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  1. #1
    2 Star Lounger
    Join Date
    Mar 2002
    Waltham, MA, USA
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    How to make exernal USB drive letters stick?

    When I add an external SATA drive, I have to restart the computer to get Windows to recognize it, but also, the drive letters of external drives with USB connections change. The eSATA drive will take the lowest drive letter that is unoccupied by another SATA drive. I have to go into Control Panel > Administrative tools > Computer Management > Storage to change the drive letters back so software (and I) will find files where expected. Sometimes I have to use a temporary drive letter as an intermediate step, because the drive letter I want to change to is already occupied. Is there a way I can:

    * Make Windows 7 hold onto the same drive letters for USB drives when a new eSATA drive is added;

    * Recognize the eSATA drive without my having to restart the computer?

    Might one useful trick be to place the USB drives in the middle of the alphabet so the eSATA drive can use a lower drive letter without affecting the other drives? Better would be if the USB drives just stay where they are, no matter what.

    This could also be an issue that requires a BIOS solution, as the computer does recognize drives before Windows starts. Seems to me that Winodws ought to be able to undo the confusion, though, automating the process I have to do manually.

    The computer is a PowerSpec G160 tower, specs are at and it is running Windows 7, Service Pack 1.

  2. #2
    4 Star Lounger
    Join Date
    May 2012
    Thanked 49 Times in 39 Posts
    AHCI needs to be enabled in the BIOS for the eSATA drive to get "hot plug" support.

    See also:

    USB drive letters are usually port related i.e. a specific port will enable a specific drive letter.

  3. #3
    Super Moderator bbearren's Avatar
    Join Date
    Dec 2009
    Polk County, Florida
    Thanked 450 Times in 356 Posts
    The workaround I use is to go to the management console and assign my eSATA drive a drive letter way down the alphabet. I still have to reboot (hot-plugging in Windows 7 is not all it's cracked up to be) but Windows remembers the drive letter assignment for my eSATA drive, and my USB drive letters stay unchanged.
    Last edited by bbearren; 2012-06-27 at 21:21.
    Create a fresh drive image before making system changes, in case you need to start over!

    "The problem is not the problem. The problem is your attitude about the problem. Savvy?"—Captain Jack Sparrow "When you're troubleshooting, start with the simple and proceed to the complex."—M.O. Johns "Experience is what you get when you're looking for something else."—Sir Thomas Robert Deware.
    Unleash Windows

  4. #4
    5 Star Lounger
    Join Date
    Dec 2009
    S.F. Bay Area, California, USA
    Thanked 85 Times in 83 Posts
    You might try this program out, too (note there are both 32-bit & 64-bit installs).


  5. #5
    Join Date
    Jul 2010
    Thanked 0 Times in 0 Posts
    Probably not worth a whole lot, but I'll throw it out anyway, just in case...
    I used to have a very similar problem with optical drive letters changing in XP - that was caused by ZoneAlarm. Haven't used that product since then.

    As for your specific problem with W7 - I do not think I have seen it. I use numerous external eSATA and USB drives with three different W7 computers (Home premium and Pro), all have very specific drive letters set for recognition purposes (generally between T and Z), and none of them change unless I happen to accidentally connect one to a computer where the pre-set drive letter is already in use. For example, I can have multiple external drives all set to X:, and each drive always shows up as X: UNLESS I happen to connect two of them to the same computer at the same time.

    I do not use any special tools or utilities for this function - it has just worked fine for me ever since I started using W7. good luck getting it sorted out.

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