How I flunked my VCAP5-DCD / How do I speak design?

31 10 2012

Man With Computer by graur razvan ionut - Image courtesy of freedigitalphotos.net If you are reading this title and am wondering how I managed to flunk that test. First, thank you for your confidence in me. Secondly, there was one basic thing that was missing from my preparation:

rest

During VMworld in Barcelona (and also during VMworld in the US), there was a 50% discount for people trying to obtain their VCP, or one of the VCAP certifications. Since I thought I would save the company some money, I went ahead and scheduled the test during the conference, and boy was that a mistake.

While there are certain key elements to preparing for a test like the VCAP5-DCD (some of which I’ll go in to a bit further down in this post), there are basics that you won’t be able to get around.

I was actually working during they conference, working at the VMworld Hands-on Labs. If that wasn’t enough, working for a vendor at a conference usually also means that you have more appointments, combine that with meeting up with customers during the parties, or going to dinner with folks, and all of the other stuff surrounding the conference, and you will end up just being tired at a certain point.

I made a major mistake of underestimating how fit I would be, which meant that I was actually starting to nod off after about 2 hours in to my certification. 4 hours is a long time to sit an exam, and folks like Jason Boche reported have described several tips on how to prepare for the exam. Unfortunately, I wasn’t fit enough and only scored 290 points, which means I missed the 300 point passing grade. So my top tip? Make sure to rest up and be fit for the exam!

There are plenty of resources describing the exam itself, and you can find some useful tips on blogs like thesaffageek.co.uk or the vBrownbags, but trust me, being well rested before the exam is one of the key things. All in all, I think the exam is very fair. You will encounter Visio like parts of the test where you are designing a solution or mapping out dependencies, there are drag and drop parts to it where you will drag boxes with keywords or design parts to their counterparts. And finally, there are the normal multiple choice parts.

You will be reading for 3.5 hours, up to 4 hours for non-native English speakers, and that means that there is just a massive amount of text to get through. Also, if you are not designing environments on an everyday basis, there is a thing that will bite you in the proverbial rear end, and that is being comfortable with 4 major categories that you will encounter in almost every question in the test.

¿Habla design?

Yes, Habla is Spanish, and when it comes to the 4 major categories, if you don’t use them every day, this may come off as Spanish to you. Here they are:

  • Requirement
  • Risk
  • Assumption
  • Constraint

Seems easy enough, doesn’t it?

“I require you to wear your seatbelt. If you don’t, you risk your life when getting in to an accident. Thats because, if you don’t, I’m assuming you’ll fly out the window when you get in to a crash. And yes, wearing the seatbelt will constrain your movement in the driver’s seat, but who would want you moving all over your car while driving anyway?”

If you put it like that, most people will comprehend what is meant. Then, when you talk to a customer, things get more vague, and quite a few people who I’ve spoken to, will have the biggest problem in distinguishing between a requirement, a consumption and a restraint. If a sentence actually start with “I assume that…” or “I require you to…” things are relatively simple.

I’ve been trying to bulk up on the definitions that are used by VMware in their certifications, and what was of help to me was for example the “Designing VMware Infrastructure” training videos by Trainsignal.

Scott Lowe, actually takes you through the various steps in creating a logical and physical design. He gives you a headstart on things to consider when you are actually designing (including some tools you can use like mind mapping software), and he goes over the design terminology.

The latter part is actually what I personally think is missing for a lot of people. They know what the technical limitations are, and will be able to look them up. They’ll be able to get their head wrapped around the physical design, and there are a lot of smart folks out there that grasp how things interact and can give a holistic overview.

But then you get to the actual lingo, and that’s where some small things may help you make it click up in your head. :)

An example I found very striking was the notion that an assumption is always coming from the view of the architect, not the business:

Assumptions vs. constraints – ©Trainsignal

The business will be able to tell you what the Vendor is that you are going to use for your network gear (there’s a constraint for ya), and tell you that they want to have an availability of 99.99% for their HR application (there’s your requirement). But you may need to assume that the bandwidth that is available to you for replication, won’t be shared by environments that were out of scope for your design (and that could also be a risk). It is something that you might be able to eliminate by asking further questions, but it could be an assumption for a final design.

