My VCAP5-CIA Experience

Yesterday (21st July 2014) I sat and passed the VMware Certified Advanced Professional Cloud Infrastructure Administration (VCAP5-CIA) exam at my local test centre here in Melbourne, Australia.

As with the VCAP-DCA which I did as a prerequisite for VCDX back in 2011, the CIA exam is a live lab exam where VMware get you to demonstrate your hands on expertise with their products.

I find the value of the VCDX, is in part due to the fact it is a requirement to have not only “Design” but hand-on implementation/administration/troubleshooting experience as it is my opinion a person should not be an architect unless that person has the hands on experience and ability to implement and support the solution as designed.

So, enough rambling, what did I think of the VCAP-CIA?

As with all VMware certifications, the exams are generally well written and closely aligned to the blueprints which VMware provide. For VCAP-CIA the blueprint and exam registration can be found here.

The VCAP-CIA was no different, and aligned very well to the blueprint.

The exam is 210 minutes and has 32 questions some of which are simple 1 min tasks where others require a significant amount of work. One secret to all VCAP exams is you are challenged not only by the questions, but by the clock as time is the enemy. This makes time management essential. Do not get caught up of one question, if your unsure, do your best and move on.

Be ware some questions are dependant on successfully completion of earlier questions, but in saying that, a lot of questions are not, so don’t be afraid to skip questions if your struggling as you will still be able to complete many other questions.

The actual live lab in the exam consists of seven ESXi hosts, three vCenter Server virtual machine, four VMware vCloud™ Director (vCD) cells plus additional supporting resources. The lab has a number of pre-configured vApps and virtual machines will also be present for use with certain tasks. It is importaint to understand the lab environment is based on VMware vCloud Suite 5.1 and vCenter Chargeback Manager 2.5, not vCloud 5.5 so ensure you study and prepare using the correct versions of vCloud/vCB!

At this stage some of you may be thinking, I just breached the NDA telling the world about the exam? Well I haven’t and this is the beauty of how VMware does their exam blueprints, the above information is all available in the blueprint so there is not trickery or secrecy to the lab.

As for the questions in the VCAP-CIA, you will not get a brain dump out of me, but what I can tell you is the questions are in most cases very clear and what is asked of the candidates is vastly skills that anyone with any significant vCD experience would be familiar with. For example, the blueprint under Objection 1.2 – Configure vCloud Director for scalability, states under skills and abilities:

 Generate vCloud Director response files
 Add vCloud cells to an existing installation using response files
 Set up vCloud Director transfer storage space
 Configure vCloud Director load balancing

Its safe to say if you know the blueprint properly, you will be able to complete the tasks in the exam, and as a result, get a passing score.

Now the bad news!

Being based in Melbourne, Australia, and the live lab is being accessed by RDP to a location in Seattle, USA. So what does this mean, Latency!

I was only able to complete about 2/3rd’s of the questions in large part due to the delay in the screen refreshing after switching between for example the vCD web interface and production documentation, Putty etc.

On that point, all the PDF and HTML documentation is available in the exam, but I would highly recommend you don’t rely on it, because accessing the doco and searching/scrolling for things is very slow, at least it was for me.

I had numerous occasions where the screen would totally freeze which was a concern, but I soon accepted this was a latency issue, and the lab was fine, and waited out the freezes (which varied from a few seconds to around 20 seconds, which feels like hours when your against the clock!)

I have heard from numerous other VCAP-CIA who sat the exam in the Australia/NZ region that they experienced the same issues, so if you are A/NZ based, or any location a long way from the USA, be prepared for this.

Now being a live lab, the exam is not scored on the spot, and you have to wait for VMware to score the exam and then you will receive an electronic score report via email. The exam receipt says 15 business days, but I was very impressed that less than 24 hours after sitting the exam, I got my score report. Obviously VMware education have done a great job in automating the scoring process, which is a credit to them!

Overall, the experience of the VCAP-CIA was very good, the exam/questions are a solid test of vCloud related skills and experience, so great work VMware Education!

I am very pleased to have completed this exam and all prerequisites for VCDX-Cloud (VCP-Cloud, VCAP-CID and VCAP-CIA) and I will be submitting my application in the near future.

Enterprise Architecture & Avoiding tunnel vision.

Recently I have read a number of articles and had several conversations with architects and engineers across various specialities in the industry and I’m finding there is a growing trend of SMEs (Subject Matter Experts) having tunnel vision when it comes to architecting solutions for their customers.

