Tag Archives: FlexCast

Rock-Paper-Scissors-Lizard-Spock to Making Your FlexCast Decision


We all wish picking FlexCast was as easy as playing Rock-Paper-Scissors.

In reality, the FlexCast decision is more like Rock-Paper-Scissors-Lizard-Spock.

Unfortunately, many people go down the path of Rock-Paper-Scissors-Gun-Ligntning-Devil-Dragon-Water-Air-Sponge-Wolf-Tree-Human-Snake-Fire

There is a lot of anxiety with making the FlexCast decision because it directly impacts the capabilities of the assigned users. When should I pick

  • Pooled VDI vs. Hosted Shared
  • Streamed VHD vs. Streamed VDI
  • PvD vs. Remote PC

This decision is even more challenging because there is no single question that can be asked to decide the appropriate model. So let’s not ask a single question. Let’s ask 6 J

Let’s say you have a user group that must be locked down so that they cannot make any customizations to their virtual environment. Which model would I use?

Seems easy… Hosted Shared.

Not so fast. This might not be the best option.

First, what models can support a “No personalization” requirement (I talked about the personalization requirement in a previous blog)? All of them, D’oh! Even a dedicated desktop “would” work, but seems like a bad idea. Why give users a virtual desktop that is based on a use case of complete personalization when they need no personalization?

If we narrow this down, our best option would most likely be Hosted Shared desktops (just like we originally said), but a Pooled VDI and Streamed VHD are just as capable and should be considered as good options.

What if the organization has already deployed XenDesktop to some users and currently has no deployment of XenApp? Is Hosted Shared still the best option? Not really. I would probably opt for Pooled VDI because the organization already knows how to deploy/manage. If we go for Hosted Shared, that is a new environment, a new thing to learn and support.

What if this user group is local and has applications that run pretty hot (lots of CPU, RAM or graphics)? Is Pooled VDI still the best option? Maybe, but Streamed VHD looks pretty good too.

What if solution must be cost-conscience? I’m now moving further into the Streamed VHD camp. Use local hardware instead of purchasing a lot of servers, definitely cheaper alternative.

This is how Project Accelerator determines FlexCast. It gathers information across many different categories and ranks the FlexCast models appropriately as Good, Better, Best and Bad. The one “scoring” the highest is our recommendation. Any FlexCast model receiving a single “Bad” rating in any category is removed from further consideration.

So you might be asking, what are the categories you use to rank each FlexCast model?

At the user group level, we have the following:

  1. Personalization
  2. Security
  3. Mobility
  4. Risk

At the organizational level, we also use:

  1. Technical Skillsets
  2. Business Priorities

The user group level allows us to rank FlexCast models based on capabilities, while the organizational level helps us break a tie. The model must fit the user requirements first.

If you want to learn more, then look at the “Assess-User Segmentation” section of the Citrix Virtual Desktop Handbook.

Daniel – Lead Architect

Project Accelerator
Citrix Virtual Desktop Handbook

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The importance of user personalization within your virtual desktop


I just got off the phone with Citrix helpdesk because I finally messed up my virtual desktop. I have a dedicated virtual desktop and I guess I installed/uninstalled too many things over the past few years. The same thing always happened to me with a traditional desktop. The good thing is that it only took the helpdesk a few moments to reset my virtual desktop to a base image and I didn’t have to sit and install Windows 7 and Office for the 100th time.

This experience got me to the next question from Project Accelerator: The importance of personalization.

We all know what personalization is. What rights you, as a user, have in altering the initial state of the desktop/application environment. Can you change a setting in an app? Can you install apps? Can you change OS-level settings? Can you even change the background (seriously???)

Why does personalization matter? We need to align the technical solution with the user requirements. In Project Accelerator, we break this down into three levels:

  1. No personalization: User cannot modify any desktop or app setting (similar to a kiosk)
  2. Basic personalization: User can modify user-level settings within desktops and apps
  3. Complete personalization: User can make any change, including installing applications

Easy, just pick the one most appropriate for your users group. Let’s think hard about this because if you get this wrong, your users will be ready to revolt. Imagine you gave a user a pooled desktop. They installed an app. The next day, the app is gone. User thinks this is strange. Maybe I was under severe medications yesterday and I only imagined myself installing the app. So they do it again. Bam, next day, the app is gone. Now they start to get angry and they let you know about it.

This scenario plays out all the time. If you assess your users, you should understand what level of personalization they require. The “No Personalization” item is usually the easiest to identify as these users typcially make up a very specific use case.  However, we often get into the debate between Basic and Complete.   I say when in doubt, go with complete. Your users will be happier in the long term, which will probably make you happier as well.

As you can imagine, this one decision plays a big role in determining what kind of virtual desktop the user gets, but it does more than that. This one question influences:

  • FlexCast: what type of virtual desktop the user receives
  • Deployment order of your user group
  • Which folders to redirect
  • What type of profile to use
  • What type of XenClient image to use
  • XenClient backup storage requirements

Choose wisely.

