Limit range of drive letters that can be assigned to USB drives?

I have these scripts that I use with some specific external drives, let's say I: and J:. the scripts require that the external drive always have the same letter.

The issue is that if another USB drive was plugged in first, and Windows assigned either I: or J: to this other drive. So when I plug in my specific external drive, it gets a different drive letter and I have to move drive letters around with Administrative tools, Disk Management, before I can run my scripts.

Any way to tell Windows to never give out some drive letters to a random USB drive?

I adopted a different approach for the scripts I have for using specific external drives. I have a batch file, used as a subroutine for others, that accepts a passed argument of drive label and returns the drive letter [it also works the other way around].

I have adjusted this batch file to cope with the case of drives with no label. Its use remains the same - see FindDriveLetter-Label - TenForums.bat [post #36] - TenForums

I set* a meaningful drive label for my backup drives [in your case, your drives I J] and then use my batch file to get the drive letter currently being used by the drive that has that label.
* When I first set up a new drive after purchase, I check that the label has 'taken' by looking at the drive Properties not just at how it is displayed in File explorer because I have, quite surprisingly, found differences recently.

So, my script controlling a backup has these lines when retrieving the drive letter of a drive labelled Fred

Code:

Set /a FredValue=0
Set ThisTest=Fred
Call C:\Tools\IdentifyDrives.bat %ThisTest%
:: If result is a two letter string [a successful result is a letter and a colon], Fred is connected
If "%DriveResult:~2%"=="" (Set /a FredValue=1) & (Call :GetOnWithIt)
GoTo EndFredBackup

- The variable %DriveResult% identifies which drive letter the drive labelled Fred currently has.
- My variable %FredValue% is used in decision points later in the script {e.g. If %FredValue% EQU 0 GoTo EndFredBackup}
- My subroutine :GetOnWithIt is the section of code that runs the backup
{All my scripts are within subfolders of C:\Tools as explained in my post Set up my Tools folder ditty - TenForums}

The batch file doing the assessment is
IdentifyDrives.bat

Code:

:::::::::: Pass drive label or drive letter when calling this script and get back drive letter or drive label ::::::::::
:::::::::: - i.e. pass one, get the other ::::::::::
:::::::::: - The output is the variable DriveResult ::::::::::
:: Initialisation
Set DriveResult=

:: Assess passed argument
:: Remove any quotes
Set ThisPassed=%~1
:: Bail out if no parameter had been passed
If "FFFFFFFF"=="FFFF%ThisPassed%FFFF" GoTo EndIDDrives
:: Remove any colon
Set ThisPassed=%ThisPassed::=%
:: If ThisPassed is a single letter it must be a drive letter and I must want to get the label
If "%ThisPassed:~1%"=="" GoTo GetDriveLabel
:: Otherwise ThisPassed must be a label and I must want to get the drive letter
GoTo GetDriveLetter

:: Passed drive label, get drive letter [including colon]
:GetDriveLetter
for /f "tokens=1,2" %%D in ('wmic volume get DriveLetter^, Label') do Call :CheckLabels %%D %%E
If "%DriveResult%"=="" (Set DriveResult=PassedParameterNotFound) & GoTo EndIDDrives
GoTo EndIDDrives

:CheckLabels
:: Further processing required to avoid labels being misidentified
:: - FredBig, Fred, FredSmall would otherwise all get a hit on finding Fred
:: Check that the found label is an exact match for ThisPassed
If /I "%2"=="%ThisPassed%" Set DriveResult=%1
GoTo :EOF

:: Passed drive letter [including colon], get drive label
:GetDriveLabel
for /f "tokens=2"  %%D in ('wmic volume get DriveLetter^, Label ^| find /I "%ThisPassed%:"') do Set DriveResult=%%D
If "%DriveResult%"=="" (Set DriveResult=PassedParameterNotFound) & GoTo EndIDDrives
GoTo EndIDDrives

:EndIDDrives
Pause at EndIDDrives during testing - DriveResult is %DriveResult%

The code can also cope with passing a drive letter and getting back a drive label but I have yet to find a single example of that being useful.

Denis

I don't understand the colour coding scheme used in TenForums code boxes so here's an imperfect alternative display of the code I posted above.

Colour codes:
blue - comments
mauve - variable processing
brick red - decision processing
green - program flow
light blue - brackets
orange - external commands

Denis

When I customize Windows deployment images, I copy Windows ISO contents to a folder D:\ISO_Files. I can then mount the image, edit it, add answer files and customizations and so on.

When done, I use this simple batch file to copy the customized install files to a USB Flash drive. It looks for an USB Flash drive with label W10-USB, gets its drive letter, formats it giving it the same drive label (W10-USB), and finally copies the contents of folder D:\ISO_Files to that USB drive:

Code:

@ECHO OFF
for /f %%X in ('wmic volume get driveletter^, label ^| find "W10-USB"') do set USBDRIVE=%%X
format %USBDRIVE% /fs:NTFS /v:W10-USB /q
echo.
echo Copying D:\ISO_Files to drive %USBDRIVE%
xcopy D:\ISO_Files\*.* /s /e /q %USBDRIVE% /i /k
echo .
echo D:\ISO_Files copied to USB drive %USBDRIVE%
echo.
pause

I have the batch file saved as CopyToUSB.bat in my %userprofile%\OneDrive\Scripts folder. The batch reads USB drive W10-USB's letter to variable %USBDRIVE%, and uses it in format and xcopy commands. As long as I use the same USB flash drive label (W10USB), I don't have to know its drive letter.



