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Thread: Cannot see external usb hard drive Ubuntu 20.04 X64

  1. #11
    Join Date
    Jan 2021
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    Ubuntu 20.04 Focal Fossa

    Re: Cannot see external usb hard drive Ubuntu 20.04 X64

    Wow, that's really useful to know. It won't be the issue in this case (as this is a FAT32 drive) but it's a potentially serious problem I'd never heard of. I'm surprised Windows doesn't just unmount external drives prior to hibernation: I wonder if it warns users that they need to plug all such drives back in before powering back on...otherwise (if the external drive is simply unplugged and packed away when the computer comes out of hibernation) presumably the data corruption (that the locking of the external drive aims to avoid) could still happen. Seems like a good reason to stick to vfat on USB drives.

  2. #12
    Join Date
    Jul 2005
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    I think I'm here! Maybe?
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    Hidden!
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    Xubuntu 20.04 Focal Fossa

    Re: Cannot see external usb hard drive Ubuntu 20.04 X64

    You can check the end lines of dmesg by piping the output to tail with command
    Code:
    dmesg | tail
    which by default shows the final 10 lines, I think.

    That is big help in situations like yours, saves a long search of huge text files.
    Last edited by ajgreeny; January 24th, 2021 at 11:54 AM.

  3. #13
    Join Date
    Jan 2021
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    23
    Distro
    Ubuntu 20.04 Focal Fossa

    Re: Cannot see external usb hard drive Ubuntu 20.04 X64

    Yep, 10 lines by default...or if you want to see a few more, you can e.g.
    Code:
    dmesg | tail -n 20
    to view the last 20 (same as for "head", which defaults to the first 10 lines but can dump as many or as few lines as you want with the -n switch).

    Are you sure the drive is physically OK...do you have another machine with which you can confirm that it's still a working drive?
    Last edited by simon-webb; January 25th, 2021 at 01:15 AM.

  4. #14
    Join Date
    Mar 2010
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    22,486
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    Ubuntu

    Re: Cannot see external usb hard drive Ubuntu 20.04 X64

    dmesg -w maybe easier. It is basically dmesg|tail -f

    Also, sudo is not needed with dmesg ... er ... yet. There have been some discussions about properly locking log files, so sometime in the next few releases, sudo may become necessary.

    As for the OP using fat32 or some other file system like exfat, it is possible to make a little mistake. On some linux distros, exfat support is not standard. Extra packages need to be installed.

  5. #15
    Join Date
    Dec 2010
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    22

    Re: Cannot see external usb hard drive Ubuntu 20.04 X64

    OK Sorry it's been so long but I found the problem. It was a bad USB Port. I plugged another portable hard drive into the same port and it was found fine. Then I plugged the one I was having the problem with into another port and it is found fine.

    Thank you all for all your help It was my fault as I should have checked that before.
    Fred Watson

  6. #16
    Join Date
    Mar 2010
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    Squidbilly-Land
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    22,486
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    Ubuntu

    Re: Cannot see external usb hard drive Ubuntu 20.04 X64

    vafred69 - not uncommon. We've all done it. There's something about having to explain stuff to someone else that gets our troubleshooting hats working.
    In general, best to try and isolate what you think is the issue as much as possible.

    Hardware, software, cables. Think logically. Simplify and test. Do that over and over. until the only thing left is too small to split apart for testing, then replace that part/software/cable.

  7. #17
    Join Date
    Dec 2010
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    22

    Re: Cannot see external usb hard drive Ubuntu 20.04 X64

    TheFu, Thanks I guess it was just a panic moment but thanks for the help from everyone here anyway.

    Fred Watson

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