Kirx' Blog - kirxblog.wordpress.com

Should the App-V Sequencer be installed into the Snapshot Image? | August 14, 2010


Introduction

In order to create a persistent state of the Sequencer Workstation for App-V Sequencing, it is recommended to either use Virtual Machine Snapshots or some Hard Disk Imaging Technologies. The reason for creating such a persistent state is that Sequencing always should be performed from a “clean” workstation and imaging or using snapshots are two very fast ways to accomplish this.

The Common Sense about that persistent image is that it should reflect the “Core (Client) Image” to certain extends and also it should not have any background services active that negatively influence the sequencing process. Microsoft’s Sequencing Guide whitepaper describes that more detailed.

But what about the Sequencer Software itself: should it be installed before the image gets created – or should it be installed each time after the image has been reverted?

In the past, there was an easy answer to that question. It was caused by a special behaviour (you may call it a bug) of the Sequencer Software – and this answer was: Do not install the Sequencer before creating the image. Essentially, the reason for this advice was that the Sequencer sometimes generated equal Package GUIDs (instead of random GUIDs) – it did not do that always, but explaining that would be out-of-scope here. Therefore, the Sequencer software usually was not installed before creating the image…

Article History:

This article has been modified significantly several times.

2010-01-15:    Original Post

2010-03-15:    I “disabled” the original post because of an article by Tim Mangan (http://www.tmurgent.com/TmBlog/?p=202). Tim indicated that the 4.6 version of the App-V Sequencer re-introduced a bug that was solved before. His recommendation is to not run the Sequencer Software before creating a VM Snapshot. Being cautious, I followed his advice which required to review my original post entirely.

2010-08-14:    Doing some tests and gathering customer’s and peer’s feedback I was not able to reproduce Tim’s finding. Also he was not able (anymore) to provide some step-by-step guidance. Therefore I am pretty sure you can install and run the Sequencer Software before creating the VM image. So, I basically stick on the first version (with some minor changes). However, I did not yet inject the opportunity to store the Sequencer’s Configuration. Advice for this can be found at the following article:

2011-05-03:   Currently there is a community discussion going on about duplicate GUIDs appearing (or not?) in App-V 4.6 SP1. I consider updating this article or creating a new one based on the discussion’s result. In between, you my follow  https://kirxblog.wordpress.com/2011/04/13/what-if-duplicate-guids-never-appear-a-reply-to-the-saga-of-duplicate-guid/

Why you should install the Sequencer each time after you reverted the image?

The explanation for this “sort-of Microsoft” recommendation is that the Sequencer Software gets updated by Microsoft from time to time – and if it is installed in the image a while ago, chances are low to have an up-to-date Sequencer doing its job.

So, if you follow that advice and install the Sequencer Software after the image has been reverted, you probably have the most current version of it running.

And that’s it? So you simply install the Sequencer each time after you reverted the image and you are fine? Well, let’s think about that further:

Why you should not install (the newest version of) the Sequencer each time you reverted the image

One reason for not installing the newest version of the Sequencer each time is synchronization between Sequencer and Client: You never should have a Sequencer that is newer than the App-V Client being used. And because you probably don’t update your Clients every week or month, you also shouldn’t do so with your Sequencer.

The second reason is more, let’s say, indirect: Microsoft also recommends having the latest Windows Updates on the Sequencer. So, after you reverted the image, you first run MS Updates each time. After that, you install the Sequencer using its most up-to-date version (or at least the version that reflects the Client’s version number). Following that “official” guideline, you bring your Sequencer machine to a current state each time before you start sequencing – so you add another 15-30 minutes on each Sequencing process. That you do. I mean, that you really do. Don’t you?

You may agree that bringing the Sequencer (Software version and Windows Updates) to the very most current state before each sequencing is not very handy – but preparing an image and perpetually reverting it for several months is not a good way either…

So, what is a smart way between using a most up-to-date Sequencer Workstation and a practical image handling?

Think about an image staging strategy:

  • One stage is used for your daily Sequencing. Let’s call that the “Working Image”
  • Another stage is used as a more “mid term” template for that Working Image. Let’s call that the “Image Template”

The idea is that you DO NOT install the Sequencer Software to the Image Template, but you install certain MS Updates (that are present on your clients as well) on that template. This image gets updated each time a new wave of Windows Updates is deployed to the client machines. The OS image thus contains current MS updates and Windows updates are in-sync between the Sequencer and Clients.

Periodically, you create a copy from that “Image Template” and install the Sequencer software into it. This becomes the Working Image that each Sequencing Engineer will be using for daily sequencing. How long this “period” lasts or how often you stage your images depends on your Windows and Sequencer update frequency. I’d tend to one or two months, but shorter or longer periods might better fit you requirements.

To summarize, there is no Yes or No answer for the question about installing the Sequencer Software into the sequencing image. Personally, I recommend to implement that two-stage solution. This seems to be the most applicable solution to have a quite “stable” Sequencer VM without forgetting to apply new OS and Sequencer Software updates.

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2 Comments »

  1. […] The latest component to upgrade should be your production App-V Sequencer. However, I told you to test your applications with the new versions first, so you may already have an 4.6 Sequencer to re-sequence applications that require that. Upgrading the Sequencer is a perfect situation to review the Sequencer Recommendations including Anti Virus, Microsoft Updates and Core Component Updates. This has been discussed briefly in my blog here. […]

    Pingback by How to upgrade to Microsoft Application Virtualization 4.6 « Kirx' Blog — February 23, 2010 @ 12:29

  2. […] workstation and imaging or using snapshots are two very fast ways to accomplish this. read more… […]

    Pingback by - Cliff Davies — May 4, 2011 @ 18:33


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