Yellow Bricks

by Duncan Epping

drs

E-Book version of the HA/DRS Deepdive?

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I’ve had this question too many times over the last couple of weeks and instead of answering all of them separately I figured I would dedicate a blog article to it so that I can reference to that. Here we go:

Q) Will the e-book version of the HA/DRS deepdive be available soon?

A) No. We have decided that we will not release an e-book (including pdf, ibook, kindle) version of the book. It required a full reformatting of the book which is simple not feasible at this point in time. As it is a “self published” book we are responsible for not only the content but also the formatting etc. Sorry about that, for “Volume 2” however we will reconsider this.

 

I hope this answers your question(s). Thanks and again our apologies, the only option is the paper version.

UPDATE: http://www.yellow-bricks.com/2011/04/05/what-an-ebook-is-this-a-late-april-fools-joke/

What have you’ve been up to?

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I got a couple of questions around what I have been up to lately as some noticed there was a slight decrease in volume from a blogging perspective on yellow-bricks. (from 4 articles per week to 2-3 article per week) Well I have been reading up on my new role but on top of that also started blogging for the ESXi Chronicles blog (add it to your RSS reader) and created a VMware Storage centric twitter account. (Follow me if you want to keep up to date on VMware storage initiatives!) The things that I’ve worked on the last couple of weeks:

  • VMware ESXi: Planning, implementation and security
    The week before VMware Partner Exchange I decided that it was time to start brushing up my ESXi knowledge. I usually dig up all the manuals and presentations I can find and start from there. This time I took a different approach however, I bought a book. The book is titled “VMware ESXi: Planning, Implementation, and Security” and is authored by a true VMTN Community hero, Dave Mishchenko.
  • Scripted install with ESXi
    Now you can kick off the automated install of your ESXi server. But wait, you probably want to see what script I used? That is what I figured, here is the script I wrote to automatically install and configure the ESXi host, it is just a simple script that I used and tested in my lab with the main purpose of showing what is possible with ESXi today. The configuration of the server will run after the first boot. I have added several “comment lines” to explain what I am doing and why.
  • Adopting ESXi, now is the time!
    Within the virtualization community we have been seeing more and more people adopting ESXi. Not only adopting it but also actively evangelizing the use of ESXi over ESX classic. The main argument being of course the reduction in operational effort involved with maintaining the platform. Last week two excellent articles were published. The first article was by Bob Plankers of LoneSysAdmin.net fame. Bob wrote an excellent article countering all often heard complaints about ESXi.

I also wrote my first KB article which discusses the impact of CPU/Memory limits with help from someone from the the GSS team. You would expect that a KB article describing the impact already existed but surprisingly enough it did not. Hence the reason I felt an official statement could prevent some of the issues we see in the field on a daily basis.

Of course that’s not it, I am working on multiple other projects which I cannot discuss yet unfortunately and participated in the VCDX Defenses at PEX. One of the things I can reveal though is that Frank and I are make plans for a volume 2 of the HA/DRS Tech Deepdive and that the sales is still going strong, thanks everyone for your help/support! (No, there will not be an e-book unfortunately, the amount of time/reformatting required did not fit our current schedule.) Keep those reviews and pictures coming though.

Want a free HA/DRS Technical Deepdive Book?

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Want a free HA/DRS Technical Deepdive Book? Watch vChat 15!

In Episode 15 of our vChat series, we have a couple of special guests with us whom I’m sure you would have heard of or if not met before, Frank Denneman and Duncan Epping. These guys embody almost all things deep-dive when it comes to vSphere and with the recent release of their new book VMware HA/DRS Deepdive and we take the opportunity to ask about the background behind the book, whether an electronic version is in the pipeline along with their plans for any future publications. We discuss VMware Partner Exchange (PEX) 2011. Other topics, as you’d imagine, cover the VMware iPad app (and the potential security issues) and their home vSphere labs.

Watch it here!

Shares set on Resource Pools

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During our session at the Dutch VMUG Frank was explaining Resource Pools and the impact of limits and reservations. As I had the feeling not everyone in the room was using resource pools I asked the following questions:

  1. How many people are using Resource Pools today?
    • Out of the roughly 300 people who attended our session 80 showed their hands. The follow-up question I asked was…
  2. How many people change the Shares setting from the default?
    • Out of those 80 hands roughly 20 people raised their hands and that lead me to the next question…
  3. How many people change the Shares value based on the amount of VMs running in that Resource Pool?
    • Now only a handful of people raised their hand.

That is what triggered this post as I believe it is an often made mistake. First of all when you create a Resource Pool there are a couple of things you can set a reservation, a limit and of course shares. For some reason shares are often overlooked. There are a couple of things I wanted to make sure everyone understands as judging by the numbers of hands that were raised I am certain there are a couple of common misunderstandings when it comes to Resource Pools:

  • If you create a Resource Pool a default Shares value is defined for the resource pool on both Memory and CPU
  • Shares specify the priority of the resource pool relative to other resource pools on the same level

This means that even if you don’t touch the shares values they will come into play whenever there is contention. This also means that the resource allocation on a VM level is dependent on the entitlement of the resource pool it belongs to.

Now what is the impact of that? I guess I should quote from the “The Resource Pool Priority-Pie Paradox” blog post my colleague Craig Risinger wrote as it clearly demonstrates the issues that can be encountered when Resource Pools are used and Shares values are not based on the relative priority AND the amount of VMs per pool.

“Test” 1000 shares, 4 VMs => 250 units per VM (small pie, a few big slices):

“Production” 4000 shares, 50 VMs => 80 units per VM (bigger pie, many small slices):

I guess this makes it really obvious that shares might not always give you the results you expected it would.

Another issue that could arise is when Virtual Machines are created on the same level as the Resource Pools…. Believe me it doesn’t take a lot for a single VM to have higher priority than a Resource Pool in times of contention.

Again, whenever you create a Resource Pool it will “inherit” the default shares value, which equals a 4vCPU/16GB Virtual Machine, and whenever there is contention these will come into play. Keep this in mind when designing your virtual infrastructure as it could potentially lead to unwanted results.

European distributor for the HA and DRS Technical Deepdive

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Frank published the following yesterday, but as many people have asked me about this I thought I would post it as well. For those who were looking for a European distributor of our book:

As of today, our book “vSphere 4.1 HA and DRS Technical Deepdive” can be ordered via ComputerCollectief. Computercollectief is a dutch computer book and software reseller and ships to most European countries. Using Computercollectief, we hope to evade the long shipping times and accompanying costs.

Go check it out. http://www.comcol.nl/detail/73133.htm

Comcol expects to be able to deliver at the end of this month.