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Allocation Models for Organizations using vCloud Director (1026290)

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This article provides information about vCloud Director Allocation Models.


Allocation Models

Allocation Models define the way resources are allocated from the Provider Virtual Data Center (vDC) to a vCloud Director Organization’s vDC. They also define the way resources can be used when deploying vApps within the vCloud Director Organization’s vDC.

Current Allocation Models are:
  • Allocation Pool
  • Reservation Pool
  • Pay-As-You-Go 
Allocation Pool Model
With the Allocation Pool Model:
  • You pay for a pre-allocation of resources. 
  • Organizations are charged for the capacity allocated to their vDCs.
  • You can expand/contract your resources at any time, but only through Service Provider.
  • Lowering the guarantee of resources allows for more vApps to fit into the pre-allocation, but this may impact the ability for the vApp to get the resources it asks for.
  • Service Provider controls resource over-commit by setting a % guaranteed commitment of the Allocation for any vApps deployed (that is, vApp gets an Allocation which is a % guarantee of the reservation). vApps can compete for resources above this guaranteed reservation.
This model:
  • Does not have Resource Quality Of Service (QOS) in this model, which means that over-commitment is possible.
  • Has predictable end of month billing.

Reservation Pool Model

The Reservation Pool Model is useful if you know your applications well enough to optimize your own provisioning. This model has Full Resource Management Controls (reservations, limits, shares) available.
As with the Allocation Pool method, Organizations using the Reservation Pool model are charged for vDC capacity.
With this model, Service Provider cannot over-commit resources. This model guarantees 100% commitment of the vDC Allocation.
Note: With this model, the Service Provider has no Percentage of Resource Guaranteed control.
Pay-As-You-Go Method
With this method (also referred to as the Allocation vApp Model) , you are charged for each vApp virtual machine that is running. Like the Allocation Pool Model, the over-commit is controlled by Service Provider and the Percentage of Resource Guaranteed control is available but the Service Provider can set this to unlimited (Expandable Reservation).
This model facilitates an unlimited option similar to Expandable Reservations – it can use Reservations from the pVDC. 

Allocation of Storage

Storage Allocation is the same for every Resource Allocation Model.
Consider these points:
  • The Service Provider can set a limit on the Storage Allocated.
  • Thin Provisioning is supported for VMFS3.
  • With Thin Provisioning, storage is not pre-reserved.
  • The vCloud Director Administrator can enable/disable Thin Provisioning at the Organization vDC level.
  • Red and Yellow thresholds can be set in the Datastore properties.
  • Cloud Director Admins gets email alert when Yellow threshold hit.
  • No further vApp virtual machines are placed on Datastores at the Red threshold.
Mixing Allocation Models

Carefully plan how Allocation Models are placed in Provider vDCs. Since both the Allocation Pool and Reservation Pool models commit a specific amount of resources (reservations) in Provider vDC, you can easily take resources away from an existing Pay-As-You-Go vDC that shares that Provider vDC. It may be best to use a separate Provider vDC for a Pay-As-You-Go vDC.


vcloud-director  vcloud-director-allocation-models

Update History

12/09/2011 - Added 1.5 to product versions.

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