VCDX Sample Architecture Design Decisions

In preparing for my recent VCDX Defense, I read a great deal of articles and a few books to better understand how to properly document and justify the design decisions I was making. One book in particular provided valuable insight that has helped me not just with the VCDX certification, but also in becoming a better Infrastructure Architect.

In this blog post, I will cover the approach taken when preparing my VCDX documentation with regards to providing insight and justifications for the design decisions made within my VMware Integrated OpenStack architecture.

In preparing for my recent VCDX Defense, I read a great deal of articles and a few books to better understand how to properly document and justify the design decisions I was making. One book in particular provided valuable insight that has helped me not just with the VCDX certification, but also in becoming a better Infrastructure Architect.

In IT Architect: Foundation in the Art of Infrastructure Design (Amazon link), the authors state:

“Design Decisions will support the project requirements directly or indirectly…When a specific technology is required to meet a design goal, justification is important and should be provided. With each design decision there is a direct, intended impact, but there are also other areas that may be affected…These options and their respective value can add quality to the design you make and provide insight into why you took a specific path.”

As I thought through the impact of each design decision, I tried to identify several key points, including:

  • Justification
  • Impact
  • Decision Risks
  • Risk Mitigation
  • Requirements Achieved

After I had identified each of those key points, and in some cases multiple points, for each category I made sure they were properly documented. The book provided an example table to draw inspiration from, in addition Derek Seaman did as well on a blog article. I modified the examples to fit my writing style and then included a specific table for each design decision made at the end of each major section or heading within my architecture documentation.

An example of the table and categories showing the reasoning behind a set of design decisions from my VMware Integrated OpenStack VCDX Architecture document:

vcdx_design_decision_sample

Now, when I need to revisit a design decision or another architect is reviewing the decisions within the design, there is additional information to provide insight into the thought process. It also helps to highlight what impact the decision has on the architecture as a whole.

Beyond the table and the relevant information for the design decision, it may be necessary to highlight the alternatives that were considered. As we know, there are usually multiple ways to meet a requirement — “showing your work” and being able to explain why you chose to do X versus Y in the VCDX Defense is an important aspect of the process. I found doing so within my documentation useful and you may find that to be true also.

Enjoy!

The opinions expressed in this article are entirely my own and based solely on my own VCDX certification experience. They may or may not reflect the opinions of other VCDX certification holders or the VMware VCDX program itself.


Arrasjid, John Y., Mark Gabryjelski, and Chris McCain. “Chapter 2, Design Decisions.” IT Architect: Foundation in the Art of Infrastructure Design; a Practical Guide for IT Architects. Upper Saddle River, NJ: IT Architect Resource, 2016. 49. Print.

VCDX Sample Architecture Table of Contents

During the process of writing the documentation necessary for the VCDX certification, I read several books and a fair number of blog articles. One article in particular that I found helpful was from Derek Seaman’s blog.

In the spirit of paying it forward, I am going to share my own table of contents for others to use as a starting point. No two will be the same and some of the things I included may not be necessary in your own design — you may even feel there are sections that are missing from my own. If nothing else, I hope it can be a starting point for you in the journey towards earning the VCDX certification.

During the process of writing the documentation necessary for the VCDX certification, I read several books and a fair number of blog articles. One article in particular that I found helpful was from Derek Seaman’s blog.

Sample VCDX-DCV Architecture Outline

In the spirit of paying it forward, I am going to share my own table of contents for others to use as a starting point. No two will be the same and some of the things I included may not be necessary in your own design — you may even feel there are sections that are missing from my own. If nothing else, I hope it can be a starting point for you in the journey towards earning the VCDX certification.

Enjoy!

The opinions expressed in this article are entirely my own and based solely on my own VCDX certification experience. They may or may not reflect the opinions of other VCDX certification holders or the VMware VCDX program itself.

Post-Defense VCDX Thoughts

“Nothing in the world is worth having or worth doing unless it means effort, pain, difficulty… I have never in my life envied a human being who led an easy life. I have envied a great many people who led difficult lives and led them well.” -Theodore Roosevelt

That quote from Theodore Roosevelt sums up rather well the VCDX certification. The VCDX certification takes a great deal of effort, pain and difficulty to accomplish. My personal journey included multiple defense attempts — much to my dismay and benefit. Fortunately, it was all worth it!

