VCAP-DCA Lab Talk Part 1: Options and Use Cases

For a practical exam like VCAP-DCA you need lots and lots of practice … and for that you need a lab.

Filtering through all the Information 

Before you build a lab you need to know the options available. You may need to spend over €1000. You can go way above this, but either way you are looking at several hundred dollars, euro or equivalent.

There are many VMware community bloggers providing really useful advice on which options you can use. if you’re like me, you may find the depth of information and options challenging. I just didn’t know which option would suit me at that point.

Establish your use cases 

In the first instance, establishing what you might need and why, can be a challenge. You almost need a lab to know what it can do and how you might improve it. It’s like living in a house – you need to live in it to figure out the uses of some rooms to suit your family and day-to-day life style.

Let’s take it back and establish some requirements:

  1. Will you access your lab only at home ?
  2. Is this a long term thing you’ve always wanted to do, or purely for VCAP-DCA or another exam? (one thing you might find is that once you get a lab you’ll be surprised how “handy” it is to do things. And you can get Not for Resale trial software for nearly everything)
  3. Do you need to bring it with you, for whatever reason, for example for better responsiveness or to demonstrate to your colleagues or customers?
  4. Do you need to have remote access to the lab, from within the house, or also from outside ?.
  5. Do you need to provide information or any other services to other people? (Some people in the community actually provide services to companies using their labs)

Knowing the answers to these questions will help you decide the best approach.

Let’s talk about three options for deploying a virtual LAB:

  • Nested
  • Physical
  • Mixed

Nested

A Nested lab is one where you are not running the VMware hypervisor on bare metal. This means the hypervisor software is not installed onto the disk of the system. You have something else installed onto the first layer. This diagram illustrates the point:

Nested Config

It works like this:

  • The outer layer is your server. On that you install Windows or MacOS as normal.
  • On top (or inside) you run a supported version of VMware Workstation or Fusion.
  • You create virtual machines inside Workstation or Fusion. You install ESXi into them.
  •  You then deploy virtual machines inside the ESXi instances.

To create a functional vSphere cluster you create multiple ESXi copies at the third layer.

And yes, it work’s great. Workstation/Fusion are powerful products that interact well with the underlying system and network as well as with tenant ESXi VMs.

One of the downsides is having to use desktops/laptops and the inherent memory limits of these systems. Typically you will be constrained at either 24 or 32 GB. Also there will be some performance overhead for some tasks, but for functional testing it should work just fine.

So we’ll come back to that later. Just remember that all of this stuff runs on a single host.

As I will outline in a later post you can run multiple setups like this and get them to talk to each other. I currently use a Gaming system with VMware Workstation and a Macbook Pro with VMware Fusion. Each one is a separate vCenter Datacentre. I use SRM in my lab to replicate VMs between them. In this case you need Gb/s networking ideally.

I hope this illustrates that while this has limits, you can do pretty much all you need with a setup like this.

Meeting Use Cases

In terms of meeting use cases above, Nested performs like this:

Use Case Ability to meet Use Case
Home Use Only Yes.
Short term or long term need Yes. May impose some longer term constraints or restrictions due to resource limits of hardware.
Must be portable  Yes. then you are limited to a laptop or macbook. Unlikely to exceed 16GB RAM.
Remote Access required? Yes.
Providing services to customers? No. Workstation class systems are not really suitable for businesses relying on levels of capacity and reslience normally associated with servers.
Some Advantages Small footprint.Low Noise and Power.Dual purpose – you can still use as Home Office System.

Highly portable (if it’s a laptop).

Easy to get up and running.

Can use simple internal network and internal storage.

Pretty simple to deploy images into the different layers and easy to manage.

Disadvantages Resource limits.Performance limitations.Does not replicate a production environment so feels different, especially network.Less scalable.

Some limitations e.g. can’t run FT, PCI passthrough etc.

Physical 

You can purchase physical servers, either tower, rack or micro-servers, and install vSphere hypervisor/software directly onto their local disks/USB drives.  So you’re replicating a server environment in your company.

The choice for this option depends on a few things:

  • Budget
  • You might need a rack for a rack server. Will this be in your office, bedroom or garage?
  • Remember the noise and power (and cooling) requirements and impacts.  This will rule this option out for some.
  • There are other options rather than rack servers that can work really well too. So the noise and cooling issues are more related to larger rack/blade servers.

If you go physical you need an external disk source for sure, and some networking, but that depends on many things. Alternatively you can use servers with disk in the chassis and a product such as VMware VSAN, which does not need external storage, but will still need networking. There you need internal SSDs and other disks.

