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Thread: Problems backing up system with DD

  1. #1
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    Problems backing up system with DD

    I have a PC where Xubuntu 13.10 is installed on USB drive. I would like to make an exact bootable copy of it with DD, but for some reason, a copied USB drive won't boot but it just always opens some "grub rescue" terminal. What's wrong with it?? Everywhere it is said that a drive copied with DD should be an exact copy (like; dd if=/dev/sda of=dev/sdb)

    I also have tried to format the new disk to different file systems with Gparted, and it seems that a disk formatted to ext2 or ext4 and DD'd after that do not work at all i.e. all I get is blinking cursor on a blank screen. Only fat32 is getting me to grub rescue, but nothing works correctly.

    And; the USB sticks are exactly the same type.

    So, could someone please tell me how to do an exact bootable copy of my current USB stick??
    Last edited by AlliumPorrum; February 16th, 2014 at 07:33 PM.

  2. #2
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    Re: Problems backuping system with DD??

    Now I also tried to format the disk on Windows and after that DD from sda to sdb, but no help, it won't boot from a copied disk. What should I try next?

  3. #3
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    Ubuntu 16.04 Xenial Xerus

    Re: Problems backuping system with DD??

    Do you have both still plugged in. Since duplicate and you cannot have duplicate UUIDs, you cannot have both connected at same time.

    dd will not use any pre-formatting as it copies everything, bit for bit.

    Powerful command, but often misused and then nicknamed "dd" Data Destroyer
    http://www.linuxquestions.org/questi...ommand-362506/
    For more info on UEFI boot install & repair - Regularly Updated :
    http://ubuntuforums.org/showthread.php?t=2147295
    Please use Thread Tools above first post to change to [Solved] when/if answered completely.

  4. #4
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    Re: Problems backuping system with DD??

    Quote Originally Posted by oldfred View Post
    Do you have both still plugged in. Since duplicate and you cannot have duplicate UUIDs, you cannot have both connected at same time.http://www.linuxquestions.org/questi...ommand-362506/
    Do you mean that did I have both of them plugged in when I rebooted after the DD? The answer is no, I had just the new copied stick plugged in.

    Is there any good tool for Ubuntu, which would make an exact bit-to-bit copy of a bootable USB stick?

  5. #5
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    Re: Problems backing up system with DD

    1. Please post the command you used to clone the pendrives (the whole command line)!

    2. Please insert both pendrives, run the command

    Code:
    sudo fdisk -lu
    and post the output of the command.

    There might be a number of things that made it fail. For example, that you cloned the partitions, when you should have cloned the whole drive, or if the target drive is smaller (maybe only a little bit smaller).

    If the target drive is slightly larger or exactly the same size, you can use Clonezilla to clone or make an image. Clonezilla does not copy unused blocks, so it is more efficient than dd. But the main advantage with Clonezilla is that it is much safer than 'the disk distroyer'.

    If the target drive is smaller than the source drive, but there is space enough for the files, and it is an 'installed system' you can also use the One Button Installer, make a tarball, and then install the system from the tarball. It will not be an exact copy, but a working system with different UUIDs for the root file partition and the swap partition. The One Button Installer is not intended for live systems or persistent live systems.
    Last edited by sudodus; February 17th, 2014 at 08:56 AM.

  6. #6
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    Re: Problems backing up system with DD

    Quote Originally Posted by sudodus View Post
    1.
    If the target drive is slightly larger or exactly the same size, you can use Clonezilla to clone or make an image. Clonezilla does not copy unused blocks, so it is more efficient than dd. But the main advantage with Clonezilla is that it is much safer than 'the disk distroyer'.
    Thanks sudodus, I will try that! I'll come back if I have any problems with that also ;=)

  7. #7
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    Re: Problems backing up system with DD

    No luck with Clonezilla either :=( The two USB sticks are EXACTLY the same model and size, but still Clonezilla claims that the destination is smaller that the source and it won't do the copying. It says that destination disk is 7.7GB and source is 8.0GB. WTF??

    How in earth can this be so difficult!?!? Isn't there really any simple way to clone the bootable USB stick?

  8. #8
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    Re: Problems backing up system with DD

    Have you checked with
    Code:
    fdisk -lu
    that the target drive has at least as many sectors (or blocks) as the source drive? Clonezilla won't work if the target is one single sector smaller.