I am VCDX #257!

The VCDX certification requires a significant amount of time to earn. If I had to estimate it, I would say I spent between 200+ hours working on my design documentation, defense presentation, mock defenses, Q&A sessions and just general research. The submitted design was also an actual work project, so some of that time investment was for my job — an added benefit not all candidates have.

The one lesson I would share with others thinking about or pursuing their own VCDX certification is the following — be careful who you ask advice of or take advice from. If they have not been a panelist in the past, their view into what to do (or not to do) is going to be mostly opinion. The VCDX program held a Q&A call the Friday before the defenses began in May.

On the call were Joe Silvagi, Simon Long and Karl Childs — all three are heavily involved in the program. The most frequent questions asked by the candidates started with the phrase, “My mentor says” or “The community says”. In nearly every instance the response from Joe was along of the lines of that isn’t right.

Attend one (or more) VCDX workshops prior to submitting so that you can ask questions and reach out to the people running the workshops to get trustworthy responses.

That’s all the advice I have to give.

There is an African Proverb, and the quote is outside one of the VMware conference rooms, that says:

“If you want to go fast, go alone. If you want to go far, go together.”

This is true of the VCDX certification. I got to this point not because I went alone, but because I went with others.

My wife – No one on this earth has supported me more. The countless hours over the past two decades of late nights as I strived to advance my career. This is as much her certification as it is my own.

Rich Steck (Adobe) – He mentored me during one of the most difficult years in my career. He challenged me to figure out where I wanted to go and to find paths to get there. Most importantly, he listened.

Frans van Rooyen (Adobe) – Already a brilliant cloud architect in his own right, he mentored me in my role as a Compute Platform Engineer for two years. He let me constantly challenge all of the decisions we were making (on-the-fly) as we built a rather large private cloud across the globe. He introduced me to VMware technologies and helped me gain the skills I would need to land my dream job at VMware in two short years.

Andrew Nelson (VMware) – While at Adobe, Frans introduced me to Andrew. Andy and I spoke at VMworld together in San Francisco and Barcelona in 2014. We briefly worked on a book together, during which time he told me if I wanted to get a job at VMware, I’d be surprised how quickly it would happen. I had an offer for my current role barely 1 month later.

OneCloud Architecture Team (VMware) – My dream job came with the opportunity to work with 3 double-VCDX certification holders. The first architecture review board call I attended they tore into another architect over his vRA design and it was at that moment I knew I was going to have to step up my game significantly to play with them. What a blessing it has been to work with them for the past two years — each of them has helped me grow my skills as an architect immensely. They taught me to critically challenge a design decision, not just for the sake of arguing, but because we are trying to understand the rationale for the decision.

Their support continued from afar as I went through the process of submitting and defending my design for my own certification. When I got the email saying I was now VCDX #257, they were right there celebrating my success with me.

Thank you to each of you for helping me realize my dreams and earn the VCDX certification!

 

Install VMware Integrated OpenStack on VCF

I am currently pursuing my VCDX certification and the design I have submitted is based on VMware Cloud Foundation and VMware Integrated OpenStack. As part of the required documentation, I included a deployment guide — unfortunately, it is not as simple as laying down the SDDC components and the VIO vApp for the deployment.

This blog post will cover a couple items that are needed to get the two pieces playing together.


Shared Edge & Workload Cluster

The VCF architecture currently has a limitation that a vCenter Server can only have a single vSphere cluster — it’s a 1:1 relationship. VMware Integrated OpenStack requires either 3 clusters in a single vCenter Server or a management cluster in one vCenter Server instance and two clusters in a second vCenter Server. Neither of these options are compatible with VMware Integrated OpenStack.

In order to make it work, we are going to use a two vCenter Server deployment of VMware Integrated OpenStack and modify the OMS server to combine the NSX Edge and Workload Clusters into one. We do this by editing a single configuration file and restarting the oms service running on the VIO vApp Management (OMS) VM.

$ cd /opt/vmware/vio/etc
$ sudo vim moms.properties

Add the following line to the end of the file:
oms.allow_shared_edge_cluster = true

$ sudo restart oms

VMware Integrated OpenStack can now be deployed on top of VMware Cloud Foundation.


