Category Archives: Windows 7

VDI Resource Allocation

I have seen a lot of scalability reports lately around desktop virtualization. This is good in that we can start to see how the different things we do can provide better capacity. However, one thing that does trouble me is when I see tests only allocating 512 or 768MB of RAM to a Windows 7 VM. Sure it works. And yes it does successfully complete the scalability test, but remember what the scalability test is testing. It is not telling you how many users YOU will get. It is telling you how well the infrastructure can scale and what bottlenecks we might experience when the hardware is stressed. Unfortunately, because of these tests, too many people believe that they too can roll out a virtual Windows 7 desktop on 512MB of RAM. I wish that was the case. In fact, I bet Microsoft wishes that was the case as well. But I’m sorry to say, but sadly it’s true that it is not.

I wanted to provide you with what we (myself, Nicholas Rintalan, Doug Demskis and Dan Allen) figure is a reasonable estimation for resource allocation for Windows 7 and Windows XP desktops when delivered in the hosted VM-Based virtual desktop model (or VDI for short).

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
Normal Windows XP 1 1-1.5 GB 6-10 8-10
Windows 7 1 1.5-2 GB 8-12 6-8
Power Windows XP 1 1.5-2 GB 12-16 6-8
Windows 7 1-2 2-3 GB 15-25 4-6
Heavy Windows XP 1 2 GB 20-40 4-6
Windows 7 2 4 GB 25-50 2-4

See anything shocking? How about 1.5 GB of RAM for light Windows 7 users? Remember, we are talking about the typical implementation that we have seen. That means the desktop image includes antivirus agents, malware agents, monitoring agents and line-of-business applications. These agents and applications add up (especially Line-of-Business apps). Even though the user is a light user, that means they only run 1 or 2 applications. However, those applications are more than Microsoft Word. They are the main Line of Business application. So even though they don’t hit the CPU hard, they still consume a lot RAM (of course these implementations could just put the line of business app on XenApp and not worry about providing a true Windows 7 desktop for light users).

Are you wondering what defines the four groups of users? Here is how we define them:

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.

I’m hopeful that as you start planning your XenDesktop environment, you use realistic approximations on your virtual desktop specifications.

If you want to know more about resource allocation as well as many other areas for planning a XenDesktop environment, then sign up for the XenDesktop Design Handbook. This helps guarantee that you have the latest and greatest design information available.

Daniel – Lead Architect


Windows 7 Optimization Guide for XenDesktop

If you have been following my ongoing commentary regarding Windows 7 optimizations for virtual desktops, you have probably been wondering when all of this information will be put into a document. Well, it has finally happened. Based on many of the items Citrix Consulting has identified, we have our initial Windows 7 optimization guide for virtual desktops using the hosted VM-based VDI model. You noticed that I specified which FlexCast model this is for because if you end up doing local streamed or local VM you might wish to modify certain settings for those use cases.

What you will also see is that other optimization guides probably have many, many more optimizations. Why? Most guides are looking at performance as opposed to the user experience. The settings within this guide are trying to balance the user experience with performance. Some optimizations will make the system run faster without impacting the users while other settings might improve performance might create negative perception. It is a fine line to walk and it is something each person has to determine when building their virtual desktop environment on Windows 7.

If you want the Windows 7 Optimization Guide for XenDesktop, as well as so much more, then access the XenDesktop Design Handbook.

Daniel – Lead Architect

Optimize Your Virtual Desktop Recycle Bin

I’m reading more and more Windows 7 optimization guides for virtual desktops and I’m starting to believe that many people are focusing too much on scalability and too little on the user experience. I’ve spoken about people taking optimizations too far before, but this time I want to talk about one item… the Recycle Bin?

I don’t know about you, but I love the Recycle Bin. Just in case I accidently delete something, I know that I can get it back. But because many different virtual desktop implementations delete modifications upon reboot (Provisioning services included), the general recommendation is to disable this wonder feature of Windows. Think about your desktop experience. Have you ever accidently deleted a file and tried to restore it within a few minutes or hours? I have, and it saved me many times. What if I took this feature away? I don’t know about you but I would be mad as hell.

With Provisioning services, the recycle bin is cleared upon each reboot, but does that mean we shouldn’t allow users to have this functionality within their current desktop session? Unfortunately, the XenConvert optimization utility also disables the recycle bin functionality, but I typically don’t stick to the defaults. I don’t recommend it. I deselect it. And I think if you are really a desktop user and focused on the user experience, you will likely do the same.

