USB Drive Letter Manager

USB Drive Letter Manager decides which letter a USB drive gets when you plug it in, and it does so from a service that runs before anyone logs on. Plug in the backup drive and it is always X. Plug in the work stick and it is always U. Plug in a card reader with nothing in it and no letter appears at all until a card goes in. The system’s own assignment hands out the next letter it thinks is spare, and this replaces that guess with rules you wrote.

The problem it solves first, without any configuration, is the one that makes drives vanish. The system assigns letters to USB drives before it knows about network shares mapped by the user who is about to log on, so a stick lands on the letter a network drive uses and one of the two disappears from the file manager.

USB Drive Letter Manager checks the mapped shares of the logged-on user and moves the stick to a letter that is really available. Install it, do nothing else, and that particular annoyance stops. Everything beyond that lives in a text file.

Rules in an INI file, and what they can match

There is no settings window in USB Drive Letter Manager. Configuration is a file called USBDLM.INI in the program’s folder, with sections that each list up to nine preferred letters and the conditions a drive must meet to get them. The simplest section names letters and nothing else, so every USB drive takes the first available one from that list. More specific sections match on the drive’s device ID, its volume label, its size, the USB port it is plugged into, the type of connection, the drive type and the user currently logged on.

That is how a rule says the drive labelled BACKUP always mounts as X, anything under 8GB takes K through M, anything larger takes W through Z, and the drive plugged into the front port gets a letter of its own regardless of what it is.

A drive can also carry its own preference, an INI file in its root that names the letter it wants, so a stick asks for the same letter on every machine that runs the service. Letters can be reserved so that local drives never take them, and letters can be excluded outright.

Card readers, balloon tips and mount points

Multi-slot card readers normally claim four letters at once, all empty until a card arrives. A setting removes those letters until media is present and restores them when a card goes in, which clears the clutter from the drive list.

Drives can also be mounted to a folder instead of a letter, so a stick appears as a subfolder of a fixed path and never touches the letter table, which suits a drive that only ever receives wipes from a secure deletion tool before being handed on.

A balloon tip on arrival shows which letter or path the drive landed on, with its size if you want, which sounds trivial and saves the trip to the file manager every time. The service applies every rule at three moments, when a drive is attached, when the service starts and when a user logs on, so a drive already connected at boot ends up where the rules say once the right user is in.

Autorun events for drives you describe

USB Drive Letter Manager autorun sections run a program or script when a drive matching their conditions arrives, so plugging in the backup drive can start the backup and plugging in the camera card can open the photo import.

The conditions are the same set the letter rules use, and the actions run for the logged-on user. It is the mechanism the system’s own autorun used to provide before it was locked down for good reasons, and here it fires only for drives you describe, which is a different proposition from a stick running whatever it carries.

Keeping autorun.inf files off your sticks remains sensible, and a tool that cleans and guards them covers that side.

A question before a new keyboard is trusted

A related USB Drive Letter Manager setting asks before activating a newly attached USB keyboard or network adapter. Devices disguised as flash drives that announce themselves as keyboards and type commands are a known attack, and the prompt turns a silent event into a question you can decline.

Where the INI file stops

There is no interface, and everything in USB Drive Letter Manager is learned from the help file and tested by editing the INI and reconnecting a drive. That is a real barrier for anyone who has never opened a configuration file, and the help is thorough rather than gentle.

Virtual drives from encryption containers, RAM disks and image mounters are outside its reach, so an image mounter that creates its own drives will keep choosing letters on its own. Non-USB drives can be managed when a rule names their bus type or device ID, which is a bonus rather than the main purpose.

Rules that match on port position break when a drive without a serial number moves to a different port, and the help file says so.

Conclusion

USB Drive Letter Manager suits anyone who has lost a network drive to a USB stick, runs backups that expect a fixed letter, or plugs in the same handful of drives daily and wants them where they left them. Once the INI file says what you mean, the service enforces it for every user without anyone needing the privilege to change a letter.

It is the wrong tool for someone who wants a window with tick boxes, and it will not touch the virtual drives that other software creates. Start with the empty install, which fixes the collision problem alone, copy one of the example INI files when you want more, and keep the help file open beside it.