PVDisk – free space on disk doesn’t reflect space used

Hi all,
I recently deployed VDI in a Box for a customer who ask me this question : “We set up 60GB per PVDisk in VDI manager but we only see 30GB free on the p:\ drive of the deployed desktops. Why ?”. It is absolutely normal and configurable. Note that article apply for VDI in a Box or XenDesktop (Desktop OS).

When you connect to a new published desktop equiped with PVDisk (without any user data) and browse the PVDisk (P:\ by default), you can see that there is only 50% of free space. If you uncheck the hide system protected files option in Folder and search options, you’ll see that there is a big file in P:\ consuming almost all used space.
This is completely normal. PVDisk allows users to store files in P:\ (user data) and to install applications or change configurations. Applications are typically installed in C:\Program Files. But, when PVDisk is implemented, writings made on C:\ are hooked and stored in the hidden special file.
By default, a 60GB PVDisk allows 30GB of writings in C:\ (apps and config) and 30B of user data (in P:\users). The 50% space is allocated even if no writings are made in C:\.
You can change this 50-50 distribution by editing your master image and editting the following registry key which sets the percentage of PVDisk space allowed for system changes (application installations, etc.) :

HKLM\Software\Citrix\Personal vDisk\Config\PercentOfPvDForApps

Of course, once this setting is updated, you have to update the previously deployed desktops with the updated master image.

Thanks for reading.
Jerome.