What I mean by “Tunnel Vision” is that the architect only looks at what is right in front of him/her (e.g.: The current task/project) , and does not consider the implications of how the decisions being made for this task may impact the wider I.T infrastructure and customer from a commercial / operational perspective.

In my previous role I saw this all to often, and it was frustrating to know the solutions being designed and delivered to the customers were in some cases quite well designed when considered in isolation, but when taking into account the “Big Picture” (or what I would describe as the customers overall requirements) the solutions were adding unnecessary complexity, adding risk and increasing costs, when new solutions should be doing the exact opposite.

Lets start with an example;

Customer “ACME” need an enterprise messaging solution and have chosen Microsoft Exchange 2013 and have a requirement that there be no single points of failure in the environment.

Customer engages an Exchange SME who looks at the requirements for Exchange, he then points to a vendor best practice or reference architecture document and says “We’ll deploy Exchange on physical hardware, with JBOD & no shared storage and use Exchange Database Availability Groups for HA.”

The SME then attempts to justify his recommendation with “because its Microsoft’s Best practice” which most people still seem to blindly accept, but this is a story for another post.

In fairness to the SME, in isolation the decision/recommendation meets the customers messaging requirements, so what’s the problem?

If the customers had no existing I.T and the messaging system was going to be the only I.T infrastructure and they had no plans to run any other workloads, I would say the solution proposed could be a excellent solution, but how many customers only run messaging? In my experience, none.

So lets consider the customer has an existing Virtual environment, running Test/Dev, Production and Business Critical applications and adheres to a “Virtual First” policy.

The customer has already invested in virtualization & some form of shared storage (SAN/NAS/Web Scale) and has operational procedures and expertises in supporting and maintaining this environment.

If we were to add a new “silo” of physical servers, there are many disadvantages to the customer including but not limited too;

1. Additional operational documentation for new Physical environment.

2. New Backup & Disaster Recovery strategy / documentation.

3. Additional complexity managing / supporting a new Silo of infrastructure.

4. Reduced flexibility / scalability with physical servers vs virtual machines.

5. Increased downtime and/or impact in the event hardware failures.

6. Increased CAPEX due to having to size for future requirements due to scaling challenges with physical servers.

So what am I getting at?

The cost of deploying the MS Exchange solution on physical hardware could potentially be cheaper (CAPEX) Day 1 than virtualizing the new workload on the existing infrastructure (which likely needs to be scaled e.g.: Disk Shelves / Nodes) BUT would likely result overall higher TCO (Total Cost of Ownership) due to increased complexity & operational costs due to the creation of a new silo of resources.

Both a physical or virtual solution would likely meet/exceed the customers basic requirement to serve MS Exchange, but may have vastly different results in terms of the big picture.

Another example would be a customer has a legacy SAN which needs to be replaced and is causing issues for a large portion of the customers workloads, but the project being proposed is only to address the new Enterprise messaging requirements. In my opinion a good architect should consider the big picture and try to identify where projects can be combined (or a projects scope increased) to ensure a more cost effective yet better overall result for the customer.

If the architect only looked at Exchange and went Physical Servers w/ JBOD, there is zero chance of improvement for the rest of the infrastructure and the physical equipment for Exchange would likely be oversized and underutilized.

It will in many cases be much more economical to combine two or more projects, to enable the purchase of a new technology or infrastructure components and consolidate the workloads onto shared infrastructure rather than building two or more silo’s which add complexity to the environment, and will likely result in underutilized infrastructure and a solution which is inferior to what could have been achieved by combining the projects.

In conclusion, I hope that after reading this article, the next time you or your customers embark on a new project, that you as the Architect, Project Manager, or Engineer consider the big picture and not just the new requirement and ensure your customer/s get the best technical and business outcomes and avoid where possible the use of silos.

Nutanix Tech Notes for VMware vSphere

I thought I would put together a single page which has links to all the current Nutanix Tech Notes relating to VMware vSphere as well as have a bit of a teaser list of upcoming documents.

This will be a living post, and updated regularly as new documents are released.

Tech Notes

1. Nutanix Storage Configuration for VMware vSphere

2. VMware vSphere Networking on Nutanix

3. VMware High Availability Configuration for Nutanix (Coming soon)

4. VMware Distributed Resource Scheduler on Nutanix (Coming soon)

5. VMware Storage configuration on Nutanix (Coming soon)

6. VMware vSphere Cluster design with Nutanix (Coming soon)

7. Optimal Virtual Machine design with Nutanix (Coming soon)

8. Monster VM design with Nutanix (Coming soon)

ESXi Host Isolation Response and custom isolation address configuration.

