vCloud Automation Center – vCAC 5.1 – Reservations Demystified

Caution: Articles written for technical not grammatical accuracy, If poor grammar offends you proceed with caution ;-)

I have written a few articles that show you how to configure “Reservations” in vCAC. In this article I’m going to dig in to some details around “Reservations”, how they work, and the additional options that are available for them.

What are Reservations?

Reservations are a way for Enterprise Administrators to provide a subset of resources to the users within the organization. When a reservation is created it is assigned to a specific Provisioning Group and only a single Provisioning Group. They are a construct within vCAC and are not related to “Resource Pools” in vCenter. They can however be mapped to one which we will discuss. There are (3) primary types of Reservations:

  • Virtual Reservations
  • Cloud Reservations
  • Physical Reservations

Virtual Reservations

Virtual Reservations are used to allocate resources for the following:

  • VMware vSphere
  • VMware vCloud Director
  • Hyper-V Hosts
  • Hyper-V managed by SCVMM
  • Xen Server

Virtual Reservations have (3) parts to them. Reservation Information, Resources, and Alerts.

Reservation Information

The Reservation Information Screen includes the following:

  • Compute Resource – Here you select the “Compute Resource” you want to carve out resources from. This can be any of the Virtual Resources you have in your environment.
  • Name – This is the name your Reservation will have. Initially vCAC auto-generates a name, but you can override and use your own if you like.
  • Reservation Policy – We will discuss Reservation Policies as it’s own topic but for now think of them as a way of tagging Reservations.
  • Machine Quota – Here you can optionally define a specific number of machines that can be deployed against this reservation. Very useful if you are trying to maintain a specific consolidation ration.
  • Priority – Priorities help you determine how to consume resources. Let’s say you are building out PODs in your environment and they are all capable of hosting the same type of workloads. Essentially these PODs are Clusters and you need to determine how you want to consume the resources on each POD. Do you fill one POD and let the other two sit running and unused, or do you fill them all evenly distributing the load. The choice is really yours if you had reservations against all three PODs assigned to a group you could weight them Evenly and evenly distribute the request across all reservations, or you could weight them Unevenly, say 1, 2, & 3. vCAC will fill the Priority 1 reservation first, then the priority 2, and then the priority 3.
  • Custom properties – I will discuss Custom properties and their uses in a separate article.


The Resources Screen allows us to define the “Resources” that will be made available as part of this reservation. Configuration options include:

  • Memory – Allows you to allocate the amount of Memory the Group has to consume as part of this reservation.
  • Storage – Here you can determine which datastores are available, and how much of each the group can consume. You will also notice the “Priority” setting which works just like the Reservation Priority but for the datastores.
  • Networks – The Networking selection allows you to restrict the group to placing machine only on the networks that you allow them access to.
  • Resource Pools – These are very specific to vSphere clusters. It allows you to map a vCAC Reservation to a vCenter Resource Pool if they are in use. vCAC does not modify the pool settings, it is only used to place a provisioned machine into the Pool if it is selected as part of the Reservation.


Alerts are exactly how they sound. They allow you to set thresholds and who to notify when certain aspects of the Reservation become a certain percentage consumed.

Virtual vCloud Director Reservations

vCloud Director Reservations are different from most other virtual reservations. When creating a vCloud Director virtual reservation you already have a defined pool of resources that has been imported from vCloud Director called an Organizational Virtual Data Center or oVDC. The entire oVDC get’s assigned to a group through a reservation and cannot be carved up like other types of virtual reservations.

Cloud Reservations

Cloud Reservations are very specific to Amazon EC2 when it comes to the “Resources” that are assigned tot he group through the Reservation, but the “Reservation Information” and “Alerts” areas as the same as Virtual Reservations.

Cloud Reservation Resources


  • Key Pair – Allows you to determine how you want to manage AWS key pairs for you machine running on EC2
  • Assign to a subnet in a VPC – If you are utilizing Amazons “Virtual Private Cloud” offering you can map the reservation to a pre-configured VPC location.
  • vcacres-5

  • Locations – Allows you to select from the environments available within the Amazon Region the Compute Resource is located.
  • Security Groups – Allow you to select the AWS security Groups you want to make available to the group.
  • Load Balancers – This allows you to make specific load balancers available to the groups for use.

Physical Reservations

Physical reservations allow you to assign pools of physical assets to groups. These assets could be HP Servers, Dell Server, or Cisco UCS Blades. Essentially you create a Physical Reservation assign it the physical assets and then the groups users can select form those physical assets when making a request. Much like the other reservations the “Resource Information” and “Alerts” are fairly similar with the “Resources” information being very specific to “Physical”

Leave a Reply