Personal vDisks – Part 3

Hello and welcome to Personal vDisks – Part 3!  Wow, it’s been a while since I last posted!  Hopefully, you’ve read Parts 1 and 2 and found them useful in explaining the practical sides of the new Citrix Personal vDisks and what to expect when implementing it.

Just to recap, Part 1 covered an introduction into what a PvD is and where it can be used within your XenDesktop environment and Part 2 covered how to configure and initially setup XenDesktops with PvDs.

Now, in Part 3, we are going to (hopefully) dive deeper into what I’ve discovered from installing PvD’s in my test lab (if you haven’t already!  I was hoping to get this out about 6-7 weeks ago whilst this was still super new stuff!)

As you can see from the screenshot below, I have allocated a 10GB PvD and it is showing as 50% full.  This is because, by default, when you create a PvD, it is created equal parts User and Applications.  Also, by default, the User disk (Personal Disk) is given drive letter P: (more about this later). 

XenDesktop with PvD attached

By looking at the hidden files within the Personal Disk (PvD), you can see the following files and that the User Application portion of the disk has been marked out for use by the UserData.vhd.thick_provision file. 

Hidden files within the PvD

As far as I can tell, this is static so once you fill up this User application area, it will not grow it size.  You can also see the UserData.vhd which is the actual user apps area.  Now, this is thin provisioned and will grow as you install user apps so the only reason I can think for having the .thick_provision part is to mark out the area of the drive that has been set aside for user apps so that the User Profile section, and I suppose the User apps section doesn’t grow beyond its means and start taking space from the other partition.  So, point number one – the size of the User and Profile partitions are static, not dynamic.

Now, if you have, say a 20GB PvD, you will not necessarily want 50% of this for User Data as you may be using Roaming Profiles (why?!?), Citrix User Profile Management (:)) or another Profile Management system such as AppSense Environment Manager.  So, having 10GB of space for user data which is redirected anyway is a waste of this space as in theory, the user will never save to it.  No problems.  We can change the default values by editing the Registry – and before you ask, yes, this is the recommended (and only) way of doing this.

In order to change the default behaviour by amending the following registry entry:

[HKLM\Software\Citrix\personal vDisk\Config]


All of the registry side of the PvD are held in this key.  See below for the possible values you can change.

PvD Registry settings

As you can see, I have changed the value to 90 (%).  As always, a reboot is required for the change to take effect.

Once rebooted, you can now see that the disk is showing as low disk space because 90% has been fat provisioned as User Application space.

PvD with 90% dedicated to apps

Now, you may ask “why have this user space when I using UPM/AppSense and redirecting user’s folders to their home drive?”.  Well, it just gives you a “free” way of having user personalisation without having to do anything.  With the User Data selection, any changes the user makes to the VM, i.e. saves data to “My Documents”, adds icons to Start Menu and changes the Desktop, are redirected to the PvD and saved.  This means that after a reboot the O/S image will revert back to the clean PVS image but user personalisation will be persisted without having to install another product.  There is nothing to say that you can’t redirect user data and still use the built-in personalisation of the PvD.  It is a way of allowing Personalisation for smaller environments where you do not want the added complexity (or possible expense) of having an additional product.

Remember that the main goal of using PvD is to allow users to install their only applications.  You are giving the users a Private Desktop but utilising all the benefits of a single, gold PVS streamed image.  Less maintenance and easy to update all of your Private Desktops within your estate.

To see this built-in Personalisation, navigate to the newly created P:\ drive and you will see a Users folder.  This is just the C:\Users folder redirected, which is dynamic in the sense that you can disable this feature if you wish to use UPM, AppSense or another Profile Management system. 

P Drive

By changing the value of EnableUserProfileRedirection from 1 to 0, you will turn off the built in Profile Management of the PvD and can use whatever you like.  Oh, by the way, Citrix have stated that if you are using Citrix User Profile Management then this will automatically be detected and (I imagine) changes this value for you or has some other integration unbeknownst to us at this stage.  You do have to use the latest version of UPM though, which is 4.1 (at time of initial writing).

Anyway, back to EnableUserProfileRedirection=0.  As you see from the below screenshot, I have disabled User Profile Redirection on my PvD and if you go into P:\Users you will notice that the user folder is no longer there but back in its original location of C:\Users.

Profile Redirection disabled

Now, it is important to note that these changes should be made before any users have logged into their desktops and had a PvD assigned to them.  If you already have users that have logged into their desktops with PvDs before you have disabled profile redirection, changing the registry value of EnableUserProfileRedirection from 1 to 0 will have no effect.