Daniel – Lead Architect

Light Users: Hosted VM-based or Hosted Shared Desktops


I recently posted a blog focusing on the resource requirements for hosted VM-based virtual desktops. These are realistic numbers and should make you wonder if the hosted VM-based virtual desktop is the most appropriate solution for all four user categories. What I found interesting was I had another blog identified as a follow-up talking about if the hosted VM-based desktop model made sense for all of the defined user groups when I started to receive emails, blog comments and twitter comments expressing the same concerns. This is great! That means many more people realizing that desktop virtualization does not always mean the hosted VM-based desktop model.

Let me explain further. As a refresher, we typically break down users into one of four groups defined as follows:

User Group Description
Light One or two applications no browser-based activity
Normal Multiple applications with limited browser-based activity
Power Many simultaneous applications with extensive browser-based activity and Internet-based applications.
Heavy Few applications but have heavy system resource requirements. Data processing, compiling, or graphics manipulation are common applications.

Of course as you move up the levels so too do the requirements for the hosted VM-based virtual desktop. But does it really make sense to have our light users running on the hosted VM-based desktop model? For light users, we typically define the following in terms of resource allocation:

User Group Operating System vCPU Allocation Memory Allocation Avg IOPS (Steady State) Estimate Users/Core
Light Windows XP 1 768MB-1 GB 3-5 10-12
Windows 7 1 1-1.5 GB 4-6 8-10

Is this crazy? Why does a user who only runs 1 or 2 applications, which are most likely line-of-business applications, require a hosted vm-based desktop environment? If you then go back to our high-level recommendations on application integration, you will see that many line-of-business applications are better served as applications virtualized on XenApp. This isn’t because desktops can’t run the applications; it is because many line-of-business applications are complex, have many dependencies, require extensive configurations. Hosting these applications on XenApp is something that has been successful for years and virtual desktops do not change that fact.

Many of the issues we’ve seen with organizations running hosted shared desktops in the past is that it doesn’t look or feel like the desktop OS. That was then, this is now. Windows 2008 can look like Windows 7. Challenge solved.

Many organizations struggle to justify transforming their desktop environment due to the costs associated. I agree, there is a cost, but the cost can be significantly reduced if you don’t go in blindly. If we use the hosted shared desktop model for our light user loads, we can save. Think about it this way, every light user will need 1-1.5GB of RAM for their hosted VM-based desktop session. Of that amount roughly 768MB of that will be just for the OS. Why does each one of the users require a full-fledged desktop OS? If we share the desktop across 100 users, we save almost 8GB of RAM. It doesn’t sound like much but what about 1000 users or more? And we haven’t even begun to discuss the impact on storage for these users.

So far we are only looking at the OS requirements; what about the application RAM requirements? Because the resources are completely shared, if the application requires 200MB to run, a large percentage of that amount can be shared across all users, helping to reduce the overall RAM requirements (and many Line-of-business applications I’ve seen, including the dependencies, need way more than 200MB of RAM).

So what is my point in all of this? Just because you are looking at virtual desktops, it doesn’t mean that you must put all of your users onto the same type of virtual desktop. Align the technology you implement with the user requirements.

Daniel – Lead Architect

The Virtual School Is In Session, Please Take your Seats


Once upon a time, there was a little school (70,000 users) with a  little problem (desktops over 5 years old) with a little idea. The school was trying to find a way to make the tax money go further. The newest desktops were 5 years old with many more approaching 10 years.  Depending on the school within the district meant different endpoints, different applications and even different quality.  With so many students having home PCs, the school was also interested in allowing these students to work with their applications while not at school.

The school decided to try something new… desktop virtualization.

But if you had to create a desktop virtualization design for a school or your organization, how would you begin? What would you focus on?  What do you think are the most important design components?  That is what we will focus on during a Ask the Architect TechTalk on June 18th at 1PM Eastern time.  Not only will we focus on the hypevisor, which is Microsoft Hyper-V, we will also focus on the three Citrix FlexCast models used, the image delivery solution, applications integration and how the XenDesktop farm is designed.

There will be many interesting points throughout the TechTalk including this one: Continue reading The Virtual School Is In Session, Please Take your Seats

I Choo, Choo Choose You


From the words of Ralph Wiggum, I Choo, Choo, Choose You [to be my FlexCast model].

Choosing the correct FlexCast model always leaves people wondering if they made the right decision.  The answer to this question requires us to look closer into the user requirements.  For example, the ABC School District Reference Design was recently published, and as can be expected from the title, it is based on a large school district (70,000 total users, 20,000 concurrent).  How did we decide which FlexCast model was most appropriate?
Continue reading I Choo, Choo Choose You