Since this is a topic that I’m dealing with in preparation for my re-take of the VCAP5-DCD, I’ll be posting some updates here with the resources I’ve used, and just put some things out there for you to take a stab at, and then I’ll see if I’m any good at design, and I’ll find out where I can improve. Also, if you think I already botched it in the example I gave here, let me know and leave a comment. It will help me prepare better.


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Categories : Uncategorized

VMware releases Fusion 5

23 08 2012

Some folks on Twitter already spotted it: It seems like along with the release of VMware Workstation 9, the guys and girls over at VMware also released Fusion 5.

And with this new release come some expected things. As always, it’s bigger, better and faster. It adds suport for some of the new operating systems that are out there, for example, there is full support for Mountain Lion, and suppport was added for the new MacBook Pro with retina displays. Windows 8 support is finally built in, and they didn’t only think about the Redmond users, but also added 3D desktop support for selected Linux distributions, and one really cool feature (if your Mac is new enough to support it) is that you can use Airplay to display your VM on a TV using an Apple TV.

VMware claims that there are over 70 new features in the new version of Fusion, but I wasn’t able to locate the entire list as of yet. If I do find that list, I’ll be sure to add it to my post. In the meantime, here is the marketing shortlist:

  • Optimized for OS X Mountain Lion
  • Optimized for Windows 8
  • Designed for latest Macs
  • Faster performance
  • Retina Display Optimization
  • USB 3 support
  • Enhanced battery management
  • Enhanced UI
  • 1-click snapshot
  • Linux 3D
  • Embedded Learning Center

In the meantime, if you purchased your copy of VMware Fusion 4 from July 25th through September 30th, 2012, you are covered by the VMware Fusion “Technology Guarantee Program”, and you are eligible for a complimentary electronic upgrade to VMware Fusion 5. You can find out all about that here: http://www.vmware.com/support/product-support/fusion/faq/licensing.html?cd=4&hl=en&ct=clnk

If you want to test out this new version, go right ahead and download a trial here: http://www.vmware.com/go/tryfusion, or to immediately purchase the new version, follow this link: http://www.vmware.com/go/buyfusion. Be sure to do a quick Google search on discount codes, since there are bound to be some upgrade offers out there. :)


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Categories : Fusion, Uncategorized, Virtualization, VMware

Shorts: How to reboot a Cisco UCS 6100 series fabric interconnect

5 07 2011

I actually had this written down in my notes somewhere, and today a colleague of mine called me because he was having some issues. Since it’s not necessarily obvious, and others might be having the same problem, I thought I’d post a quick note here.

To reset the fabric interconnect on a Cisco UCS 6100 series, connect via your serial cable or use putty to ssh in to your fabric, and use the following commands:

connect local-mgmt [enter]
reboot [enter]

Obviously you leave out the space after the command, and the [enter] should be replaced by you actually pressing the enter key. Not sure if this is of help to folks out there, but I figured it’s more useful out here than in my private notes.

Update – July 10th:

Dan gave a good hint in the comments, that you might want check if the fabric interconnect you are trying to reboot is the primary or the subordinate, so here goes.

Connect to your fabric interconnect just like you did in the top example, and enter the local management:

connect local-mgmt
Now, check to see the state of the fabric interconnect you have attached to:
show cluster extended-state

This will give you a bunch of output, but there is one part that you are interested in more than anything else:
B: UP, SUBORDINATE
A: UP, PRIMARY

B: memb state UP, lead state SUBORDINATE, mgmt services state: UP
A: memb state UP, lead state PRIMARY, mgmt services state: UP
heartbeat state PRIMARY_OK
At the prompt, you can see (and hopefully you already knew to begin with) to what node or member you are connecting to. If you are at the node that is in a subordinate state, use the following command to change the state of the node you are rebooting to subordinate:
cluster lead a
or
cluster lead b
Where a or b is the node that you want to become subordinate. After that you can reboot the respective member


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Categories : Cisco, UCS, Uncategorized

Shorts: What is it about cpuid.corespersocket on vSphere?