Daniel – Lead Architect

Feller’s Law on Virtual Desktop Optimizations

I’ve been spending time developing the Citrix recommendations for Windows 7 optimization and came to an interesting conclusion: many of these settings sounds good, but they don’t really have much impact. I’ve now read two different studies on this:

What have I learned? You will get minimal performance gains IF you optimize while still providing enough usability for users. Also, if you optimize too much you end up destroying the user experience. I posted a comment on the Project VRC’s recommendations to disable Windows Search. It is true that Search does take some resources, but I find search quite useful within my Office applications. For my virtual desktop implementation, if I disable Search, then I can no longer search within Outlook. Others told me their search still works, albeit slower. Why the difference? Because we included different optimization settings within our virtual desktop environment. We did this to try and improve scalability and performance, but now we have another issue… Troubleshooting.

Because we have done different optimizations, some of which are pretty arcane, we now have different effects on the desktop, and not in a good way. So what does this mean? It means the more optimizations you make, the greater the risk for issues and the harder it will be to troubleshoot. This is what I started calling Feller’s Law: “The more tweaks made, the greater risk for issues.”

Does this mean we shouldn’t be doing any optimizations? No, that is just crazy. There are some things we should disable in a desktop virtualization environment. All that I’m saying is that we need to understand what each optimization might do to the user experience, because the user experience will determine success and failure. And making every possible tweak to the environment isn’t really necessary either as many will have limited impact on the infrastructure.

What will you recommend for your virtual desktop environments?

Daniel – Lead Architect

Taking Virtual Desktop Optimization Too Far

I’ve been spending a lot of time focusing on the lessons learned with Windows 7 migration. There are plenty of articles about optimizing the Windows 7 image (I’ve even authored a few of them in my Windows 7 Optimization section). However, I am left to wonder if some of these recommendations go too far.

Most users want to personalize their desktop. They want to configure their own backgrounds. They want to configure their themes. They want desktop sounds to alert them of email messages. So why are we recommending that we disable all of these features?

To save resources. Yes. That is the answer, but is it a good strategy? Disabling this functionality will save some network and system resources but the cost is user acceptance. User acceptance is going to make or break the desktop virtualization solution. You don’t believe me? Look at your own desktop. Did you customize the background? Sounds? Themes? What else? What would you say if you couldn’t do these things?

What would you say if Microsoft or Apple lacked this personalization functionality? They wouldn’t hear the end of it. They would be criticized by every person that touches the OS. So why am I seeing so many Windows 7 optimization guides recommend doing just that?

There is nothing wrong with optimizing the desktop, but these optimizations should not impact the overall acceptance level from our users.

Daniel – Lead Architect

Screen savers and virtual desktops

If a tree falls in the forest and no one’s around, does it make a sound? If a screen saver is running and no one is watching, does it matter? You can debate me on the first question, but the second one is a definite YES.

You remember long ago when fancy screen savers were all the rage? You remember the flying toasters right (if not either I’m too old or you are too young)? What about the fish swimming leisurely across your big (14 inch) CRT monitor? We don’t put as much thought into screen savers as we used to, but they are still there. Most of us simply use the default ones within Windows 7, that is, if we have one at all. But what does the screen saver have to do with virtual desktops? Actually, screen savers have a lot to do with desktop virtualization, especially in the hosted VM-based VDI model (at least if you are trying to optimize your environment). Continue reading Screen savers and virtual desktops

Optimize Windows 7 Visual Effects for Virtual Desktops

Some of you might be aware, others might not.  Did you know that the mouse icon in Windows 7 (and earlier versions) has a shadow?  I bet a bunch of you are looking for it now. It is hard to see, but it is there.  Something that most people wouldn’t recognize as being on or off can have an impact on how much bandwidth is required for a virtual desktop.

Citrix XenDesktop and HDX are smart enough to not send the screen updates for the mouse image to the endpoint, instead they just send coordinates.  Saves a lot of time if you think about how many pixels the mouse takes.  But if you enable the mouse shadow (which is enabled by default), we are talking a different story.  The shadow pixel changes must be sent across the wire because it isn’t just a shadow, it is a blending with the image on the screen.  If you truly are interested in optimizing your Windows 7 desktop virtualization images, then disable the mouse shadow.

It’s pretty easy to do Continue reading Optimize Windows 7 Visual Effects for Virtual Desktops