I was reviewing a vSphere design recently and I came across an interesting design choice which I thought I would share.

The architect selected the isolation response of “Leave Powered On” and disabled  “das.usedefaultisolationaddress”  (which is by default enabled) and configured multiple custom isolation addresses using the “das.isolationadressX” advanced setting.

The architect explained that this was done to minimize the chance of a false positive isolation event. In many environments such as ones using IP storage or where the ESXi Management VMKernel default gateway is not highly available, this can be a very good idea.

In this environment, the storage was provided via FC and the default gateway was highly available.

So was there a benefit in changing the default setting of “das.usedefaultisolationaddress” and configuring custom isolation addresses?

The short answer is No.

This is because the isolation response is configured with “Leave Powered On” so regardless of the host being isolated or not, the Virtual Machines will remain powered on.

So keep it simple, if your isolation response is “Leave Powered On” there is no need to change either of these advanced settings.

The below articles show examples of isolation response and custom isolation addresses configurations for IP Storage, FC storage and Hyper-converged environments.

Related Articles

1. Host Isolation Response for IP Storage
2. Host isolation response for FC based Storage
3. Host Isolation Response for a Nutanix Environment

Example Architectural Decision – Default Virtual Machine Compatibility Configuration

Problem Statement

In a VMware vSphere 5.5 environment, what is the most suitable configuration for Virtual Machine Compatibility setting at the Datacenter and Cluster layers?


1. vSphere Flash Read Cache is not required.
2. VMDKs of greater than 2TB minus 512b are not required.


1. Reduce complexity where possible.
2. Maximize supportability.

Architectural Decision

Configure the vSphere Datacenter level “Default VM Compatibility” as “ESXi 5.1 or later” and leave the vSphere Cluster level ”Default VM Compatibility” as “Use datacenter setting and host version” (default).


1. Avoid limiting management of the environment to the vSphere Web Client.
2. The Default VM Compatibility only needs to be set once at the datacenter layer and then all clusters within the datacenter will inherit the desired setting.
3. Reduce the dependency of the Web Client in the event of a disaster recovery.
4. As vFRC and >2TB VMDKs and vGPU are not required, there is no significant advantage to HW Version 10.
5. Ensuring a standard virtual machine compatibility level is maintained throughout the environment and reducing the chance of mismatched VM version types in the environment.
6. Simplicity.


1. Virtual Machine Hardware Compatibility automatic update must be DISABLED to prevent the VM hardware being automatically upgraded following a shutdown.
2. vSphere Flash Read Cache (vFRC) cannot be used.
3. VMDKs will remain limited at 2TB minus 512b.


1. Virtual Machine HW Version 10 (vSphere 5.5 onwards).
2. Virtual Machine HW Version 8 (vSphere 5.0 onwards).
3. Virtual Machine HW Version 7 (vSphere 4.1 onwards).
4. Older Virtual machine HW versions.


Virtual Machine Swap File Location & Capacity Usage on Nutanix

The Location of the Virtual Machine swap file can be critical when deploying vSphere with traditional centralized storage solutions, or legacy solutions which acknowledge “zeros” or “White-space” as the Virtual Machine swap file can be as large as the VMs configured vRAM where Memory Reservations are not used.

The below shows the default configuration.

If a VM resides on Tier 1 storage for example, and the VM does not have a memory reservation set (or a reservation of less than 100%), the Swap-file will take up valuable Tier 1 storage capacity.

This can be avoided by specifying a Swap-file datastore however this introduces complexity and in the event the Swap-file datastore is on a low tier of storage, performance in the event of swapping will degrade significantly.

Some platforms recommend having different datastores for VM swap files to minimize the overheads on de duplication or replication for environments using SRM as discussed in Example Architectural Decision – Virtual Machine Swap-file location for SRM Protected VMs.

The Nutanix Distributed File System does not write “White space” to disk, as a result the impact of Virtual Machine swap files is negligible which makes the issue of swap file placement much less of an issue.

The only time when Virtual machine swap files will use storage capacity in the Nutanix Distributed File System is when host memory utilization is >100% and swapping needs to occur.

