Yellow Bricks

by Duncan Epping

ha

HA / DRS Deepdive…. euuh I mean the audit

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A couple of weeks ago Alan Renouf contacted me and asked me if it was okay to turn some of our best practices mentioned in the book into PowerCLI code. I thought about it for 0.00001 seconds and yelled: hell yeah! Alan worked on it for a couple of days over the last couple of weeks and this is the result. Alan hasn’t been able to get the full book into his audit script, but knowing Alan he will get their in a couple of weeks (no pressure). Not only does the outcome of the audit script look really cool, it is also very useful. I will be working with Alan on refining and enhancing it over the next couple of weeks so check Alan’s website on a regular basis for updates. Once again, Alan great work…

VMworld Public Voting

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As Mr Sloof already revealed VMworld Public Voting started today… I have submitted multiple sessions, some which are directly job related and others which are more community focused. As I was part of the voting committee for the Technology and Architecture track I know how many great sessions were submitted and how difficult it will be to get your session approved. (almost 400 submissions for that track alone and less than 40 slots) There are two particular sessions which I will need YOUR help with and I hope you guys are willing to vote on these. These are not the typical powerpoint slide sessions, yes you can get a lot out of those but after seeing slide 8326th of the day you tend to get a bit bored. This is your chance to change VMworld and vote for something different:

  • TA 1956 – The ESXi Quiz Show
    Join us for our very first ESXi Quiz Show where teams of vExperts and VMware engineers will match expertise on technical facts, trivia related to all VMware ESXi and related products. You as the audience will get 40% of the vote. We will cover topics around ESXi migration, storage, networking security, and VMware products. As an attendee of this session you will get to see the experts battle each other. For the very first time at VMworld you get to decide who leaves the stage as a winner and who does not.
  • TA 1682 – vSphere Clustering Q&A
    Frank Denneman and Duncan Epping will answer any question with regards to vSphere Clustering in this session. You as the audience will have the chance to validate your own environment and design decisions with the Subject Matter Experts on HA, DRS and Storage DRS. Topics could include for instance misunderstandings around Admission Control Policies, the impact of limits and reservations on your environment, the benefits of using Resource Pools, Anti-Affinity Rules Gotchas, DPM and of course anything regarding Storage DRS. This is your chance to ask what you’ve always wanted to know!

http://www.vmworld.com/cfp.jspa

The vSphere Clustering Q&A is obvious I guess. Frank and I did this session at the Dutch VMUG and the place was packed and it a cool very informative session with many great questions some which literally had our heads spinning.

The Quiz Show is kind of my baby. I came up with the Quiz Show before VMworld 2010 but as I was working on the VMworld Labs it slipped my mind and I was too late to enter it in to the system. This year however I contacted my friends Pablo Roesch and John Troyer and we had a couple of conference calls about this one… I promise you, if we can pull this one off it is going to R O C K. vExperts battling VMware employees on virtualization knowledge! Just imagine who could reach the finals, who could get eliminated during the pre-rounds… Wouldn’t it be cool if Chad Sakac and Vaughn Stewart make it in to the finals, or how could would it be when Eric Sloof gets eliminated during the pre-qualifying rounds? Yes, it is going to be EPIC, the battle of the year…

There’s another community session, and this not only has multiple top bloggers but also 4 VCDX’s : TA 1425 Ask the Expert vBloggers (Chad Sakac, Scott Lowe, Rick Scherer, Frank Denneman and I). Vote!

What? An ebook? Is this a late April Fools’ joke?

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No it isn’t a late April Fools’ joke… And we never expected this to actually happen to be honest. Last week I had discussion about the ebook on twitter and people were convinced that ebooks are the way to go. I won’t deny that and I know Frank agrees with me on this as well but the fact of the matter is that we just didn’t have the time to do all the reformatting work. I asked once again on twitter if someone knew any tools that we could leverage or if someone could give us a hand. The last 4 times I asked this question no one responded and again hardly anyone did, however a close relative of mine did contact me and told me he had some tools that could possibly help us. I forwarded the PDF and the DOCX file and within a couple of hours I received an almost clean .html file back. The email also contained a very important tip, Mobipocket Creator. So I installed it and added the html file to it and clicked “Convert”….

