External Drives and "fooling" the OS Can you make it seem like two external drives, whne swapped out have the same drive letter for backup

Posted on 2005-04-27
Last Modified: 2010-04-03
I have a Windows 2003 Dell Server with Raid.

In past installations we were able to have 2 WD external drives. Swapping them out on the same USB connection on a weekly basis to keep 1 Ext drive with the the previous weeks backups off site.  On this installation every time I swap the drives, the one currently plugged in is F drive and when I swap it out, the OS knows as when I plug it assigns G to the swapped drive.

As the backups are set to go to F....this will not work.

We have this working on other systems. What am I missing. I formatted the 2nd drive and it is clean.

Any other suggestions to end up with the same result are welcome. We are using Windows Backup.
Question by:tvacc
    LVL 95

    Expert Comment

    by:Lee W, MVP
    I do similarly, though when I set the drive letter, it usually sticks, F: for me as well.  Nevertheless, one work around is to put a simple text file on the drive, say "backup.txt".  Then copy the command line of the scheduled task you use for backup and put it in a batch file.  The batch file would look something like this:

    Rem Check for the backup drive
    If Exist F:\backup.txt SET BackupDrive=F:
    If Exist G:\backup.txt SET BackupDrive=G:
    If Exist H:\backup.txt SET BackupDrive=H:
    If Exist I:\backup.txt SET BackupDrive=I:
    If Exist J:\backup.txt SET BackupDrive=J:
    If Exist K:\backup.txt SET BackupDrive=K:
    If Exist L:\backup.txt SET BackupDrive=L:
    If Exist M:\backup.txt SET BackupDrive=M:
    If Exist N:\backup.txt SET BackupDrive=N:
    If Exist O:\backup.txt SET BackupDrive=O:
    If Exist P:\backup.txt SET BackupDrive=P:
    If Exist Q:\backup.txt SET BackupDrive=Q:
    If Exist T:\backup.txt SET BackupDrive=T:
    If Exist U:\backup.txt SET BackupDrive=U:
    If Exist W:\backup.txt SET BackupDrive=W:
    If Exist X:\backup.txt SET BackupDrive=X:
    If Exist Y:\backup.txt SET BackupDrive=Y:
    If Exist Z:\backup.txt SET BackupDrive=Z:
    If "%backupdrive%" == "" (
        set Error=No backup drive found.  Please connect a backup drive.
        Goto Error
    REM Your backup line may vary.  Where you specify the backup file name,
    REM make sure you reference the drive letter using %backupdrive%
    ntbackup backup "backupfile" /j "Normal Backup" /f "%backupdrive%\backupfile.bks" /d "Normal - JobName" /v:yes /r:no /l:s /m Normal /snap:off /rs:no /hc:off
    Goto End
    LVL 12

    Accepted Solution

    Plug in the drive that is being mounted at G: and then remount it as F:
    (right-click My Computer, Manage..., Disk Management, right-click F: and then Change Drive Letter and Paths...)
    I think that, as long as you never plug in both at once, they will then both mount as F: by default.

    Each disk has a randomly-generated signature.  Windows remembers what drive letter was last used for each signature and will try to assign the same next time it finds the same disk signature.  


    Author Comment

    I plugged them in at a time.

    I will try and change it like you describe...let you know

    Where is the signature stored....I completly formated the drive...and it still went to G.
    LVL 12

    Expert Comment

    Format is an operation that wipes the contents of a partition.  Signatures are part of the master boot record (which also contains the parition table).

    Author Comment

    i did delete the partition ...but I suspect it is in the boot record.

    In the old days we used to "low level" the drives..but dont know if that is done anymore...

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