As such, the default vSphere configuration of “Virtual Machine Directory” is ideal for Nutanix environments and valuable storage capacity is not unnecessarily wasted resulting in increased usable space, reduced complexity by removing the requirement for dedicated swap-file datastores without compromising the benefits of de-duplication and compression.

VCDX Defence Essentials – Part 3 – Preparing for the Troubleshooting Scenario

Following on from Part 1 - Preparing for the Design Defence & Part 2 - Preparing for the Design Scenario, Part 3 covers my tips for the final stage of the VCDX defence, the Troubleshooting Scenario.

After completing the 75min Design defence and the 30min Design Scenario, if your still standing and haven’t retreated at full speed, your final challenge is the 15min Troubleshooting Scenario.

As mentioned in the previous Parts of this series, I am not a official panellist and I do not know how the scoring works. The below is my advice based on conducting mock panels, the success rate of candidates I have conducted mock panels with and my successfully achieving VCDX on the 1st attempt.

If you have read Part 2, then you should notice several similarities in both the common mistakes and tips below.

Common Mistakes

1. Trying to guess the solution to the issue

Taking pot shot guesses at what the problem/s might be does not prove your expertise. If you don’t methodically work through the issue and just keep making guesses, your not doing yourself or the people trying to assess your expertise any good.

2. Not documenting the troubleshooting steps you have completed

Assuming you have not made Mistake #1, and you are methodically working through the troubleshooting scenario, a common mistake I see is a candidate getting confused about what they have or have not investigated.

When candidates repeat the same troubleshooting steps because they have lost track, it does nothing but waste time and does not increase your chance of passing.

15 mins goes by in a flash, you cannot afford to waste time!

3. Going down a rabbit hole

Same as in the design scenario, I have observed many candidates who are clearly very knowledgeable, who have spent the majority of the time troubleshooting one specific area of the environment. eg: Just the vSphere layer

Doing this may demonstrate your expertise in one area really well, but this does not help getting as many potential issues eliminated in the scenario as possible within the time constraint.

4. Being Mute!

Again, same as in the design scenario, I have seen candidates who stand starring at the troubleshooting scenario and the whiteboard for mins at a time.


Tips for the Troubleshooting Scenario

1. Do not try to guess the solution to the issue

If you happen to guess the solution (assuming there is one.. hint hint) what expertise have you demonstrated to the panel for them to score you on? The answer is “bugger all” (This is Australian for “none”).

Talk the panel through your troubleshooting methodology, for example, you might choose to go through OSI models layers, or you may choose to start with, Networking, then move onto Storage, then application, then vSphere etc.

The goal of this section of the defence is to demonstrate your troubleshooting skills, so make sure you explain what your trying to eliminate. eg: If a VM has lost connectivity you may ask the panel to perform a vMotion of VM1 from host A to host B. You could explain to the panel that if the ping begins to work following the vMotion, you plan to investigate the networking of Host A. If the ping does not start working, you will continue to investigate for a larger networking issue, such as a VLAN specific problem.

2. Documenting your troubleshooting steps & findings

Ensure you methodically address each of the key areas of a vSphere solution by writing on the whiteboard headings like the following:

a) Storage/SAN/Protocol

b) Networking/Firewall

c) Compute HW

d) Application/Guest OS

e) vSphere

Ensure you eliminate several (i’d suggest >=3) potential issues in each section, so you are covering off the entire environment and record what you have done & the result of the troubleshooting step.

Keep in mind, you only have 15 mins, so 1 item per min is required if you are to cover all areas off thoroughly.

3. Don’t go down a rabbit hole!

Same as in the design scenario, I have observed many candidates who are clearly very knowledgeable, who have spent the majority of the time troubleshooting one specific area of a vSphere environment. eg: Storage

Doing this may demonstrate your expertise in one area really well, but this does not help getting as many potential issues eliminated in the scenario as possible within the time constraint.

Once you have looked into 3 potential issues in storage, move onto Networking, or vSphere etc.

Do not spend more than 60-90 seconds on any one troubleshooting step as this is preventing you demonstrating broad expertise which is the purpose of VCDX.

4. Think out Loud!

Again, same as in the design scenario, I have seen candidates who stand starring at the troubleshooting scenario and the whiteboard totally silent for mins at a time.

Talk the panel through your thought process and expected outcomes for troubleshooting actions.

I cannot give you advise, if I don’t know what your thinking! Same with the panellists, they can’t score you if you don’t verbalize your thought process.