Also…..running directly on physical means your lab will be relatively static, and is not being shut down or started up whenever you need to move around. There are people who have a couple of racks at home – mainly at VCDX level where performance testing becomes an important part of regular activities.

Meeting Use Cases

Use Case Ability to meet Use Case
Home Use Only Yes.
Short term or long term need Yes. This can probably be a great way to meet longer term requirements that are not yet known.
Must be portable  No. Unless using Intel NUC micro servers or equivalent.
Remote Access required? Yes.
Providing services to customers? Yes. This is a possibility using this class of system.
Some Advantages More scalable (memory, disk).Higher performance (across system).More expandability for PCI (NICS, HBAs, CNAs).Enterprise class redundancy.

Possible VMware hardware compatibility so may support all features of vSphere.

Some Disadvantages More expensive.Some servers need racks.Noise is the biggest downside.Rack servers need to be racked. This may require a rack or even hosting somewhere. If you can afford/arrange it this is a great option.

Hosting will require remote access probably via VPN.

 

Mixed

“Mixed” is a combination of Nested and Physical..

You have dedicated servers/systems, and on there you run something like ESXi, and inside that you create another copy of ESXi. So you’re running on servers and not using a “workstation” class product like VMware Workstation or Fusion.

Let’s say you have 3 servers. You install a copy of vSphere (ESXi) on your server. Instead of installing your normal virtual machine. You install another copy of ESXi inside the first copy.

So your virtual machines live at the third layer.

Benefits of this approach are that servers can have much more memory than desktops. And as I mentioned already memory will ultimately prevent you from doing things later that you might want to.

Meeting Use Cases

Use Case Ability to meet Use Case
Home Use Only Yes
Short term or long term need Yes.
Must be portable  No. (Intel NUC unlikely to be used in this scenario)
Remote Access required? Yes.
Providing services to customers? Yes.
Some Advantages Very similar to for pure physical setup.You may not require as many of these to run a larger amount of VMs.Scalability of nested environment will be much improved as servers have more memory.You can pack as serious amount of ESXi hosts and VMs onto a single server due to better overall system performance and higher memory.
Some Disadvantage Same as above. However it is likely you might require less of these to gain some of the same benefits.It might be an issue that you are not entirely replicating a physical environment so operationally it will feel different.

That’s it for now….. In my next post I will discuss home networking ….

 

 

 

6 thoughts on “VCAP-DCA Lab Talk Part 1: Options and Use Cases

  1. Hi Paul,

    Just wanted to add that there are some laptops that can do 32GB. For example, until recently, I had a Lenovo ThinkPad W520. It can support 32GB RAM and I also added a 512GB SSD (replacing my DVD) to it. It hosted a good size and fast lab with all machine thin-provisioned on the SSD.

    I wrote a series of posts about one of my machines here: http://atherbeg.com/2012/09/30/building-or-upgrading-a-virtual-home-lab-machine-part-i/

    That machine has 64GB of RAM and is pretty handy as a home lab machine.

    Great write up! Will look forward to the next instalment!

    Ather

    1. Hi ather,

      Great reply. Thanks for clarifying. and for adding more useful information to the pot…

      You should reply to my tweet with your blog post !!.

      Best as always,
      Paul

    2. The VCAP Test Track (which is a mobile replica of the VCAP5-DCA environment seen at VMworld and VMUGs) was initially designed and run on a Lenovo W510 with 16GB of RAM. It also normally ran off a single 2.5″ 7200RPM disk (WD Black).

      VCAP Test Track for DTA and CIA will need 32GB (at least).

  2. Great post Paul!

    I see a lot of people jump straight to the “what hardware should I buy for my home lab” without really understanding their requirements or the options available to them. This seems to be especially true of VCP candidates who, lacking the experience, aren’t even aware that a fully nested lab is possible.

    I will be sure to point them in this direction from now on.

    I am not sure about residential power costs where you are, but it’s a massive consideration here. Indeed, having an enterprise server plus disks running 24/7 can easily add upwards of a thousand dollars to the yearly power bill, so it should definitely be budgeted.

    1. Hi Luke,
      Thanks for your comments. I agree and there are plenty of great posts out there and people much more knowledgeable about laptops (Like Ather Beg) who I would point people towards. My next post is about Home Broadband, network and some of the impacts you can see there. It caused me quite a bit of hassle so it’s relevant and hopefully different and will save someone reinventing the wheel.

      All the best,
      Paul

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