How to force USB HD to use a Specified letter

By girardfrancois ยท 13 replies
Oct 4, 2005
  1. Hey everyone !!

    I bought 3 WD 200go HD and 3 usb case to do my backups for a server in a company.

    I did format de drives one by one and changed the letters of each drive to Z:

    For some reasons, everytime i disconnect a drive, and reconnect another one, it changes his letter automaticly to I: !!! :confused:

    Also, if i format and force a drive to use Z:, disconnect and reconnect the same drive, i does keep his letter. BUT as soon as i disconnected it and connect another one, i lose the Z: letter and get back to I:and so ON for all of my usb hard disks. :eek:

    Did anyone ever seen this issue
    Thank you verry much
  2. jobeard

    jobeard TS Ambassador Posts: 11,137   +985

    I believe (but can't prove) that the mfg serial number is used to recognize each device
    as "I've already seen this before" status. My Flash drive was competing with my
    removable 120gb and I couldn't get both on at the same time. Solution was
    to mount one, assign the drive letter leaving it mounted, and then mount the
    second to assign it a different drive letter. Once done, I can now mount them independently,
    keep an Icon on the desktop for each, and regardless of which USB slot I use to plug-in, everything works out correctly.
  3. girardfrancois

    girardfrancois TS Rookie Topic Starter


    mmmmm.... i did that and for sure it does work but the idea is that i dont need these drive to be connected at the same time because i only connect one a day to do my backup on a win2000 server.

    Like i said earlier i connected one usb hd and force him to use the Z: letter and it does work, but if i disconnect this drive and connect an identical usb drive, i have to set the letter Z: again. heres the tricky part, if i disconnect the drive that i just gave the Z: letter and reconnecting it, it keeps the Z: letter BUT if i disconnect it once more and reconnect the other usb HD that is exactly the same, i loose the Z: letter and get back the one it has before.

    kind of a weird issue because at one of my other client, i sold them 3 wd 120go that comes already in prefab usb cases and when i force them to use a letter it works just fine. i can disconnect a drive and connect the other one and he gets the Z: letter !!!
  4. jobeard

    jobeard TS Ambassador Posts: 11,137   +985

    that's fine, but you want predictable behavor instead of chaos. use the concurrent
    setup ONLY to get the drive letters assigned. After that it will not matter any more.
    Getting each drive its own drive letter will simplify your life - - even allow scripting to known locations.
    I understand that this isn't what you expect, but making it all work is like to make you happier that continued fussing with Z:\
    {btw: what makes Z the 'only correct drive' and why can't any other assignment be allowed ?}
  5. mikescorpio81

    mikescorpio81 TS Rookie Posts: 293

    Once you plug in HD's like the ones u say u have, dosen't WIN just give it the next available drive letter (default)? Does it really matter what letter they are? As long as u can see them an access them I dont understand why you would need a specified letter. Fair enough if you are mapping a drive to one of them, but you are constantly removing them so its kind of hard to have a specified drive letter all the time. What if a pc u plug your Hd into already has a drive of the same letter?
  6. girardfrancois

    girardfrancois TS Rookie Topic Starter

    Its because im using them with Veritas Backup and when you configure a media to do the backup, you have to specify a drive. So to make sure that my backups work well, i wanted to make sure that all of my usb drive had the same letter instead of letting WIndows giving me the next available letter..... it was a precaution i took to do this like that just in case that i left my usb memory stick in usb port of my server... so if the letter of the drive changed, my backup with veritas would not start because the drive letter would have changed.
  7. jobeard

    jobeard TS Ambassador Posts: 11,137   +985

    Well, it's just a matter of a few clicks to reconfig the backup source drive and
    instead of being phobic on Z:, why not use the I: instead?
  8. girardfrancois

    girardfrancois TS Rookie Topic Starter

    yeah i know its just that since we have many customers, im just trying to put some similarity beetween them... its juste that i dont understand WHY with these drive its not working and with these one WD model wd1200b015 -rnn its working... could it be that the ROM in these drive s different ?
  9. fozzie

    fozzie TS Rookie


    I had this same problem with 2 identical Seagate USB drives with Veritas.

    My solution was to plug the first one in and right click on my computer,manage, disk management and change the drive letter of the external USB drive.

    If they are the same it doesent matter which one you connect they should all receive the same letter you specified. I have both my Seagate drives on Y drive and another Laser drive on Z. Veritas doesent seem to mind either. :)
  10. patio

    patio TS Guru Posts: 482

    Try skipping say 3 or 4 Drive letters from the last drive on the machine and assign this one instead of Z:
    Then create a restore point. This will save that drive assignment to the removable drive.

    patio. :cool:
  11. hchhimself

    hchhimself TS Rookie

    Same problem here!!!

    I encounter exactly the same problem - and I cannot just change the Veritas Backup Exec to use the first available drive letter, as I have 3 different users who logon to this machine. And they all get different network letters assigned - as part of a special office application.

    Any solution to this problem?? It is really annoying and googling for hours have only provided me with a monstrous headache so far...

    kind regards

  12. girardfrancois

    girardfrancois TS Rookie Topic Starter

    dear friend !!!!

    My only solution to my problem that i did find, was to set Veritas on my server, and let my server dedicate a letter.. for example, he gave me the G letter because when you cnnect a usb device, windows give you the next available letter.

    So to make sure that i keep this letter, i make sure in my login script that i do not map the G letter. But if you remove any network drive that are below the G letter for example F, next time you will reconnect the usb drive, it will use the F: letter.

    I wish we could force widows using the same usb letter with some kind of MAC address that comes from a hard drive !!! You know just like on a dhcp server when you force an ip to be used on 1 workstation for ever !!!!

    Anyway hope this could help you a little bit
  13. jobeard

    jobeard TS Ambassador Posts: 11,137   +985

    Sadly, Windows maps the attachment to the next free drive letter, so this will
    change anytime a lower letter is freed-up or some other device attached prior to.

    For myself, I leave the drives attached (and therefore mapped) when I shutdown.
    This saves the drive mappings for the next boot-up. If the mapped drives are not
    available upon booting, they show up as 'disconnected' with the correct drive mapping
    from the last attachment.

    So, if at all possible, attach the drives once and just leave it attached.
  14. donhams

    donhams TS Rookie

    I think I've got the solution that you seek

    This software works on Win2000 & newer. I have 5 ext USB drives (with Veritas) with lots of network letters. Enjoy:

    Hmm techspot will not allow me to post link, so you'll need to google:


    that stands for USB Drive letter Manager
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