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External USB Hard Drive Detected, But Not Shown in Computer

    Question

  • Win 7 RC 64 bit freshly installed. I have files on a usb external drive that I want to transfer over to the computer. When I plugged the external drive into the usb port, I got a message that the drivers were installed and everything was working properly. But when I went to "Computer", the drive wasn't shown. I checked "Devices and Printers" and it was shown there as working properly. 

    The files were from a Vista machine, if that makes a difference.

    As a work around, I have connected the External Drive to a Vista Laptop and am wirelessly transferring the files (about 50 GB) very slowly - it's been running about 6 hours at this time with much more to transfer. In order to transfer the files, I had to mark them as shared on the Vista.   
    Friday, August 14, 2009 7:22 PM

Answers

  • Still working on this problem ...Using the "Administrative Tools",  I went into "Computer Management", and then to "Disk management". The USB external drive was there and was said to be "offline". When I moused over the word "offline", i got the following message "This disk is offline because it has a signature collision with another disk."

    What the heck does this mean? I'll be "binging" the message, but maybe someone here can give me a clue. A "signature collision"?
    • Marked as answer by RCoover Saturday, August 15, 2009 9:02 PM
    Saturday, August 15, 2009 8:19 PM

All replies

  • All of your other devices were working correctly right?  No Unknown device in Device Manager?  I am just wondering if the USB root hub or some other piece is keeping it from installing correctly.

    Also, did you reboot after the install?  Never know, shouldnt affect it, but you never know.
    Anything worth doing is worth doing right. Don't forget to vote!!!
    Friday, August 14, 2009 9:53 PM
  • Yes, I did reboot after the External Drive, a 320 GB Seagate Free Agent Pro failed to show up in Explorer. The problem persisted.

    As far as "other" devices being in the device manager, the answer is no! I plugged the device into the machine and unplugged it while watching the device manager. The External Drive was listed as a USB Mass Storage Device - which it is. And did show up under "Devices and Printers" and, according to it's properties, was working properly. 

    I also have a USB SATA drive dock which I tried, and it worked on the Win 7 machine, showing in explorer. The problem, of course, was that my backup files that I needed were on the External Seagate ...

    This all started when the hard drive on my desktop failed. I purchased another drive to replace it and decided to try Win 7 RC 64 bit on the new drive. I backup regularly, so I did not think I'd have a problem. Thankfully, I was able to work around the problem by using my laptop to send the files to the desktop ... still I should be able to use the External Drive with the desktop and I cannot.
    • Proposed as answer by Geez51 Saturday, August 15, 2009 4:52 AM
    Saturday, August 15, 2009 12:26 AM
  • How many drive letters are being used? (C,D,E?) It might be that you have used up all of your local drive letters. Normally the local drive letters are C,D,and E. If your pc is recognizing the USB device, but is not giving you a drive letter, you might check this. I have seen it to where you have to go in to disk management in My Computer and assign a drive letter to the device. Not sure if this is your issue, but you might want to chek it out anyway.
    Good luck!
    • Proposed as answer by Geez51 Saturday, August 15, 2009 4:59 AM
    Saturday, August 15, 2009 4:58 AM
  • No, that isn't the issue. As I mentioned above, a drive letter is given to a USB SATA dock. And not three minutes ago, I inserted a USB Flash Drive and it was assigned a drive letter.

    No, the problem here is that their must be some hardware incompatibility with the Seagate External Drive (FreeAgent Pro).

    The external drive, by the way, also has, in addition to the USB connector, an external SATA connection, but I don't have the cable and I don't have a connection to the computer for an external SATA cable. If I lived close to a decent computer parts house, I'd probably go out tomorrow and purchase the cable and PCI connector. Unfortunately, I live 50 miles away from everything (except a Radio Sh ... , about 10 miles away) Any body have any idea if trying the SATA connection might work or would I run into the same problem?
    Saturday, August 15, 2009 7:02 AM
  • Still working on this problem ...Using the "Administrative Tools",  I went into "Computer Management", and then to "Disk management". The USB external drive was there and was said to be "offline". When I moused over the word "offline", i got the following message "This disk is offline because it has a signature collision with another disk."

    What the heck does this mean? I'll be "binging" the message, but maybe someone here can give me a clue. A "signature collision"?
    • Marked as answer by RCoover Saturday, August 15, 2009 9:02 PM
    Saturday, August 15, 2009 8:19 PM
  • Back into "Adminstrative Tools", right click on "offline" and get the option to place the disk "online". A left click then solved the  problem.

    Still don't know what a "signature collision" is (other than an automobile body repair shop - that is what I found on Bing).

    But all is well with the world, at least the Windows 7 part.
    Saturday, August 15, 2009 9:09 PM
  • right clicking on offline and bringing the drive to online status worked for me, this was win7 64bit with 2 western digital mybook 1tb hard drives
    • Proposed as answer by Rich Gillin Sunday, April 01, 2012 8:50 PM
    Friday, September 11, 2009 6:27 PM
  • Two answers for you.  The first is for somebody who had the same issue you did and wrote about it..
    http://blogs.chron.com/techblog/archives/2009/09/signatures_in_collision_bringing_back_a_120gb.html

    The second is from a MSDN article (Microsoft Developer Network)
    http://msdn.microsoft.com/en-us/library/dd405638(VS.85).aspx

    In the second article near the bottom and above the Requirements section you will see this:

    When a volume is offline, the VDS_VF_PERMANENTLY_DISMOUNTED flag is set in the ulFlags member of the VDS_VOLUME_PROP2 structure, and the VDS_VS_OFFLINE volume status value is also set in the status member of this structure.

