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Thread: Howto help USB boot drives

  1. #11
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    Re: Howto help USB boot drives

    Quote Originally Posted by runrickus View Post
    This as you have already pointed out
    The following pendrives do not work because they are not found after the Plop bootloader transfers control to the USB system.
    Sandisk Cruzer Blade USB 2, 4 GB (which has worked 'everywhere' before)
    Sandisk Cruzer Ultra USB 2, 8 GB
    Is the only problems I have encountered..
    What else do need me to test sudodus??
    Kind Regards
    1. If you have a pendrive that is much slower than when it was new, you can wipe the whole device, and after that check if it is fast again. But don't do it on a good pendrive, that would only cause unnecessary wear of the memory cells.

    2. If you have a pendrive with a bad FAT16 or FAT32 file system, you can try to repair it with the linux tool dosfsck. I'm not sure how much it can do compared to the Windows tool chkdsk.

    *. Otherwise I don't know right now, but I'll come back and ask (hoping that you will have time to test when that happens).

  2. #12
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    Re: Howto help USB boot drives

    (hoping that you will have time to test when that happens).
    I will make the time..
    I have bought a couple of SanDisk Cruzer U 16 Gigs, Real Cheap and they are just waiting for you..
    Thanks sudodus

  3. #13
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    Re: Howto help USB boot drives

    Checking the iso file and the boot drive - detailed tips

    There are two ways to check the md5sum.

    1. Check the whole iso file with md5sum versus the listed value

    at https://help.ubuntu.com/community/UbuntuHashes, for example

    Code:
    $ md5sum ubuntu-16.04-desktop-amd64.iso
    c94d54942a2954cf852884d656224186  ubuntu-16.04-desktop-amd64.iso
    or if you have the md5sum in a file with a line, where the file name is following the md5sum (usually separated by two spaces like the output above)

    Code:
    $ md5sum -c ubuntu-16.04-desktop-amd64.iso.md5
    ubuntu-16.04-desktop-amd64.iso: OK
    2. Check the packages in the install drive with the boot menu option 'Check the disk for defects'

    Discussion

    If there is a checksum error, it depends very much where it is. Some program package might be damaged, that you are not using (at least not during the first few days). But if the checksum is bad, there is often a big damage, and you will not be able to create a working boot drive from the iso file.

    1. iso files

    Most bad iso files are caused by bad internet connections. The quality of internet connections is improving over time, and bad downloads are less common nowadays compared to a few years ago. One failure is that the connection failed before the whole file was downloaded. So the file is too small. Using a torrent is reliable because it checks the md5sum automatically. The same holds for zsync which is available at the Ubuntu QA testing tracker.

    2. Check the disk for defects

    2.1. Optical disks

    I think most failures at 'Check the disk for defects' (when the iso file was good) are caused by bad burning, for example a failing optical drive or too high burning speed. It is a good idea to burn at the lowest possible speed. I have good experience of k3b, that can be installed in any flavour of Ubuntu (not only Kubuntu).

    See the following link for more details, BurningIsoHowto

    2.2 USB pendrives

    Flashing the iso file to a USB pendrive is very reliable with cloning tools, but can fail with tools that depend on interpreting the internal structure of the iso file, if the tool is not up to date with the particular linux system in the iso file. If a USB pendrive is bad (physically bad with damaged sectors of memory cells), it will usually be read-only or dead, rather than accept writing but not store the data correctly.

    See the following link for more details, Installation/FromUSBStick
    Last edited by sudodus; September 18th, 2016 at 03:07 PM. Reason: simplified title

  4. #14
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    Re: Howto help USB boot drives

    Restore a USB boot drive

    You may want to re-use the USB pendrive as a standard storage drive (after installing Ubuntu). If the boot drive was cloned from the iso file (with mkusb or the Ubuntu Startup Disk Creator alias usb-creator-gtk version 0.3), there is a read-only iso9660 file system, and you must restore the drive. The standard is an MSDOS partition table (MBR) and a partition with the FAT32 file system.

    1. You can format the USB pendrive completely (including MBR) using gparted in Ubuntu or Disk Management in Windows. This works in most cases.

    2. Otherwise you can use mkusb and mkusb-nox, which have built-in features to wipe the first megabyte, create a new partition table and file system.

    It is easy to use mkusb-nox in a terminal window (but you must install it, which is described in both links below).

    Code:
    sudo mkusb-nox restore


    See the following links (and links from them),

    Postrequisites - restore the USB stick

    https://help.ubuntu.com/community/mkusb
    Last edited by sudodus; September 12th, 2016 at 12:03 PM.

  5. #15
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    Xubuntu Development Release

    Re: Howto help USB boot drives

    Reopened per OP request

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