No matter what, keep thinking out loud, if your working through options in your mind, that’s what the panel want’s to hear, so let them hear it!


I hope the above tips help you prepare for the VCDX design scenario and best of luck with your VCDX journey. For those who are interested, you can read about My VCDX Journey.

If you have any questions on the VCDX process or the advise given in this series please leave your comments and I will compile a list of questions and do a Q&A post.

VCDX Defence Essentials – Part 2 – Preparing for the Design Scenario

Following on from Part 1 - Preparing for the Design Defence, Part 2 covers my tips for the Design Scenario part of the VCDX defence.

After a short break following your 75min Design defence, your neck deep in the Design Scenario. You are presented with a scenario which you need to demonstrate your abilities to gather requirements and while you will not be able to complete a design in 30mins, you should be able to demonstrate the methodology you use to start the process.

As mentioned in Part 1, I am not a official panellist and I do not know how the scoring works. The below is my advice based on conducting mock panels, the success rate of candidates I have conducted mock panels with and my successfully achieving VCDX on the 1st attempt.

Common Mistakes

1. Not gathering and identifying requirements/constraints & risks

The design scenario is very high level, and does not provide you with all the information required to be able to properly start a design. Not identifying and clarifying requirements/constraints and risks will in most cases prevent a candidate from successfully being able to start the design process.

Note: The word “Start” is underlined! You can’t start a design without knowing what your designing for… so don’t make this mistake.

2. Not documenting the requirements/constraints & risks

Assuming you have not made Mistake #1, and you have gathered and clarified the requirements/constraints & risks, the next mistake is not to write them down. I have seen many candidates do an excellent job of gathering the information, to then fall in a heap because they waste time asking the same questions over again because the have forgotten the details.

30 mins is not a long time, you cannot afford to waste time repeating questions.

3. Going down a rabbit hole

I have observed many candidates who are clearly very knowledgeable, who have spent 10-15 mins talking about one topic, such as HA and going into admission control options and pros/cons, isolation response etc. They demonstrated lots of expertise, but this did not help getting as much progress as possible into a design within the time constraint.

The design may be excellent in one key area (eg: HA) but severely lacked in all other areas, which would certainly led to a low score in the design scenario.

4. Not adjusting to changes

The information given to you in the design scenario may not always be correct and may even change half way through the design. Just like in a customer meeting, the customer doesn’t always know the answers to your questions, and may give you an incorrect answer, or simply not know the answer, then later on, realise they gave you incorrect information and correct themselves.

I deliberately throw curve-balls into mock design scenarios and I have observed several times a candidate be say 25 mins into the design scenario and this happens, and they failed to adjust for whatever reason/s.

5. Being Mute!

I have seen candidates who stand starring at the whiteboard, or drawing away madly, while completely mute. Then after 5-10 mins of drawing/thinking candidates then talk about what they came up with.

Do you stand in customer meetings mute? No! (Well, you shouldn’t!)


Tips for the Design Scenario

1. Clarify the Requirements/Constraints

Start by clarifying the information that has been provided to you. The information provided may be contradictory, so get this sorted before going any further.

2. Write the requirements/constraints & risks on the Whiteboard

Once you have clarified a piece of information that has been provided to you, write it on the whiteboard under section heading, such as:

a) Requirements

b) Constraints

c) Risks

d) Assumptions

Now, you can quickly review these items, without having to remember everything and if a curve-ball is thrown at you, you can cross out the incorrect information and write down the correct info and this may assist you modifying your design to cater for the changed requirement/constraint etc.

As you work through the scenario, you may be able to clarify an assumption, so you can remove it as an assumption/risk, this shows your working towards a quality outcome.

3. Write down your decisions!

Ensure you address each of the key areas of a vSphere solution by writing on the whiteboard headings like the following:

a) Storage

b) Networking

c) Compute

d) Availability

e) Datacenter

Ensure you write down at least 3 items per section, so you are covering off the entire environment.

As you make a design choice, write it down, eg: under storage, you may be recommending or constrained to use iSCSI, so write it down. iSCSI / Block storage.

So, aim to have 5 section headings like the above examples, and at  least 3 items per heading by the end of 30 mins. If you do the math, that’s only 6 mins per section, or 2 mins per item so make them count.

eg: Availability does not just mean N+1 vSphere cluster, what about say, environmental items such as UPS? A successful VCDX level design is not just about vSphere.

