The best choice of deploying vDisks in your Citrix Provisioning Services Environment is taking advantage of the “Dynamic Mode”, but if you are stuck with some vDisks in Fixed mode, you could use the VHD Resizer tool together with either the built in “Windows Disk Management” or “Citrix Provisioning Services” to expand those…

To start with, make sure you have a fresh copy of the vDisk in question (.VHD and .PVP files)
Attention: Do not resize the one being used in your production environment.

1. Download VhdResizer (This software requires .NET Framework version 2.0.50727)
 Start the software and select the source vhd file (your copy of the vDisk), the destination and the new size you would like to assign.
Now, you do have a couple of options on how to proceed:

1.1. Import the resized vDisk into your Provisioning Services Environment, Boot the vDisk in Private Mode, and extend the partition.
When you are done with this, you could boot your newly rezied vDisk in “Production – Read” mode…
1.2. Proceed with the steps below if you prefer to complete the whole procedure on same VM as you are already logged on to…

2. If you chose to proceed with step (1.2), Open Computer Management from Start – “Administrative Tools” and expand Storage to access “Disk Management”

3. Right click Disk Management, select Attach VHD, browse to the VHD file you already expanded, and click OK
4. Right click the imported VHD and select Extended Volume
5. Click Next on the Welcome to the Extend Volume Wizard screen
6. On the Select Disks screen, Enter the amount of space you want to extend the drive to, and click Next
7. Click Finish on the Completing the Extend Volume Wizard
8. Now you should see the VHD extended to a larger size
9. Right click on the VHD to detach it, and select Detach VHD
10. On the Detach Virtual Hard Disk prompt, click “OK” and make sure “Delete the virtual hard disk” after removing the disk is not selected.
11. Import the vDisk into your Provisioning Services infrastructure and you should be good to go…
12. Boot the vDisk to make sure the Operating System sees the new size.