In order to disable Profile Redirection in this case, you will need a different approach.  I will document this in a following blog article.

Another thing I have noticed is with the “PercentOfPvDForApps” value.  If you edit this after a user has logged in to change the ration of apps v. user area, then it changes without issue.  So, the above example, I changed it from 50/50 split to 90/10 in favour of apps.  If you then try to change it again, say, back to 50/50, this change will not take effect.  I believe that once you have increased the size of the UserData.vhd.thick_provision file, you cannot shrink it as this is a fixed, thick provisioned partition.  Although I haven’t tested this fully, I imagine you can increase the size if you want.

To decrease the size of the User Data partition, you would first have to change the registry setting of PercentOfPvDForApps to the desired value in the base image and update the PvD Inventory (see Part 2 of my blog for this) and then either reset the PvD from the Desktop Director console or run the following command from elevated command prompt on the VM:

“C:\Program Files\citrix\personal vdisk\bin\ctxpvd –s reset”

This would reset all User Data excluding Profile information, so in effect, a user would lose any applications installed. 

So, there we have, hopefully a better understanding of Citrix’s Personal vDisks and how you can use them in your environment to replace the traditional “static” Private desktops and utilise single image management with a fully user customisable desktop.

Keep an eye out on my blog for more PvD stuff as I explore further and hopefully have plenty of opportunities to install this for customers in the future.

Thanks for reading and hope this was helpful.


10 thoughts on “Personal vDisks – Part 3

  1. Vincent says:

    Did you every blog about how to disable folder redirection? I am running into the same issue as you described when the reg setting isn’t enough.

    • Hi Vincent,

      Thanks for reading the article. No, I haven’t yet as I’ve been busy but the other day I did get a reply from one of my contacts from Citrix who explained the reason for this.

      With the PvD, you have your C:\ drive which is your PVS base image for the machine and is read-only. Then, on top of that you have a hidden V:\ drive which is a base image for the machine PLUS the changes made by the user to the drive which is read-Write. Then on top of that, you have the P:\ drive which contains the user personalisations which is read-write.

      When you enable the registry key to stop storing the user information HKLM\Software\Citrix\personal vDisk\Config\EnableUserProfileRedirection this only disables the storing of this information on the P:\ drive. However, as profile information is still written to the C:\ drive which is Read-Only and all writes are

        redirected to the V:\ drive

      therefore it gets stuck into the PvD when using a standard windows profile. Standard windows folders are stored on C:\users which will be redirected to V:\users.

      You can confirm this is the case by resetting the PvD on the master image it should clear the profile settings from the V: drive.

      The registry key is designed to be used in conjunction with a Profile Management solution delete profile on logoff action so what happens is your profile is cached locally and deleted on logoff. But if you just enable the key without a profile management solution then the profile has to be written somewhere and it gets written to the V: drive

      Does this make sense? Essentially, it’s by design as this registry key is meant to be used with a Profile Management tool such as Citrix Profile Management, AppSense Environment Manager or RES Workspace Manager. I suppose, even with Roaming Profiles as well as Microsoft do claim this is a Profile Management solution.

      I intend on testing this with Citrix Profile Management with folder redirection and AppSense Environment Manager in the near future.

      What profile solutions were you using? Roaming Profs? Mandatory etc.? I hope all this makes sense as effectively C:\ drive gets redirected to P:\ until you switch off profile redirection and then C:\ gets redirected to V:\ (which is still on the PvD).

      Stay tuned for more ramblings about Citrix, PvDs and more and thanks for reading.


      • Vincent says:

        Yes, it makes sense thank you (sort of). We made the change and still saw that the profile was being written to the P drive. However, it was found that an admin made a change to the UPM registry inclusion. From what I understand it was only looking at these settings and nothing else. So if that is the case, it would default to PvD default of writting profiles which would be the P.

        One more thing I don’t understand is how PvD works withouth making the reg change in the first place. I read your article that states it autodeteckts it, which I am assuming is the answer…..strange

  2. Vincent says:

    The other point I didn’t get was “You can confirm this is the case by resetting the PvD on the master image it should clear the profile settings from the V: drive.

  3. Hi Vincent,

    So first off, I’ve now tested with AppSense Environment Manager and Citrix Profile Manager and it appears that these and/or XenDesktop does not automatically change the registry setting:

    HKLM\Software\Citrix\personal vDisk\Config
    EnableUserProfileRedirection = 0/1

    This is a manual step so don’t forget to check it before using a profile management tool.

