Getting Started



Getting started


USBDLM is a Windows service that gives control over Window's drive letter assignment. Initially made for USB drives it can now control drive letters of other drive types too.

Running as service makes it independent of the logged on user's privileges, so there is no need to give the users the privilege to change drive letters.

It automatically solves conflicts between USB drives and network or subst drives of the currently logged on user.

Furthermore you can define new default letters for USB drives, reserve drive letters and much more.


It can deal with non USB drives too when a BusType or DeviceID configured.


USBDLM works with XP, Vista, Windows 7, 8, 8.1, 10 and all the Windows Server versions. The x64 version works on x64 editions of Windows only.

Windows 2000 support has been dropped with V4.8.


It is primarily tested under


  • Windows XP SP3
  • Windows 7 x64
  • Windows 10



USBDLM is not compatible with Microsoft Multipoint Server clients.





USBDLM does not come with a SETUP.EXE, it's all manual work. See Section Installation.

An MSI is available which installs to %ProgramFiles%\USBDLM. And you can build your own MSI.





The software is not limited or crippled in any way. It's fully functional without a time limit. There is no "full version".


USBDLM is Freeware for private and educational use only. Otherwise a licence is required per computer after a 30 day test period.

"Educational" means institutions where the students outnumber the employees.

Furthermore it's free for public, free of charge libraries.


Price list is available here:


Licence agreement





When a drive (e.g. a USB flash drive) is attached for the first time, Windows mounts it to the first available drive letter. The drive letter can be changed in the Windows Disk Management console, but Windows can save only one drive letter per drive and vice versa. So, you cannot have more than one drive on a high drive letter in succession.


With USBDLM you can


  • check if the letter is used by a network share of the currently logged on user and assign the next letter that is really available (no configuration required)
  • reserve letters, so they are not used for local drives
  • assign a letter from a list of new default letters, also dependent on many different criteria as the active user, drive type, type of connection (USB, FireWire), USB port, volume label, size, user and others
  • let remove the drive letters of card readers as long as there is no media present
  • ask the user for a password before he can use a drive
  • let show an balloontip on drive arrival which shows the assigned drive letter
  • run something on click on the balloontip
  • executing an autorun, also depending on the criterions mentioned above
  • and much more...


All functions are applied to USB drives at the moment they are being attached, when the USBDLM service starts up and when a user logs on.


Instead of letters you can set up empty folders on NTFS drives as mount points too but this brings some limitations and problems, see configuration.