2 removable drives - no drive letter assigned when connected

Posted on 2005-04-23
Last Modified: 2010-04-03
I have 2 maxtor USB drives that im trying to connect to a Win2k3 server. Only 1 drive will be connected at any time (swapped out for backups - 1 off-site one connected). The next drive letter available to windows (with no removable drives connected) is the G drive. I have my backup software backing up to the g drive, so when i plug in either external drive i want them to be assigned G: .
This however does not work. One retains G: - i unplug then plug in the second drive and it does not show up. I got into disk management and the drive is there but it is not assigned a drive letter. So i assign it G:. Then i unplug and plug it back in and once again it has no drive letter. Any ideas what is going on?
Question by:stephen15c
    LVL 6

    Expert Comment

    stephen15c: newer versions of Windows 'remember' the drives attached to the system. A unique ID is generated for each drive and saved in the Windows registry as well in the master boot record of the drive. With DOS based Windows you could always attach any drive and it would get the next available drive letter, but this is no longer possible.
    Hope this helps you understanding what is happening, sorry that I do not have a solution for you.

    LVL 13

    Accepted Solution

    Hello.  Before you remove the USB drive, do you double click the Safely Remove Hardware icon in the system tray?
    If so, that might be the end of your issue.

    If not, there is a way around it.  Do not leave any of your drives assigned to G:.
    Insert a drive and assign another drive letter to it; let's say X: for an example.  The next time you plug it in, it will be X:.
    Insert a drive and assign another drive letter to it; let's say Y: for an example.  The next time you plug it in, it will be Y:.

    Open Notepad and type:
         subst g: /D                             This line deletes the previous G: substitute mapping
         subst G: X:\                            This line attempts to create a G: drive that's really an X: drive   (If it fails, it will go to the next line)
         subst G: Y:\                             This line attempts to create a G: drive that's really a Y: drive    (If the G: drive had been mapped, this line will fail)
    File --> Save As "C:\USBmap.bat"
    Use the quotations to ensure the file is saved as a batch file.
    You can add as many drives as you want.  The only time the mapping will succeed is when a drive with the appropriate letter exists.

    If your backup software has pre- commands, simply have the backup software execute the batch file before backing up.
    If you're using Windows backup, in Task Sceduler simply schedule the batch file to run before the backup.
    LVL 95

    Expert Comment

    by:Lee W, MVP
    What backup software are you using?

    I have a script using NTBackup for my systems that looks for a marker file and when found, sets the backup drive to that drive letter.  Works quite well for me.
    LVL 13

    Expert Comment


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