Windows10 not recognizing 2 Toshiba ext HD at same time Solved

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  1.    02 Mar 2018 #1

    Windows10 not recognizing 2 Toshiba ext HD at same time

    This is an intricate thing to try to describe so here goes. I have 2 Toshiba external hard drives no model number (I assume they are identical). Plugged in one to USB and it was immediately recognized and assigned H drive. Plugged the other into another USB and this one is not recognized at all in the window This PC/Devices and Drives. Same thing if I try all other 5 USB inputs on CPU. The first one stays recognized throughout and all content is accessible. If I unplug the first one and then plug in the second one, the second one is immediately recognized and assigned the H and all content is accessible. Try adding the first one back in, both plugged in at same time, same problem no dice. I leave them both plugged in and I go to control panel/devices and printers. It shows icons for the two external usb 3.0 devices connected. If I right/click on the icons and choose browse files for each it shows exactly the same content (content from whichever device was first device connected). So it appears while it is at some level sensing two devices, when I try to access from the devices and printers window it's treating the two icons as the same device. I also have a Seagate external hard drive. If I plug the Seagate to USB and one of the Toshiba to another USB, they are both recognized and assigned G and H and all content is accessible. So Windows thinking two drives are the same one, is this fixable? I tried renaming one drive (right click/rename in This PC) but it didn't fix it. Also would anyone know were I to buy an external hub and have all three of the external HD thus coming in through one USB slot, if this would fix or get around the problem. thanks for any help
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  2. Bree's Avatar
    Posts : 9,185
    10 Home x64 (1809) (10 Pro on 2nd pc)
       02 Mar 2018 #2

    Welcome to TenForums @beovertherenow

    As it happens, I have two identical Toshiba external HDDs I can test this with.

    I have successfully recreated your problem by turning off automount. Automount automatically assigns drive letter to volumes that are added to the system, so your two identical drives would each get different letters when plugged in.

    When automount is off the drive letter used is whatever you first gave it. Both your Toshibas were originally assigned H: and (obviously) you can't have two H: drives at the same time. So when both are plugged in only the first to be plugged in can be seen. Your Seagate has a different letter (G) so that explains why you can see two drive if one is the Seagate.

    To turn on automount, open a command prompt (admin) and type DISKPART

    At the DISKPART> prompt, type AUTOMOUNT ENABLE

    You can now close the command prompt and try your two HDDs. The first will get H: as usual, the second will get another drive letter.
      My ComputersSystem Spec

  3.    03 Mar 2018 #3

    Hi I tried your suggestion a couple of times making sure I was using admin command prompt but it didn't work. it's still not assigning the new letter name when the second Toshiba drive is added to USB input. also tried uninstalling both devices from the device manager and then restarting and then hooking them up again, but it was the same deal, added the H drive, then either nothing or replaced the H drive. I was really hoping it might be as easy as you stated, if you have any other ideas thanks for your help
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  4. Bree's Avatar
    Posts : 9,185
    10 Home x64 (1809) (10 Pro on 2nd pc)
       03 Mar 2018 #4

    Well, it was easy to create the same type of problem for myself, and to undo it after testing.

    Plug in both the Toshiba drives. Open Disk Management and post a screenshot, that may help diagnose the problem.

    Disk Management - How to Post a Screenshot of

    It's late here, I'll have a look at it in the morning (in my time zone, that is).

    Another suggestion - can you try both drives at the same time in another PC? Do they both show up, or only the first one? That would point to it being something about the drives themselves. I have an idea on that, but it's only worth trying if we can confirm it's the drives causing the problem, not the PC.
      My ComputersSystem Spec

  5.    03 Mar 2018 #5

    I have family in UK so I figured you were either up late or up early. I just happened across a post about disk management so I went there and it showed the disk offline because of signature collision. I force changed the drive letter on the online one to "I" then plugged them both back in. This time they both came up as "I" instead of "H" with one of them still showing up offline when they were both plugged in. I tried it again making sure only one was plugged in changing it back to "H" then plugging in the second one hoping it would stay at "I" but no go. So now they are both showing up as "H" again when deviced and one still offline in disk management. What do you think about emptying one drive and reformatting it or something and try reintroducing it as a "fresh" drive. Here is the screenshot

    Click image for larger version. 

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  6.    03 Mar 2018 #6

    I realized I probably should have included a more complete screenshot of the DM box. Here it is

    Click image for larger version. 

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  7. Bree's Avatar
    Posts : 9,185
    10 Home x64 (1809) (10 Pro on 2nd pc)
       03 Mar 2018 #7

    Your Disk 3 is shown as Offline, with no name or drive letter.

    When I turn off Automount I too see no name/letter in Disk Management, but the 'missing' drive is still Online.

    With all the drives plugged in as they were for the Disk Management screenshot, run diskpart again.

    Type the sequence of commands...


    ...and post the results.

    and yes, I'm up late - this time I'm really going to bed :) - I'll look at the result (very late) morning.
      My ComputersSystem Spec

  8. Bree's Avatar
    Posts : 9,185
    10 Home x64 (1809) (10 Pro on 2nd pc)
       03 Mar 2018 #8

    I suspect both have the same ID, hence the signature clash. If so, the ID can be changed for one of the disks to avoid the clash, no need to reformat and no data need be lost.

    In diskpart, type HELP UNIQUEID DISK for instructions.

    Night night, see you tomorrow...
      My ComputersSystem Spec

  9.    03 Mar 2018 #9

    thanks for all your help I solved it another (and luckily easier) way by searching for forums on signature collision. So long as you're sure you're not messing with the OS drive you can hover the cursor over the Disc 3 box where it has the little red warning thing until you can get a right click selection that includes ONLINE. Clicked ONLINE the computer churned around a little bit and then assigned the offline drive a new letter and put it online so now I have access to all three external drives at once. Restarted and reconnected everything to make sure it worked. Again thanks for all your help especially pointing me in the right direction

    (this solution found here look for final post by MathewsRL
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  10. Bree's Avatar
    Posts : 9,185
    10 Home x64 (1809) (10 Pro on 2nd pc)
       03 Mar 2018 #10

    For the definitive explanation of signature clashes see this TechNet article by the legendary Mark Russinovich.

    You'll see at the end of the article he uses 'diskpart uniqueid' to set the signature, so we were working towards the same end after all.

    Glad it's all sorted for you now.
      My ComputersSystem Spec

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