All posts by Christian Mohn

Written by . Christian is the owner of vNinja.net and a vSoup.net Virtualization Podcast co-host.

Opinion: Is Hyperconverged the be-all, end-all? No.

First off, this is not meant to be a post negating the value of current hyperconverged solutions available in the market. I think hyperconverged has it’s place, and for many use cases it makes perfect sense to go down that route. But the idea that everyone should go hyperconverged and all data should be placed on local drives, even if made redundant inside the chassis and even between chassis, is to be blunt, a bit silly.

Parts of this post is inspired by a recent discussion on Twitter:

I don’t believe that replacing your existing storage array with a hyperconverged solution, regardless of vendor, by moving your data off the array and on to the local disks in the cluster makes that much sense. Sure, keep your hot and fresh data set as close to the compute layer as possible, but for long time archiving purposes? For rarely accessed, but required data? Why would you do that? Of course, going hyperconverged would mean that you can free up some of that costly array space and leave long term retention data on the array, but does the hyperconverged solution of choice let you do that? Does it even have FC HBA’s? If not, is it cost effective to invest in it, while you at the same time need to keep your “traditional” infrastructure in place to keep all that data available?

To quote Scott D. Lowe:

Any solution that uses standalone storage is not hyperconverged. With a hyperconverged solution, every time a new node is added, there is additional compute, storage, and network capability added to the cluster. Simply adding a shelf of disks to an existing storage system does not provide linear scalability and can eventually lead to resource constraints if not managed carefully.

Doesn’t that really show one of biggest the problems with a hyperconverged infrastructure? If you need to scale CPU, Memory AND Storage at the same time, it makes perfect sense. But what if you need to scale one of the items? Individually? Why should you have to buy more CPU, and licenses, if all you wanted was to add some more storage space?

Of course, this brings the discussion right back to where it started, if you want to scale the various infrastructure components individually, then hyperconverged isn’t the right solution. But if hyperconverged isn’t the solution, and traditional “DIY” infrastructures have to many components to manage individually, then what? Sure, the Software Defined Data Center looks promising, but at the end of the day, we still need hardware to run the software on. The hardware may very well be generic, but it’s still required.

Interestingly enough, a post by Scott Lowe (no, not the same one as quoted above), got me thinking about what the future might hold in this regard: Thinking About Intel Rack-Scale Architecture. To get to the point where we can manage a datacenter like a hyperconverged cluster, and still be able to scale vertically as needed, we need a completely new approach to the whole core architecture of our systems. Bundling CPU, Memory, Storage and Networking in a single manageable unit doesn’t cut it in the long run. Now that the workloads are (mostly) virtualized, it’s time to take a real hard look at how the compute nodes are constructed.

Decoupling CPU, Memory, Storage Volume, Storage Performance and Network into entirely modular units that can be plugged in and scaled individually makes a whole lot more sense. By the looks of it Intel Rack-Scale Architecture might just be that, I guess we’ll see down the road if it´s actually doable.

The software side of things are moving fast, and honestly, I’m kind of glad that hardware isn’t moving at the same pace. At least that gives us breathing room enough to actually think about what we’re doing, or at the very least pretend that we do.

Need the vSphere Client? VMware Has You Covered.

One of the more popular posts, currently in third place, on vNinja.net is my list of vSphere Client direct download links posted back in March 2012.

Thankfully William Lam had the same idea, and got a new Knowledgebase Article published: Download URLs for VMware vSphere Client (2089791). Please use that article as the official download link documentation from now on.

Obligatory: My VCAP-DCA 550 Experience

I finally took the plunge, and sat the VDCA550 exam yesterday. The VCAP5-DCA certification has been on my todo list way to long, and I’m glad I can now tick that box and move on.

The VDCA550 exam is held in a live lab environment, with approximately 23 lab activities, which is the subsequently scored after the exam is finished. This means that you do not get an immediate pass/fail summary at the end of the exam, but you’ll be feverishly checking your email until the score report is sent to you from VMware.

Preparation tips?

  1.  Hands-on experience. There is no substitute for real experience when it comes to this exam. It’s a lab and you need to be able to perform the tasks presented to you. No amount of reading will prepare you for that, unless it’s also accompanied by actually working with the products.
  2. VCAP5-DCA Official Cert Guide: VMware Certified Advanced Professional 5- Data Center Administration. I’ll be writing a more detailed review of the study guide later, but this book was invaluable for my preparation. Even if the book is mainly focused on the older VDCA510 exam, it also contains a chapter highlighting the changes in the blueprints between the 510 and 550 exams which was really helpful. The best part of the study guide is Chapter 10: Scenarios which goes through the certification blueprint and hands you specific tasks for each section. Get the book and do those, practicing will save you valuable time on exam day.
  3. Read the official vSphere documentation. End to end.
    Familiarize yourself enough with it, to the point that you know what keywords to search for if you get stuck on the labs.

Exam tips?

  1. Time management. You get your allocated minutes, and that’s it. I was forcefully logged out of the lab environment as soon as the time ran out, and I had 4 labs left to complete at that time. Don’t get stuck on particular labs for disproportional amounts of time. If you get stuck on something, cut your losses and move on. You can always return to a lab later if you have time for it. It’s better to score a few points extra by completing other labs, rather than losing points on a lab you end up not finishing anyway.
  2. Open up the documentation and the knowledgebase in the lab browser. That speeds up searches, and if you know your way around those resources before you sit the exam, they can be a real lifesaver.
  3. As with “traditional” multiple choice exams, read the lab descriptions carefully. Some lab descriptions are very clear on what is the expected outcome, others are more subtle. Make sure you understand the task at hand before starting on it.

The Exam?

I really enjoyed it. No, seriously, I’m not kidding. This is the most fun I’ve ever had while actually working on obtaining a certification. The fact that you get to do real world administrative tasks, without multiple choice memory games was a refreshing experience. You still need to know your stuff, but since you have the vSphere documentation and VMware Knowledgebase available to you during the exam, you can look it up if needed. See Bullet #3 above.

Working with the lab setup was a bit sluggish at times, especially when scrolling, something that require frequent screen updates, but not as bad as I thought it would be. I was really lucky, as the turn-around time for scoring of my exam was just shy of 30 minutes after finishing the exam, something that saved me a lot of agonising about my poor exam time management skills.

One last thing: I really hope VMware Education opens the door for more test centers in Norway. I had to fly to Oslo from Bergen to sit the exam, something that drives the cost obtaining it dramatically higher. We have local test centers in Bergen, but they are not allowed to offer the advanced level exams from VMware. If I had the ability to sit this exam locally, Bergen is Norway’s second largest city after all, I probably would have done this a long time ago. I almost missed my exam when my morning plane was cancelled, and when I finally got to Oslo my taxi driver had problems finding the test center. I got there just in time though, but if I had got there much later, I would have set my employer back the exam fee, the plane tickets, a taxi bill AND a day of lost productivity. Of course, I could have flown in the day before, but that would have added hotel bills to the cost equation as well.