4. Verbalize your thought process.

I cannot give you advise, if I don’t know what your thinking! Same with the panellists, they can’t score you if you don’t verbalize your thought process.

No matter what, keep thinking out loud, if your working through options in your mind, that’s what the panel want’s to hear, so let them hear it!

If you are mute for a large portion of the 30 mins, the lower the chances you have of increasing your score.

5. Show how you adjust to changes in requirements/constraints/assumptions!

As a VCDX candidate, your most likely an architect day to day, so you would have dealt with this many times in real life, so deal with it in the design scenario!

If your 25 mins into the design scenario, and the panel suddenly tells you the CIO went out drinking on the weekend with his new buddy at storage vendor X and decided to scrap the old vendors storage and go for another vendor, deal with it!

Talk about the implications of moving from vendor X to vendor Y, for example FC to NFS and how this would change the design and would it still meet the requirements or would it be a risk?

6. Don’t be afraid to draw diagrams – but don’t spend all day making it pretty!

Use the whiteboard to draw your solution as it develops, but don’t waste time drawing fancy diagrams. A square box with ESXi written in it, is a Host, it doesn’t need to be pretty.

eg: If your drawing a 16 node cluster, draw three squares, Labelled ESXi01, ESXi…. and ESXi16, don’t draw 16 boxes, this adds no value, wastes time, and makes the diagram harder to draw.



I hope the above tips help you prepare for the VCDX design scenario and best of luck with your VCDX journey. For those who are interested, you can read about My VCDX Journey.

In Part 3, I will go through Preparing for the Troubleshooting Scenario, and how to maximize your 15 mins.

VCDX Defence Essentials – Part 1 – Preparing for the Design Defence

Even before I achieved my VCDX in May 2012, I had been helping VCDX candidates by doing design reviews and more importantly conducting mock panels.

So over the last couple of years I would estimate I would have been involved with at least 15 candidates, which range from a mock panel and advice over a WebEx, to mentoring candidates through their entire journey.

I would estimate I have conducted easily 30+ mock panels, from which I have decided to put together the most common mistakes candidates make, along with my tips for the defence.

Note: I am not a official panellist and I do not know how the scoring works. The below is my advice based on conducting mock panels, the success rate of candidates I have conducted mock panels with and my successfully achieving VCDX on the 1st attempt.

Common Mistakes

1. Using a Fictitious Design

In all cases where I have done a mock panel for a candidate using a Fictitious design, even in cases where I did not know it was fictitious, it becomes very obvious very quickly.

The reason it is obvious for a mock panellist is due to the lack of depth the candidate can go into about the solution, for example, requirements.

In my experience, candidates using fictitious designs generally take multiple attempts before successfully defending.

This may sound harsh, but if you need to use a fictitious design, you probably don’t have enough architecture experience for VCDX, otherwise you would be able to choose from numerous designs to submit, rather than creating a fictitious design.

Some candidates use fictitious designs for privacy or NDA reasons, in this case, I would strongly recommend you should be able to remove customer specific details and defend a real design.

Note: For those VCDXs who have passed with a fictitious design, I am not in any way taking away from there achievement, if anything, they had more of a challenge that people like me who used a real design.

2. Giving an answer of “I was not responsible for that portion of the design”.

If you give this answer, you are demonstrating that you do not have an expert level understanding of the solution as a whole, which translates to Risk/s as the part of the design you were responsible for may not be compatible with the component/s you were not involved in.

A VCDX candidate may not always be the lead architect on a project, but a VCDX level candidate will always ensure he/she has a thorough understanding of the total solution and will ask the right questions of other architects involved with the project to gain at least a solid level of understanding of all parts of the solution.

With this understanding of other components of the total solution, a candidate should be able to discuss in detail how each component influenced other areas of the design, and what impact (positive or negative) this had on the solution.

3. Not knowing your design! 

This is the one which surprises me the most, if your considering submitting for VCDX, or already have submitted and been accepted, you should already know your design back to front, including the areas which you may not have been responsible for.

You should not be dependant on the power point presentation used in your defence as this is really for the benefit of the panellists, not for you to read word for word.

Think about the VCDX panel this way, You (should) know more about your design that the panel does for the simple reason, its your design.

So you have an advantage over the panellists – ensure you maximize this advantage by knowing your design back to front.

If you cannot comfortably talk about your design for 75mins without referring to reference material, you probably should review your design until you can.