Kari

Kari said:

When I customize Windows deployment images, I copy Windows ISO contents to a folder D:\ISO_Files. I can then mount the image, edit it, add answer files and customizations and so on.

When done, I use this simple batch file to copy the customized install files to a USB Flash drive. It looks for an USB Flash drive with label W10-USB, gets its drive letter, formats it giving it the same drive label (W10-USB), and finally copies the contents of folder D:\ISO_Files to that USB drive:

Code:

@ECHO OFF
for /f %%X in ('wmic volume get driveletter^, label ^| find "W10-USB"') do set USBDRIVE=%%X
format %USBDRIVE% /fs:NTFS /v:W10-USB /q
echo.
echo Copying D:\ISO_Files to drive %USBDRIVE%
xcopy D:\ISO_Files\*.* /s /e /q %USBDRIVE% /i /k
echo .
echo D:\ISO_Files copied to USB drive %USBDRIVE%
echo.
pause

I have the batch file saved as CopyToUSB.bat in my %userprofile%\OneDrive\Scripts folder. The batch reads USB drive W10-USB's letter to variable %USBDRIVE%, and uses it in format and xcopy commands. As long as I use the same USB flash drive label (W10USB), I don't have to know its drive letter.



Kari

Guys,

I'm amazed at the ingenuity in these scripts, but most of my scripts are actually "jobs" in programs like GoodSync and Retrospect. They only work if they find the external drive at the drive letter built into those "jobs." Retrospect in particular, it is very, very particular about drive IDs and drive letters.

I have made unforced user errors ( ) because I plugged in a USB drive and then did some work, without first checking the drive letter that Windows assigned. Those user errors would eliminated if I could map "other" USB drives away from the drive letters I want to reserve.

- - - Updated - - -

Kari said:

When I customize Windows deployment images, I copy Windows ISO contents to a folder D:\ISO_Files. I can then mount the image, edit it, add answer files and customizations and so on.

When done, I use this simple batch file to copy the customized install files to a USB Flash drive. It looks for an USB Flash drive with label W10-USB, gets its drive letter, formats it giving it the same drive label (W10-USB), and finally copies the contents of folder D:\ISO_Files to that USB drive:

Code:

@ECHO OFF
for /f %%X in ('wmic volume get driveletter^, label ^| find "W10-USB"') do set USBDRIVE=%%X
format %USBDRIVE% /fs:NTFS /v:W10-USB /q
echo.
echo Copying D:\ISO_Files to drive %USBDRIVE%
xcopy D:\ISO_Files\*.* /s /e /q %USBDRIVE% /i /k
echo .
echo D:\ISO_Files copied to USB drive %USBDRIVE%
echo.
pause

I have the batch file saved as CopyToUSB.bat in my %userprofile%\OneDrive\Scripts folder. The batch reads USB drive W10-USB's letter to variable %USBDRIVE%, and uses it in format and xcopy commands. As long as I use the same USB flash drive label (W10USB), I don't have to know its drive letter.



Kari

Guys,

I'm amazed at the ingenuity in these scripts, but most of my scripts are actually "jobs" in programs like GoodSync, Beyond Compare, and Retrospect. They only work if they find the external drive at the exact drive letter built into those "jobs."

I have made unforced user errors ( ) because I plugged in a USB drive and then did some work, without first checking the drive letter that Windows assigned. Those user errors would eliminated if I could map "other" USB drives away from the drive letters I want to reserve.

Then it seems to me that your only option is to assign drive letters that will not get used by anything else - assign YZ instead of IJ.

Denis

Try3 said:

Then it seems to me that your only option is to assign drive letters that will not get used by anything else - assign YZ instead of IJ.

Denis

I was hoping that would not be the answer, but what is, is. Even with this approach, I have 4 different external USB drives that are part of these scripts, so I would still have the issue of matching the drive to a specific letter.

I wish there was some way to submit a feature request to Microsoft.

If you assign them [once only] to WXYZ using Disk mgmt {C:\Windows\System32\diskmgmt.msc} or something like MiniTool Partition Wizard then they will retain those drive letters when they are re-connected unless
- you first connect 19+ other drives at the same time as your desired drives so that the computer is forced to re-use W then X then Y then Z
- you do a Windows 10 Version update - drive assignments do need to be checked afterwards [but this has only messed up drive assignments a couple of times].
- [added 14 Sep 2019] - some Cumulative updates can mess up drive letter assignments as well. KB4515384 does so on one of my computers [but not on the others].

You could use the Feedback hub to suggest that change but, as explained, I think Windows can already achieve what you want without any change being necessary.

Denis

Denis,

Thanks. After re-reading your previous message, I think that I can mark this thread SOLVED.

Appreciated.