3 08 2010

Time for another short! The google searches leading to this blog show searches coming in based on the cpuid.corespersocket setting. In this short I’ll try to explain what this setting is for and how it behaves. So, let’s dig right in!

The cpuid.corespersocket setting

In a sense, you would assume that the name of the setting says it all. And in a sense, it does. In the physical world, you will have a number of sockets on your motherboard, this number of sockets is normally also the number of physical CPU’s that you have on said motherboard (at least in an ideal world), and each CPU will have one or more cores on it.

Wikipedia describes this in the following way:

One can describe it as an integrated circuit to which two or more individual processors (called cores in this sense) have been attached.

…..

The amount of performance gained by the use of a multi-core processor depends very much on the software algorithms and implementation. In particular, the possible gains are limited by the fraction of the software that can be parallelized to run on multiple cores simultaneously; this effect is described by Amdahl’s law. In the best case, so-called embarrassingly parallel problems may realize speedup factors near the number of cores, or beyond even that if the problem is split up enough to fit within each processor’s or core’s cache(s) due to the fact that the much slower main memory system is avoided.

Now, this sounds quite good, but some of you may ask what kind of influence this has on my virtualized systems. The most obvious answer would be “none at all”. This is because by default your virtualized system will see the cores as physical CPU’s and be done with it.

So, now you are probably wondering why VMware would even distinguish between cores and sockets. The answer is quite simple; It’s due to licensing. Not so much by VMware, but by the software or operating system that you would like to virtualize. You see, some of that software is licensed per core, and some will license by the number of sockets (some even combine the two).

So how do I use it?

As with all things computer related… It depends. When you are using ESX 3.5 you have no chance of using it. With ESX 4, you can actually use this feature, but it is not officially supported (someone please point me in the right direction if this is incorrect). And starting with ESX 4.1 the setting is now officially supported, and even documented in the VMware Knowledge Base as KB Article: 1010184.

Simply put, you can now create a virtual machine with for example 4 vCPU’s and set the cpuid.corespersocket to 2. This will make your operating system assume that you have two CPU’s, and that each CPU has two cores. If you create a machine with 8 vCPU’s and again select a cpuid.corespersocket of 2, your operating system will report 4 dual-core CPU’s.

You can actually set this value by either going this route:

  1. Power off the virtual machine.
  2. Right-click on the virtual machine and click Edit Settings.
  3. Click Hardware and select CPUs.
  4. Choose the number of virtual processors.
  5. Click the Options tab.
  6. Click General, in the Advanced options section.
  7. Click Configuration Parameters.
  8. Include cpuid.coresPerSocket in the Name column.
  9. Enter a value ( try 2, 4, or 8 ) in the Value column.

    Note: This must hold:

    #VCPUs for the VM / cpuid.coresPerSocket = An integer

    That is, the number of vCPUs must be divisible by cpuid.coresPerSocket. So if your virtual machine is created with 8 vCPUs, coresPerSocket can only be 1, 2, 4, or 8.

    The virtual machine now appears to the operating system as having multi-core CPUs with the number of cores per CPU given by the value that you provided in step 9.

  10. Click OK.
  11. Power on the virtual machine.

If the setting isn’t shown, for example for those who want to experiment with it under ESX 4.0, you can create the values in the following way:

  1. Power off the virtual machine.
  2. Right-click on the virtual machine and click Edit Settings.
  3. Click the Options tab.
  4. Click General, under the Advanced options section.
  5. Click Configuration Parameters.
  6. Click Add Row.
  7. Enter “cpuid.coresPerSocket” in the Name column.
  8. Enter a value ( try 2, 4, or 8 ) in the Value column.
  9. Click OK.
  10. Power on the virtual machine.

To check if your settings actually worked, you can use the sysinternals tool called Coreinfo on your Windows systems, and on Linux you can perform a simple “cat /proc/cpuinfo” to see if everything works.


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Categories : Uncategorized, Virtualization, VMware, vSphere


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