4. Not having clear and concise answers of varying depths for the panellists questions

I hear you all saying, how the hell do I know what the panel will ask me? As a VCDX candidate preparing to defend, your basically saying, I am an Expert in virtualization and I want to come and have my expertise validated.

As an Expert (not a Professional or Specialist, but an EXPERT) you should be able to go through your design, and with your reviewers hat on, write down literally 50+ questions that you would ask if you were reviewing this document for somebody else, or indeed, acting as a real or mock panellist.

In my experience, I predicted approx 80% of the questions the panel ended up asking me, which made my defence a much less stressful experience than it may have been otherwise.

Once you have written down these questions (seriously, 50+), you should ask yourself those questions and ensure you have answers to them. The answers you should have, or prepare should be

a) 1st Level – 30 seconds or less which cover the key points at a high level

b) 2nd Level – A further 30 – 60 seconds which expands on (and does not repeat) the 1st level statements

c) 3rd Level – A further 30-60 seconds which is very detailed and shows your deep understanding of the topic.

I would suggest if you don’t have solid 1st and 2nd Level answers to the questions, your probably not ready for VCDX. The 3rd level questions, in some areas you should be strong and be able to go to this depth, in other areas, you may not, but you should prepare regardless and focus on your weak areas.

5. Giving BS answers

I can’t put this any nicer, if you think you can get away with giving a BS answer to the VCDX panel, or even a good mock panellist, your sorely mistaken.

It never ceases to amaze me, people seem to refuse to admit when they don’t know something – nobody knows everything, don’t be afraid to say, I Don’t know.

Don’t waste the precious time that you have to demonstrate your expertise by giving BS answers that will do nothing to help your chances of passing.

In a mock panel situation, take note of any questions your asked, which you dont know, or dont have strong answers too, and review your design, do some research and ensure you understand the topic in detail and can speak about it.

This may result in you finding a weakness in your design which even if your design has been accepted already, you have the chance to highlight these weaknesses in your defence and discuss the implications and what you would/could to differently – this is a great way to demonstrate expertise.

6. Not knowing about Alternatives to your design

If you work for Vendor X, and Vendor X has a pre packaged converged solution, with a cookie cutter reference architecture which you customize for each client, you could have been successfully deploying solutions for years and be an expert in that solution, but this alone doesn’t make you a VCDX, in fact it could mean quite the opposite.

If your solution is a vBlock, with Cisco UCS, EMC storage (FC/FCoE) and vSphere, how would your solution be impacted if the customer at the last min said, we want to use Netapp storage and NFS or what about if the customer dropped EMC/Netapp and went for Nutanix. How would the solution change, what are the pros and cons and how would this impact your vSphere design choices?

If you can’t talk to this, in detail, for example the Pros and Cons of for example

a) Block vs File based storage

b) Blade vs Rack mount

c) Enterprise Plus verses Standard Edition for your environment

d) Isolation response for Block verses IP storage

Then your not a Design Expert, your at best a Vendor X solution specialist.

If you do use a FlexPod, vBlock or Nutanix type solution with a reference architecture (RA) or best practices, you should know the reasons behind every decision in the reference architecture as if you were the person who wrote the document, not just customized it.

Tips for the defence

1. Answer questions before they are asked

Expanding on Common Mistake #4, as previously mentioned, you should be able to work out the vast majority of questions the panel will ask you, by reviewing your design and having others also review your work.

With this information in mind, as you present your architecture, use statements such as

“I used the following configuration for reasons X,Y,Z as doing so mitigated risks 1,2,3 and met the requirements R01,R02″.

This technique allows you to demonstrate expertise by showing you understand why you made a decision, the risks you mitigated and the requirements you met, without being asked a single question.

So what are the advantages of doing this?

a) You demonstrate expertise while saving time therefore maximizing your chance of a passing mark

b) You can prepare these statements, and potential avoid being interrupted and loosing your train of thought.

2. When asked a question, don’t be too long winded.

As mentioned in Common Mistake #4, preparing short concise answers is critical. Don’t give a 5 min answer to a question as this is likely to be wasting time. Give your level 1 answer which should cover the key concepts and decision points in around 30 seconds, and if the panel drills down further, give your Level 2 answer which expands on the Level 1 answer, and so on.

This means you can maximize your time to maximize your score in other areas. If the panel is not satisfied with your answer, they will ask it again, time permitting.

