Orchestrator, DEM Worker and the IaaS Proxy Agent on a single VM provides the minimal footprint required for the consolidated pod. This design also provides for future expansion of the CMP to provide full application level HA.

Relies on vSphere HA for high availability of the application.

Table 2. vRealize Automation IaaS Model Manager and DEM Orchestrator Server Resource Requirements per Virtual Machine

Attribute

Specification

Number of vCPUs

4

Memory

8 GB

Number of vNIC ports

1

Number of local drives

1

vRealize Automation functions

Manager Service, DEM Orchestrator, DEM Worker and IaaS Proxy Agent.

Operating system

Microsoft Windows Server 2012 SP2 R2