    Secondly, to explain about resetting a PvD, there are two ways to do this which will delete any applications/user data installed and reset settings back to default, so if you’ve changed the ratio of apps to user data to 80/20, it will revert back to 50/50.

    There’s the command prompt way:
    “C:\Program Files\citrix\personal vdisk\bin\ctxpvd –s reset”

    or the Desktop Director way – launch DD, drill down to the specific PvD desktop and select the option “Reset Personal vDisk“.

      • Hi Charles,

        Comparing CPM and AppSense is a hard question as AppSense is much more than a User Profile tool. Even if you are just talking about AppSense Environment Manager, again, it is so much more than just pure User Profile Management as you can replace all your Group Policy and Login scripts if you so wish. It’s very customisable and has good features like allowing you to have certain actions happen at application/process start which can increase login times as you are not having to map drives, create printers and load Application ADMX files at login but rather when they are needed. It also has User Personalisation that captures all changes to the user profile and sticks them in a SQL database allowing you to use a fixed Mandatory profile (meaning quicker login times) but allowing users to customise the look and feel of their apps and desktop. Saying this, Citrix UPM does allow quite a bit of personalisation to be captured and streamed into the profile on demand, rather than at logon.

        It very much depends on what you are looking for. Citrix Profile Management along with Group Policy and Group Policy Preference can achieve most of what AppSense Environment Manager can (or at least the Policy and Profile side) and as just a profile solution is less complex. Also, with Profile Management covered under XenDesktop Enterprise and Platinum licenses, and Group Policy built in to Windows, using this would be a lot cheaper than using AppSense for just profile management. But on the flip side, with AppSense, you also get Application Manager and Performance Manager. Using all the AppSense products together can make for a slick and well performing user environment but it does add complexity and require knowledge of the product suite. But it does allow you better control and as mentioned before, the ability to load parts of the user profile and/or settings “on demand”.

        A tough question and not easily answered 🙂 In my role, I have to be agnostic to the technology so my advice to you would be test them both and see which one you prefer and what does the job you want it to do best. Never rule out the cheap/free alternative because it isn’t as “feature-rich” as the top selling product but don’t just go for something because it’s got every gizmo under the sun. Test all options and see what fits best. Also, don’t forget RES with Workspace Manager and Automation Manager. Two very good tools which are GUI based and easy to use. RES Workspace Manager is RES’ user profile management solution and has come a long way in the last few years. There are others but these are the main three products I work with when it comes to User Profile Management.

        Sorry if this has turned into a bit of a read and hasn’t answered your question but as I said, it very much depends on your environment and what you are looking to achieve.

        Thanks for reading,


  4. Cory says:

    Just wondering how long a personal vdisk master image update should take. For instance, I make a new version on the PVS server and launch my master image in maintenance mode. For example, I repair Office 2013. Then I run the Update Personal vDisk Inventory and shutdown the master image. I promote the new version into production. I reboot a user’s VM. It boots fine but never registers in the DDC. I finally get impatient and login at the xencenter console as admin to that user’s VM. It immediately pops up a window that says “Desktop Update in Progress”. That progress bar sits there for 30+ minutes before shutting down the VM. When I bring it back up it is registered in the DDC. Is this normal behavior. How long should a simple update to the master image take before your VM’s are ready for production again?

    • Hi Cory,

      It depends on a number of factors regarding your environment such as where the PvD is located (storage-wise), the size of the PvD, the change made to the PvD etc. but I would say that if it does successfully complete, then I don’t think this is a problem. As to the VM not registering with the Controller, I’m not sure without looking into this but it could be by design as the disk isn’t ready until the PvD has fully updated so this could be done as a precautionary method so that the user cannot log on until it is completed.

      If it is of concern, have a look at any hotfixes available for PvD or see if there is a update available that might list what you’re seeing as an issue fixed.



  5. Cory says:

    Another question for you. Is there a way to see what’s inside UserData.V2.vhd.thick_provision? I noticed you mentioned above that it shouldn’t grow in size, but mine are growing exponentionally. For instance, I started with a 20GB PVD split 50/50. Now that user has a 23GB PVD split 50/50 but the Apps portion keeps mocing to 100% and then the whole thing grows again just a little bit. I’m getting this info from the Desktop Director. Also, are you willing to consult?

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