VXLAN-backed External Network

This one is a bit trickier and is an obstacle whether or not you are using VMware Cloud Foundation as the infrastructure layer.

Logically, the end result for the OpenStack external network is to attach to a VXLAN port group created by NSX. The NSX logical switch network is attached to the internal interface on a NSX Distributed Logical Router.

The following is the logical diagram for the architecture.

external openstack

The issue is that during the deployment of an OpenStack instance using VMware Integrated OpenStack, you have to specify an external network. However, VMware Integrated OpenStack will not allow a vSphere Administrator to select a VXLAN port group during the deployment. I got around this by creating a non-VXLAN port group on the DVS used only for the deployment.

Once the OpenStack deployment is complete, I needed to attach the actual VXLAN-backed port group as the external network.

SSH to the OMS server
$ ssh -l viouser oms.domain.local

SSH to an OpenStack controller VM
$ ssh controller01
$ sudo cp /root/cloudadmin_v3.rc .
$ source cloudadmin_v3.rc
$ neutron

(neutron) net-list
(neutron) net-create --provider:network_type=portgroup --provider:physical_network=virtualwire-XX vio-external-network
(neutron) net-list

The network will now appear in the OpenStack network list. Go ahead and create your subnet for the external IP addresses, based on the network assignment in your environment.

If you have questions or issues with implementing these changes in your environment, please reach out.

Using the VMware Validated Design Reference Material

Caution, this post is highly opinionated.

I am deep into the process of completing my VCDX design documentation and application for (hopefully) a Q2 2017 defense. As it so happens, a short conversation was had on Twitter today regarding a post on the VMware Communities site for the VMware Validation Design for SDDC 3.x, including a new design decision checklist.

twitter-screen

The latest version of the VMware Validated Design (VVD) is a pretty awesome product for customers to reference when starting out on their private cloud journey. That being said, it is by no means a VCDX design or a set of materials that could simply be re-purposed for a VCDX design.

Why? Because there are no customer requirements.

For the same reason a hypothetical (or fake) design is often discouraged by people in the VCDX community, the VVD suffers from the same issue. In a vacuum you can make any decision you want, because there are no ramifications from your design decision. In the real-world this is simply not the case.

Taking a look at the Design Decisions Checklist, it goes through the over 200 design decisions the VVD made in the course of developing the reference architecture. The checklist does a good job of laying out the fields the design decision covers, like:

  • Design Decision
  • Design Justification
  • Design Implication

Good material. But if you’ve read my other post on design decisions, which you may or may not agree with, it highlights that a decision justification is made based on a requirement.

Let’s take a look at just one of the design decisions made by the VVD product and highlighted in the checklist.

vvd_decision_screencap

The decision is to limit a single compute pod to a single physical rack, as in no cross-rack clusters. Sounds like a reasonable decision, especially if the environment had a restriction on L2 boundaries or some other requirement. But what if I have a customer requirement that said a compute node must be able to join any compute pod (cluster) regardless of physical rack location within a data center?

Should I ignore that requirement because the VVD says to do otherwise?

Of course not.

My issue with the Twitter conversation is two-fold:

  1. The VVD design decisions are not in fact design decisions, but design recommendations. They can be used to help a company, group or architect to determine, based on their requirements, which of these “decisions” should be leveraged within their environment. They are not die-hard decisions that must be adhered to.
  2. From a VCDX perspective, blindly assuming you could copy/paste any of these design decisions and use them in a VCDX defense is naive. You must have a justification for every design decision made and it has to map back to a customer requirement, risk or constraint.

I also do not think that is what  was saying when he initially responded to the Tweet about the checklist. I do think though that some people may actually think they can just take the VVD, wrap it in a bow and call it good.

My suggestion is to take the VVD design documentation and consider it reference material, just like the many other great books and online resources available to the community. It won’t work for everyone, because every design has different requirements, constraints and risks. Take the bits that work for you and expand upon them. Most importantly, understand why you are using or making that design decision.

Let me know what you think on Twitter.

Again, this post is highly opinionated from my own limited perspective. Do not mistake it for the opinion of VMware or any VCDX certified individuals.