This will be the last (third) article in the blog series about how the different vCloud Director (vCD), version 5.1.2, Organization virtual datacenter (Org VDC) allocation models affects the vSphere layer including the vSphere cluster resource pool backing the Org vDC and the virtual machines (VMs). The first blog post in the series covering the Pay As You Go allocation model and can be found here and the second blog post in the series covering the Allocation Pool allocation model can be found here.

This blog post is dedicated to the Org vDC allocation model Reservation Pool.
For the purpose of this blog post i created an Org vDC using the allocation model Reservation Pool with the following settings:

• CPU allocation = 4 GHz
• Memory allocation = 4 GB

The vSphere cluster resource pool, RP-01 (b0106fe9-f341-4dfb-899a-4d2557939d44), created when the Org vDC was created gets the following settings.

The Org vDC CPU allocation configuration applies to the vSphere cluster resource pool:

• CPU Reservation
• CPU Limit

The Org vDC Memory allocation configuration applies to the vSphere cluster resource pool:

• Memory Reservation (1 GB RAM = 1024 MB)
• Memory Limit (1 GB RAM = 1024 MB)

The Reservation type Expandable is not activated for either CPU or Memory.

I created a vApp including 1 VM with 1 vCPU and 1024 MB RAM. Let’s take a look at a vApp VM settings using the vCD UI. The Reservation pool is the only allocation model that makes it possible to manage the below vApp VM settings through the vCD UI:

• CPU Priority (Shares)
• CPU Reservation
• CPU Limit
• Memory Priority (Shares)
• Memory Reservation
• Memory Limit

The only time the there is a change at the vSphere cluster resource pool level is when you reconfigure the Org vDC allocation settings.

When powering on or off a vApp or a vApp VM you’ll see some changes to the Org vDC Allocation. In the picture below we can see that my powered on vApp VM adds a value to the Org vDC Memory reservation used. The value reflects the VM memory overhead. The Org vDC CPU reservation used is still at 0.00 GHz since we have not applied any CPU reservations to the vApp VM.

After adding a CPU reservation, 1000 MHz, and Memory reservation, 1024 MB, to the vApp VM, according to the first picture below, the Org vDC CPU reservation and memory reservation configuration is applied according to the second picture below.

vApp VM Resource Allocation configuration:

Org vDC Allocation CPU reservation used and Memory reservation used.

The Memory reservation used reflects the vApp VM Memory Reservation and the vApp VM overhead.

Summary

• The Org vDC CPU reservation is immediately, upon creation of the Org vDC, applied to the vSphere cluster resource pool configuration options:
  • CPU Reservation
  • CPU Limit
• The Org vDC Memory reservation is immediately, upon creation of the Org vDC, applied to the vSphere cluster resource pool configuration options:
  • Memory Reservation
  • Memory Limit
• There is no change to the vSphere cluster resource pool unless you change the Org vDC CPU allocation and/or Memory reservation.

• The Reservation Pool allocation model is the only one where you can manage the below vApp VM configuration options via the vCD UI:
  • CPU Priority (Shares)
  • CPU Reservation
  • CPU Limit
  • Memory Priority (Shares)
  • Memory Reservation
  • Memory Limit

• Org vDC Maximum number of VMs controls how many VMs the Org vDC can power on unless the CPU and or Memory reservation used value exceeds the CPU and or Memory allocation which then becomes the limit.