Yes it was close, but not close enough to be published yet. I shared the book with Frank and both of us opened it up in our Kindle App and reviewed the layout. We marked all the pages that had some glitches and started editing those. We expected to be done in a couple of hours but it ended up being a full day again for both of us… but who cares the result is worth it.

After doing research on the Kindle Store we had another decision to make; pricing. We noticed that some ebooks are more expensive than the paper version, WHAT? We didn’t want to do that. We never expected to release this and every copy sold is an extra copy sold of our book and we know that many who wanted the ebook bought the paper version instead so we decided to make it cheap, almost half the price of the cheapest vSphere book on the list (calling all publishers, revisit your pricing strategy!) and $ 17.45 less than the paper version.

But before we give you the link, one of the most asked questions… Why Kindle? Well Kindle happens to be a multi-platform solution. The Kindle Application is available for Mac, Windows, iPad, Android, Blackberry, Windows Phone 7. Which made us believe that if we had to pick one format Kindle was the way to go.

So without further ado we present: vSphere 4.1 HA and DRS technical deepdive, the ebook…… for only $ 7.50. Pick it up,

Frank & Duncan
ps: it is also available in the UK Kindle Store for £5.36.

das.failuredetection time and the isolation response

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I had a discussion on the VMTN forums about this last week and the question basically was, what should my das.failuredetection time be set to when the isolation response is set to “Shut down”.

Lets first explain what the das.failuredetectiontime is, I described it on our book as follows:

Failure Detection Time is basically the time it takes before the “isolation response” is triggered. There are two primary concepts when we are talking about failure detection time:

  • The time it will take the host to detect it is isolated
  • The time it will take the non-isolated hosts to mark the unavailable host as isolated and initiate the failover

So what does this have to do with your Isolation Response? Well not much actually, and that might sound weird but it had me thinking about it for a second as well….

What if your Isolation Response is set to “Shut down” and an isolation occurs? Well in that case HA will try to “Shut down” the VMs in a clean way when Isolation has been detected. HA will do that on the 14th second. On the 16th second the restart will be initiated. So that leaves your VMs exactly two second to shut down in a clean way….So two questions pop-up immediately:

  1. What if I increase the das.failuredetectiontime?
  2. What are the chances restarts happens in time?

Increasing the das.failuredetectiontime wouldn’t make a difference as the “2 second” gap will just move up as well. HA will always ping the isolation address on “das.failuredetectiontime – 1” and it will always initiate the restarts on “das.failuredetection + 1”. In other words, 2 minutes or 20 seconds, it makes no difference. I guess a nice diagram makes this a bit clearer:

(created by Frank D. for our book)

So what are the chances these restarts will occur within 16 seconds? Slim indeed. So when will they be restarted? Well a year ago I wrote this article and the following still applies for vSphere 4.1:

  • T+0 – Restart
  • T+2 – Restart retry 1
  • T+4 – Restart retry 2
  • T+8 – Restart retry 3
  • T+8 – Restart retry 4
  • T+8 – Restart retry 5

In other words, if T+0 fails the restart will be retried 2 minutes later. If that one fails the restart will be retried 4 minutes later. (2+4 = 6 minutes after the initial restart) So as you can see selecting “shut down” will more than likely increase your restart latency and this needs to be taken into account for your SLA.

HA/DRS Deepdive now available on Amazon.co.uk and Amazon.de

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After 14 emails with absolutely no reply whatsoever our book, vSphere 4.1 HA and DRS Technical Deepdive, popped up on both the German and UK version of Amazon. For those who haven’t ordered it yet through comcol.nl you can also get it here:

Sorry about the delay and I hope they will continue selling it for a very long time. (It seems they don’t have it on stock currently so delivery might take a while.)

<edit – 15/03>

And in France as well through Amazon I just noticed

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