USBDLM is a Windows service that gives control over Window's drive letter assignment for USB drives. 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.

USBDLM is a Windows service that gives control over Window's drive letter assignment for USB drives. 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.

When a removable drive (USB flash drive, flash card reader, portable hard drive) is attached for the first time, Windows mounts it to the first available 'local' drive letter. If there is a network share on this letter, Windows XP will use it anyway for the new USB drive because since XP network shares are specific to the current user and not visible in the context of the system where the letter is assigned. The USB drive then appears to be invisible. This is fixed by SP3 in most situations.

You can change the letter assignments in the Windows Disk Management Console with a lot of mouse clicks but you have to do it again for every new device.

And, for USB devices that have no serial number (in violation of the USB standards) you have to do it too when you attach it to a different USB port.

USBDLM can for newly attached USB drives
1. 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
2. reserve letters, so they are not used for local drives
3. assign a letter from a list of new default letters, also dependent on many different criteria as the active user, drive type, connection (USB, FireWire), USB port, volume label, size and others
4. assign letters for a specific USB drive by putting an INI file on the drive
5. remove the drive letters of card readers until a card is inserted
6. show a balloon tip with the assigned drive letter(s)
7. define autorun events depending on many different criteria

USBDLM works with Windows 2000, XP, Server 2003, Vista, Windows 7 and Server 2008. The x64 version works on x64 editions of Windows only.

1. Installation
Unzip the distribution file (USBDLM.ZIP), e.g. to your programs folder (a USBDLM folder is included). On NTFS formatted drives this requires admin privileges.
As result the files should be in a folder like C:\Program Files\USBDLM

Under Vista and Windows 7 I suggest to install USBDLM in a different folder than C:\Program Files, because under this folder changes of the USBDLM.INI made by a non elevated user are redirected into the "Vista Virtual Store" where USBDLM will not read it.
In a folder like C:\Tools\USBDLM there is no problem.

USBDLM will not run from a network or subst drive, it must be located on a "real" local drive.

Then enter your prefered configuration into the USBDLM.INI (see below). There is a sample file included called USBDLM_sample.INI. Either create a new USBDLM.INI or rename the sample file. On an NTFS formatted drive editing the USBDLM.INI requires admin privileges. Under Vista you should start the Editor elevated, otherwise the USBDLM.INI might be redirected into the Vista virtual store where it has no effect.

If you are logged on with administrator privileges you can simply install the USBDLM service.
_install.cmd

This does not copy any files, it only registers USBDLM as service and starts the service. Without administrator privileges you will be asked for.

Once installed USBDLM is permanently running as Windows service. The service starts automatically on Windows startup.
Remember: Once installed as service it does not matter from where the service is started. The USBDLM.EXE is loaded from the folder where the _install.cmd had been started from!

2. Uninstallation:
You can uninstall the service using parameter -uninstall, this is waht the _uninstall.cmd does:
_uninstall.cmd

This stops the service and unregisters it. Installation and uninstallation can be done without the message box by using
USBDLM -silentinstall
USBDLM -silentuninstall

It returns Errorlevel 0 on success, 1 on failure. You can stop and start the installed service by means of the NET command:
net stop USBDLM
net start USBDLM

or by means of the _stop and _start command script which are using the USBDLM.EXE and request admin previleges if required. You can change the drive letter settings in the USBDLM.INI without restarting the service because it's checked for changes each time a drive event occurs.

The license of this software is Freeware, you can free download and free use this system utility software.