Yellow Bricks

by Duncan Epping

vcloud director

vCD Allocation Models – the vCD 1.5 update

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My post on vCloud Director Allocations Models back in September 2010 has always done fairly well in terms of view/visits. Lately I have been receiving some offline questions about how valid this article still is with vCloud Director 1.5 so I decided to go through the same exercise here. Instead of doing a full copy I will just copy and paste the characteristics section for each of the three different Allocation Models. For those who can’t be bothered the short summary is, nothing has changed… I only discovered something which I did not notice the first time around.

Allocation Pool

No changes have been introduced with vCloud Director 1.5 compared to 1.0 for the “Allocation Pool” allocation model. Below are the characteristics of this allocation model and the resource pool / vm construct used on the vSphere layer:

  • Pool of resources of which a percentage will be guaranteed
    • A reservation will be set to guarantee resources on a resource pool level
    • By default the resource pool reservations on CPU is 0% and memory 100%
    • Tenant has a guaranteed set of resources and has the ability to burst to the upper limit
    • The resource pool is not expandable!
  • VM Level characteristics
    • No reservations or limits set on a per VM level for CPU
    • Reservations set on a per VM level for memory. This reservation is based on the percentage of guaranteed resources.

Pay-As-You-Go

Nothing has changed for Pay-As-You-Go either. I slightly changed the wording though to make it more obvious what happens on a vSphere layer:

  • Percentage of resources guaranteed on a per VM level
    • A reservation and a limit will be set on a VM level
    • By default the VM reservation on CPU is 0% and memory 100%
    • By default the vCPU speed is set to 0.26GHz, which means you vCPU will be limited to 0.26GHz
  • The Org vDC resource pool is just an accumulation of all reservations set on a per VM level
    • Note that this will include the memory overhead per VM!
    • The resource pool is set to expandable

Reservation Pool

When looking at the vSphere layer it appears that not much has changed. The characteristics are still the same from a Resource Pool and virtual machine perspective… However I spotted something which was apparently already part of vCoud Director 1.0 but somehow I missed this. vCloud Director 1.x offers you the capability to add a reservation for CPU and memory and even allows you customize the shares! None of the other allocation models allow you to do this!

  • Fully guaranteed pool of resources
    • A reservation will be set to guarantee resources on a resource pool level
    • A limit will be set equal to the reservation
  • No reservations or limits set on a per VM level for CPU
    • Note that is is possible to set a reservation/limit for CPU or Memory with vCloud Director 1.x on a per VM level. See screenshot below, this is configurable on a per virtual machine basis!

 

New session added for PEX

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A couple of weeks back I posted my session details for PEX. I just had a session added to my schedule which I wanted to inform you about. This session was originally hosted by no one less than Mike DiPetrillo. Chris Colotti and I have been asked to take over the session.

Session 1262 (Wednesday 2/12 @ 12:30pm): DR of the Cloud and to the Cloud

This session will look at DR and the cloud. Two different DR scenarios will be presented in depth – DR of the cloud and DR to the cloud. DR to the cloud is how end consumers fail over resources to a cloud provider. DR of the cloud is how you fail over cloud resources from one site to another. This session will go in depth on the consumer and provider side of the architecture. We’ll look at how to replicate the data, what applications are primary targets, how to size environments, how to maintain multi-tenancy, and what to avoid when architecting these solutions. This session is a must for anyone considering tier 1 applications for the cloud.

Presenters: Chris Colotti and Duncan Epping

Don’t forget to add it to your schedule, it is going to be a really cool session!

Doing a vCloud Director Proof of Concept?

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I think this will make you happy. VMware just released the vCloud Director virtual appliance. That means no more installing Red Hat, Oracle and vCloud Director. Just download the appliance and deploy it. On top of there is a great vCloud Cloud Director Evaluators Guide which will help you to evaluate the product.

If you haven’t done anything with vCloud Director before the following articles might also be worth reading, note that these are 1.0 based articles but most of the content is still valid today.

Binding a vCloud Director Provider vDC to an ESX Host?

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One of our partners was playing around with vCloud Director and noticed that they could create a Provider vDC and link it directly to an ESX Host. vCloud Director did not complain about it so they figured it would be okay. However it is a requirement for vCloud Director to have DRS. One of the reasons for this being is the fact that vCloud Director leverages resource pools to ensure tenants receive what they are entitled to.

But back to the issue, they created the Provider vDC and went on to create an Org vDC and even that worked fine… Next stop was the “Organization Network. In order to create one you will need to select a network pool at some point and for some weird reason that didn’t work. After some initial emailing back and forth I noticed they didn’t select a cluster or resource pool but an ESX host. After creating a new Provider vDC based on a vSphere Resource Pool all of a sudden everything started working. Although I cannot really say why it is exactly this part that causes an issue, I can tell you that DRS is a hard requirement and not just  a suggestion!

Did you know? vCloud Director Reservation Pool allocation model fact

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I did not know about this, but someone pointed this out last week and I figured it was worth blogging about as this feature can potentially impact your design. (Think HA admission control policies and resource management)

When you create a VM in an Org vDC which is defined as a Reservation Pool you can actually manually set the shares per type of resource (memory and CPU) and also set a reservation and even a limit if and when needed. Pretty cool, but as you can imagine also very complex at some point to figure out to what it should be set.