    In that case the One Button Installer might solve your problem: Make a tarball, and create a system that does the same thing, but is not exactly the same on the other drive.

    Typical cases for the One Button Installer

    Tool that is easy to use and just works

    The normal linux installers that come with iso files are complicated to use or freeze during the installation process, and you want a tool that is easier to use and just works.

    Replace Windows XP

    Replace Windows XP because you want the computer to work faster or smoother with an Ubuntu based linux operating system, or at the end of life in April 2014, when there will be no more security updates for Windows XP.

    Backup

    You want a simple method to backup (and restore) your whole installed linux system. The One Button Installer combines installation, backup and restore in one set of tools.

    Your own portable Ubuntu based linux system

    You want to make your own linux system portable and port it to a USB pendrive or to be installed in another computer to be used by yourself, or to be uploaded to the internet for sharing with other people. The One Button Installer can do it in a simpler way than to remaster the code and make an own iso file.

  9. #9
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    Re: Problems backing up system with DD

    Well it seems that they are not:

    ~$ sudo fdisk -lu

    Disk /dev/sda: 8011 MB, 8011120640 bytes
    247 heads, 62 sectors/track, 1021 cylinders, total 15646720 sectors
    Units = sectors of 1 * 512 = 512 bytes
    Sector size (logical/physical): 512 bytes / 512 bytes
    I/O size (minimum/optimal): 512 bytes / 512 bytes
    Disk identifier: 0x00027dc0

    Device Boot Start End Blocks Id System
    /dev/sda1 * 2048 13672447 6835200 83 Linux
    /dev/sda2 13674494 15429631 877569 5 Extended
    /dev/sda5 13674496 15429631 877568 82 Linux swap / Solaris

    Disk /dev/sdb: 7798 MB, 7798947840 bytes
    22 heads, 33 sectors/track, 20981 cylinders, total 15232320 sectors
    Units = sectors of 1 * 512 = 512 bytes
    Sector size (logical/physical): 512 bytes / 512 bytes
    I/O size (minimum/optimal): 512 bytes / 512 bytes
    Disk identifier: 0x0002821e

    Device Boot Start End Blocks Id System
    /dev/sdb1 2048 15230975 7614464 83 Linux


    How come is this possible?? I have 5 of these USB sticks that I bought at once (DataTraveler 100 G3 8GB), and they *all* give very different results with fdisk.

    Is there some trick that should be known when formatting the destination? Actually, I would have thought that when making a bit-to-bit copy, it should not matter at all if it even formatted or not..?

  10. #10
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    Re: Problems backing up system with DD

    Quote Originally Posted by AlliumPorrum View Post
    <snipped for brevity>
    How come is this possible?? I have 5 of these USB sticks that I bought at once (DataTraveler 100 G3 8GB), and they *all* give very different results with fdisk.

    Is there some trick that should be known when formatting the destination? Actually, I would have thought that when making a bit-to-bit copy, it should not matter at all if it even formatted or not..?
    It appears to be normal from my recent experience with Lexar Jumpdrives (2 "identical" units weren't exactly "identical" unfortunately) being similar to your situation. I was lucky the larger one was left to take the clone of the first usb stick, but I was shocked at the difference, like you.

    Cloning to a larger drive is OK as has been noted, you may need to adjust partition sizes/filesystems to fill unused space if you like to. As sudodus notes, "one sector smaller", and problems occur though. Always check the destination first with fdisk for sufficient space.

    To clone a usb stick the method I use,
    1. check sizes, with fdisk OR gparted, on BOTH sticks.
    2. shred (zero out) the destination stick (not entirely necessary, dd does a fine job of flattening a destination drive ).
    3. dd the original to the destination stick (formatting the destination is not necessary, dd copies over everything including the drives "unique" identifier etc).
    4. remove the original (and boot, if bootable, the second usb stick) -important to remove the original as oldfred noted, there will be duplicate UUIDs on the system (which can get very messy).

    If you can get a handle on the use of clonezilla, it is a safer option generally than such a low level tool like dd.
    dd has cost me a 75 GB partition full of stored data when an image was restored back to the wrong partition (not enough coffee content in my system that day ), thank goodness for backups that I only lost a few unimportant files after fixing the mess from the backups.
    Last edited by coldcritter64; February 19th, 2014 at 02:24 AM.

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