    For GPT and dynamic volumes, the unique identifier that the pUniqueId member points to is globally unique.

    For removable media drives, the volume exists and has its own unique identifier even if there is no media in the device. If a volume is formatted on removable media, that volume has its own unique identifier. For more information, see Supporting Mount Manager Requests in a Storage Class Driver.

    The format of the unique identifier may vary among different types of devices and volumes. For basic volumes on MBR disks, the unique identifier is based on the disk signature and partition offset. Because the disk signature and partition offset are DWORD values, the unique identifier cannot be guaranteed to be globally unique across computers.

    If the disk signature changes, the volume’s unique identifier also changes. Disk signature changes usually occur as a result of a collision during disk cloning.

    Note that a unique identifier is not the same as a volume GUID path. To find the volume GUID paths for a volume, use the IVdsVolumeMF3::QueryVolumeGuidPathnames method


    ---------------------------------------------

    So, looks like something happened and the OS is now seeing this disk signature as being used already.  By choosing to bring it online it looks like you told it to ignore the error.  Anyway, thats probably the technical "why" it happened.


    Anything worth doing is worth doing right. Don't forget to vote!!!
    Friday, September 11, 2009 6:45 PM
  • I just had the same problem. The fix is stupidly simple. When you mouse over the  word "offline", just right click on it and select "online". That will give the drive a new drive letter and the system will be happy. You can't just give the drive a new letter on your own, because Win7 writes a "signature" for each drive and if the drives are too similar, it gets confused.

    There's more about this at: http://blogs.chron.com/techblog/archives/2009/09/signatures_in_collision_bringing_back_a_120gb.html
    • Proposed as answer by pjay83 Thursday, January 07, 2010 2:32 PM
    Friday, November 06, 2009 5:35 PM
  • Thank you sooo much Data Doc!!!

    I messed around with that stuff for 2 hours until I found your "easy guide to success"! ;-)

    peter
    Thursday, January 07, 2010 2:33 PM
  • Thanks so much. I spent a lot of time reading many articles.


    VSDOTNET2008
    Tuesday, March 23, 2010 9:49 PM
  • Worked! To think I spent hours trying to fix it. Thank you!

    Monday, April 19, 2010 5:39 PM
  • Thank you so much! This fixed the problem I was having with my old laptop hard drive!
    Saturday, July 24, 2010 6:21 PM
  • phish4rob,
    Thank you! That fixed this problem for me.

    Wednesday, September 29, 2010 5:07 PM
  • And, just in case that doesn't work...

    I have a WIN7 64-bit system with a 1TB & 2TB WD external drives.  I wanted to add a second 2TB WD device.  Got the error message.  Mousing over the message or any other option in Disk Manager wouldn't work.  Apparently WD clones all their drives and they all have the same ID number.  Sigh ... so:

     

    Used DiskPart, a CMD utility as follows:

    List Disk   <-- note the space

        ^-- this lists all the drives units.  Find the spec that matches the "missing" drive

    Select Disk #

        ^-- where # = the drive number of the missing drive

    Uniqueid Disk

        ^-- this shows you the drive ID.  Ex. 0005A4E2

    Uniqueid Disk id=xxxxxxxx

        ^-- change xxxxxxxx to any other 8-digit HEX number

              ex. 0005A4E3

     

    Exit the CMD box & reboot.  Your "missing drive" will automatically be assigned the next available drive letter and you are in business.

    Tuesday, October 05, 2010 10:42 PM
  • Thanks so much.

    Right click on Offline and change it to Online also work for me.

    But I'm also need to know what cause is it and I'll try to find'em.

    Wednesday, November 24, 2010 2:36 AM
  • This also worked for me. I did see the problem with the my disk, I believe it was the restore partition as I was trying to read a HP C/ drive mounted in a USB enclosure on another HP?? Anyway I was able to recover my last years tax files.....
    Tuesday, January 25, 2011 11:11 AM
  • Had the same problem with a similar pair of Seagate drives. This process worked like a charm. Thanks!
    Thursday, January 27, 2011 1:27 PM
  • this is all well and good and i think i am pretty close but when i try to put the drive online or initialise the disk it is coming up saying the drive is 'write protected' is there any way that i can change this without having access to the drive??

    Drive: WD elements 1023 

    computer is running win7

     

    any help would be greatly appreciated??

    Thursday, June 16, 2011 5:44 PM
  • I also thank you for the solution! In my case, the two drives were from a RAID mirror.

    Where would we be without the Internet and all the exceedingly helpful people out there? :D

     


    • Edited by sburchett Monday, July 04, 2011 5:47 AM typo
    Monday, July 04, 2011 5:47 AM
  • I just had the same problem. The fix is stupidly simple. When you mouse over the  word "offline", just right click on it and select "online". That will give the drive a new drive letter and the system will be happy. You can't just give the drive a new letter on your own, because Win7 writes a "signature" for each drive and if the drives are too similar, it gets confused.

    There's more about this at: http://blogs.chron.com/techblog/archives/2009/09/signatures_in_collision_bringing_back_a_120gb.html

    The most stupid thing that i had ever seen !!!

    this solution is ok ;-)

    Saturday, July 23, 2011 9:52 AM
  • The most stupid thing that i had ever seen !!!

    this solution is ok ;-)

    Therefore its a stupid OS. Same problem here, but when i reboot into Linux there was no problem...
    Sunday, April 15, 2012 6:32 PM