Warning: Disabling automount can cause failover clusters to fail the storage portion of the Validate a Configuration Wizard.
To prevent Windows from automatically assigning a drive letter:
1. Create a .txt file on a share.
2. Inside the text file put the words "automount disable".
3. Create an Application Launcher element with the following settings:
File name including path = Diskpart.exe
Arguments = /s \\SERVERNAME\SHARE\TXTFILE.txt (Change the UNC path as needed)
Miscellaneous Options = Run as administrator
4. Configure the Validation Logic accordingly and Save.