App-V Hidden Drive Letter ADM File

In our environment, our users love their drive letters, and they do so to the Nth degree. As part of a change control process, myself and a colleague have scheduled the deployment of the App-V Client across our business estate to allow us to begin provding the users with user-centric real-time streamed applications to meet their business needs.

We today discovered the true nature of our Nth degree network drive letter because after some review, it became aparent that not a single letter (beyond the usual C, D, E for local disks) was free for company-wide use which caused us pain on the inside. We came to the conslucsion that people in our business very rarely use floppy disk drives anymore, and even less people (zero to my best guess) use a second floppy disk drive, which means that the B: drive would be available across the estate.

Using the Microsoft App-V ADM file for Group Policy (available for download from, I re-configured our GPO to force the clients to use the B: drive instead of the App-V default Q: drive. I tested the configuration change on my own machine (ICT dogfooding for everyone), and also streamed a couple of applications to verify the drive letter change didn’t cause any issues, and I came to an idea. If the App-V virtual file system is inaccessible by the user because of the ACLs that App-V applies to it, and because the user has no reason to be meddling in the App-V virtual file system drive, why, display it to them?

I took a look at the Windows Explorer, Hide these specified drives in My Computer policy in the User Configuration portion of Group Policy however for reasons beyond me, Microsoft only gave you a very limited set of options in this policy (Hide A, Hide A and B, Hide A, B and C, or Hide All Drives). This policy was probably useful in the legacy days where you only wanted to restrict use of local floppy disk drives, however it’s not very useful in the 21st century.

The way around this, is to build your own custom ADM file to change the options for disabling the drive letters.

I have this evening created a custom ADM file for such a purpose, and in my example, the file is crafted to allow you to hide the B drive, or no drives, however you can add as many options to this file as you like.

How you configure the file to restrict particular drives is based on a binary value using a reverse alphabet table. Details for calculating this can be found on the Microsoft Support article Using Group Policy to Hide Specific Drives ( If you aren’t ocomfortable trying to do this in your head, you can simply copy and paste the table out of the article into Notepad and do your working in there.

Simply add the ADM file to an existing GPO and link it to an OU which contains users in AD, and you’re all set.

If you want to only restrict a single letter, then you can simply edit my file by modifying the label for, and the binary value for the BOnly item. The file is shared and free for you to download from my Windows Live SkyDrive account. I’m also happy to take comments or answer emails with questions about how to modify the file.

App-V Client Management via GPO

Deploying the App-V Client to end-user machines can be headache. Microsoft provide ADM files for managing the configuration of the App-V Client via Group Policy in AD DS, however if you are trying to deploy the client yourself, you will soon discover that the Microsoft ADM files don’t allow you to configure an App-V Publishing Server. The only options you have with the ADM files are to override the sequenced application package and icon source roots.

Using this method, you install string for silent installation will look something like this:


As anyone can see this isn’t exactly elegant, and if you are using SCCM to deploy the App-V Client as I am, you will soon discover SCCM has a character limit for the installer path which means you may have to turn to building a batch file to execute the installation and then call the file in the SCCM Program.

The other problem you will have are that you are then hardcoded to use the server name and port specified in the install. Yes, you could use a DNS CNAME to direct your clients to the App-V servers, and sure you can use a GPO to edit the registry keys on the end-user machines after the fact, however none of this is elegant as properly managing the deployment.

Introducing Login Consultants, a Netherlands based virtualization specialist company. This company provide a third-party ADM file for you to import into AD DS for extending the management options for App-V from the Microsoft ADM file, and best of all, you can register and download the ADM file for free from

Using the Microsoft ADM file and the Login Consultants ADM file in conjunction, your install string turns into this:

setup.exe /s /v” /qn”

Much cleaner, easier to setup in Configuration Manager and then it gives you the ability to manage all of your App-V server configuration, including server name, ports, protocol, SFT_SOFTGRIDSERVER environment variable and all the other settings you need via Group Policy.

For centralising and streamlining management, this is a huge boon, as it means you have a one size fits all deployment of the App-V Client and then allowing you to manage everything else from either AD DS or from the App-V Management Server.