Organizations can draw resources from multiple organization virtual datacenters using one of the resource allocation models: Reservation Pool, Allocation Pool, or Pay As You Go.

Reservation Pool resources allocated to the organization virtual datacenter are completely dedicated. All guarantees are set to 100%. Reservation Pool virtual datacenters map to resource pools with the reservations set equivalent to the limits.

An allocation pool is a pool of allocated resources with a certain percentage of resources guaranteed. When an organization virtual datacenter is created using the Allocation Pool model, a dynamic resource pool is instantiated. This resource pool automatically adjusts available resources as new workloads are powered on based on the values specified within the virtual datacenter. Each value has a direct impact on how the related resource pool dynamically changes as new virtual machines are deployed. The following values are required when defining the size of an organization virtual datacenter.

 

An organization virtual datacenter is created with the following values:

After the organization virtual datacenter is created, a corresponding resource pool is created. Unlike versions of vCloud Director earlier than version 5.1, a reservation is not initially set on the resource pool. The resource settings are dynamically changed as each new virtual machine is powered on within the organization virtual datacenter. The following formulas can be used to calculate resource pools reservations as virtual machines are deployed.

Using the example values, when a virtual machine with 1 vCPU and 2GB of memory is powered on, the corresponding resource pool is updated based on the values defined at the organization virtual datacenter. In this example, the resource pool is dynamically set with the following values:

When an additional virtual machine with the same configuration is powered on, the resource pool is again updated. In this example, the resource pool is set to the following configuration:

This corresponds to 2 vCPUs at 2GHz and 4GB of memory with a 75% guarantee.

As additional virtual machines are deployed, the resource pool is dynamically updated until 100 vCPUs (100GHz) or 100GB of memory is allocated. After the CPU or memory allocation is reached, vCloud Director prohibits powering on additional virtual machines.

In vCloud Director 5.1.1, the CPU limit applied to the resource pool is set to the same value as the allocation of the virtual datacenter. This allows an organization virtual datacenter that has only a single virtual machine to consume as much as possible. In this case, it would be limited to the core speed of the physical CPU, as a 100GHz physical core currently is not available. As additional virtual machines are powered on, only the reservation changes on the resource pool. The limit remains equal to the virtual datacenter allocation. After the allocation is reached, vCloud Director prevents new virtual machines from powering on.

The Pay As You Go model provides the illusion of an unlimited resource pool. This model maps to a sub-resource pool with no configured reservations or limits. Resources are committed only when vApps are deployed in the organization virtual datacenter.

When an organization virtual datacenter is created, vCenter Server creates child resource pools with corresponding resource reservations and limits under the resource pool representing the organization virtual datacenter.

For each vCloud tenant, review the applicable service definition to determine the number and types of organization virtual datacenters to create. Consider expected use cases, workload types, future capacity, and the maximum number of virtual machines per organization virtual datacenter.

Use prescriptive naming for organization virtual datacenters to guide expected user behavior. All users in an organization can view all allocated organization virtual datacenters.

A single provider virtual datacenter mapped to the cluster level can be configured with multiple allocation models for consumers based on their functional requirements. Creating a provider virtual datacenter model (Pay As You Go) does not guarantee that the same settings are applied across the organization virtual datacenter. The model changes the vSphere resource distribution in a similar manner to using multiple allocation models.