Citrix Personal vDisk, a registry key break down

While preparing for the 1Y1-200 and 1Y1-300 exams based on the Exam Preparation Guides released by Citrix I realized that my knowledge of the Personal vDisk was a little bit rusty as I don’t use Personal vDisk (PvD) that often.

 

After reading the eDocs I noticed that not all possible registry keys were mentioned so I wanted to do a break down on the registry keys for the Citrix Personal vDisk.

Personal vDisks provide separation of data en personalized settings by redirecting changes made on the user’s VM to a separate disk. The PvD is blended to the VM so the user won’t notice the addition of the PvD and thus delivering the same experience as on an oldschool fat client. From the eDocs on Personal vDisks in XenDesktop 7:

Personal vDisks have two parts, which are by default equally sized:

  • One part comprises C:\Users (in Windows 7) or C:\Documents and Settings (in Windows XP). This contains user data, documents, and the user profile. By default this uses drive P: but you can choose a different drive letter when you use Studio to create a machine catalog with Personal vDisks.
  • The other part comprises a Virtual Hard Disk file (a .vhd file). This contains all other items, for example applications installed in C:\Program Files. This part is hidden from users; it is not displayed in Windows Explorer.

Personal vDisks support the provisioning of department-level applications, as well as applications downloaded and installed by users, including those that require drivers, databases, and PC management software. If a user’s change conflicts with an administrator’s change, a Personal vDisk provides a simple and automatic way to reconcile the changes.

When searching on information about the PvD registry keys I came across this screenshot from, apparently, an older version of PvD:

citrix personal vdisk

Moving forward I found the following keys in the different eDocs and knowledge base articles.

Key : HKEY_LOCAL_MACHINE\Software\Citrix\personal vDisk\Config

AutoActivate REG_DWORD Enables the automatic activation of the PvD
BlockLogonIfUpdateInProgres REG_DWORD Blocks logon while an update to the vDisk is in progress when set to 1
EnableUserProfileRedirection REG_DWORD This value ensures that all of the space on P: is allocated to applications
HideVHDMountPoint REG_DWORD This hides the VDIMountPoint from the explorer view
InterceptShutdown REG_DWORD Educated guess: This value is for the inventory reminder when updating a PvD inventory and you’re shutting down the VM
MachineId REG_SZ The machine ID (hostname)
 PercentOfPvDForApps REG_DWORD This sets the default allocation of space on the personal vDisk
PowerOffAfterUpdate REG_DWORD Educated guess: This will power off the machien after an update of the inventory
PvDResetUserGroup REG_SZ  To enable other users to reset personal vDisks, add these users to an Active Directory security group, then add this security group to the PvDResetUserGroup registry key on the desktop machine.
UserDiskDrive REG_SZ This sets the drive for the PvD
VdiEnvironment REG_DWORD Determines if the device is part of a VDI environment
 VHDMountPoint REG_SZ This value sets the VHD Mount point

I found a couple of the reg keys just from the documentation but it got me wondering if they documented everything. So with the great help from Andrew Morgan who opened up his lab for me I got a Windows 8 desktop with PvD up and running within minutes and took the following screenshot:

In this newer version of PvD (7.x) there are a couple more registry keys available:

MinimumVHDSizeMB REG_DWORD To set the desired new initial size of the VHD (in megabytes
PvDReservedSpaceMB REG_DWORD To Set the size of reserved space in MD for PvD
EnableDynamicResizeOfAppContainer REG_DWORD This value enabled/disables dynamic resizing algorithm
InventoryVersionMinor REG_DWORD User defined minor release number
InventoryVersionMajor REG_DWORD User defined major release number

I hope this article helps you understand the available keys in the Citrix Personal vDisk. If you have an addition to this list please leave a comment, I would also love to hear about your thoughts about the educated guesses I did on the registry keys that were missing in the documentation.

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Kees Baggerman

Kees Baggerman is a Staff Solutions Architect for End User Computing at Nutanix. Kees has driven numerous Microsoft and Citrix, and RES infrastructures functional/technical designs, migrations, implementations engagements over the years.

3 comments

  1. Paul Stansel says:

    Thanks Kees. I took 400 and was surprised how LITTLE there was about PVD on there.

  2. Renan says:

    What is the real impact on having this: MinimumVHDSizeMB set to, let’s say: 100MB ? And if it is set to a big value (let’s say 5GB) would it take longer to grow?

  3. Rikesh says:

    Hi

    I am struggling with any reg modifications to get my PvD 20GB allocation just for apps. We use UPM and will move to Appsense later so do not want user profile redirection to pvd. I also need to use P: to X:

    When I try set the keys it gives my pvd 20gb but it says only 20MB left!!? Not sure why the space is consumed! Please can you help!

    Windows 7 VDA 7.6

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