Which leads us nicely onto the next item:

3. If a question is asked twice, go straight to Level 2 answer

If the panel has asked you a question, and you gave the Level 1 answer, and later on your asked the same question again, its possible you gave an unclear or incorrect answer the first time, so now is your chance to correct a mistake or improve your score.

Think about then answer you gave previously, if you made a mistake for any reason, call it out by saying something like, “Earlier I mistakenly said X, however the fact/s are….”

This will show the panel you know you made a mistake, and you do in fact know the correct answer or the topic in question.

4. Near the end of your Defence give more detailed answers

In the first half of the 75mins, giving your Level 1 and maybe Level 2 answers allows you to save time and maximize your score across all areas.

As you get pass the half way mark and nearing the 20 min remaining mark, at this stage, you should have gone over most areas of your design and now is the chance to maximize your score.

When asked questions at this stage, I would suggest the Level 2/3 answers are what you should be giving. Where you may have given a good Level 1 answer, now is the chance to move from a good answer, to a great answer and maximize your score.


I hope the above tips help you prepare for the VCDX defence and best of luck with your VCDX journey. For those who are interested, you can read about My VCDX Journey.

In Part 2, I will go through Preparing for the Design Scenario, and how to maximize your 30 mins.


What does Exchange running in a VMDK on NFS datastore look like to the Guest OS?

In response to the recent community post “Support for Exchange Databases running within VMDKs on NFS datastores” , the co-authors and I have received lots of feedback, of which the vast majority has been constructive and positive.

Of the feedback received which does not fall into the categories of constructive and positive, it appears to me as if this is as a result of the issue is not being properly understood for whatever reason/s.

So in an attempt to help clear up the issue, I will show exactly what the community post is talking about, with regards to running Exchange in a VMDK on an NFS datastore.

1. Exchange nor the Guest OS is not exposed in any way to the NFS protocol

Lets make this very clear, Windows or Exchange has NOTHING to do with NFS.

The configuration being proposed to be supported is as follows

1. A vSphere Virtual Machine with a Virtual SCSI Controller

In the below screen shot from my test lab, the highlighted SCSI Controller 0 is one of 4 virtual SCSI controllers assigned to this Virtual machine. While there are other types of virtual controllers which should also be supported, Paravirtual is in my opinion the most suitable for an application such as Exchange due to its high performance and low latency.


2. A Virtual SCSI disk is presented to the vSphere Virtual Machine via a Virtual SCSI Controller

The below shows a Virtual disk (or VMDK) presented to the Virtual machine. This is a SCSI device (ie: Block Storage – which is what Exchange requires)

Note: The below shows the Virtual Disk as “Thin Provisioned” but this could also be “Thick Provisioned” although this has minimal to no performance benefit with modern storage solutions.


So now that we have covered what the underlying Virtual machine looks like, lets see what this presents to a Windows 2008 guest OS.

In Computer Management, under Device Manager we can see the expanded “Storage Controllers” section showing 4 “VMware PVSCSI Controllers”.


Next, still In Computer Management, under Device Manager we can see the expanded “Disk Drives” section showing a number of “VMware Virtual disk SCSI Disk Devices” which each represent a VMDK.








Next we open “My Computer” to see how the VMDKs appear.

As you can see below, the VMDKs appear as normal drive letters to Windows.



Lets dive down further, In “Server manager” we can see each of the VMDKs showing as an NTFS file system, again a Block storage device.


Looking into one of the Drives, in this case, Drive F:\, we can see the Jetstress *.EDB file is sitting inside the NTFS file system which as shown in the “Properties” window is detected as a “Local disk”.


So, we have a Virtual SCSI Controller, Virtual SCSI Disk, appearing to Windows as a local SCSI device formatted with NTFS.

So what’s the issue? Well as the community post explains, and this post shows, there isn’t one! This configuration should be supported!

The Guest OS and Exchange has access to block storage which meets all the requirements outlined my Microsoft, but for some reason, the fact the VMDK sits on a NFS datastore (shown below) people (including Microsoft it seems) mistakenly assume that Exchange is being serviced by NFS which it is NOT!



I hope this helps clear up what the community is asking for, and if anyone has any questions on the above please let me know and I will clarify.

Related Articles

1. ”Support for Exchange Databases running within VMDKs on NFS datastores

2. Microsoft Exchange Improvements Suggestions Forum – Exchange on NFS/SMB