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Thread: Booting from external HD

  1. #31
    Join Date
    Mar 2007
    Beans
    676
    Distro
    Ubuntu Development Release

    Re: Booting from external HD

    Quote Originally Posted by oldfred View Post
    If you can boot into the external, then try the full uninstall and reinstall of grub2 and be sure to install grub2's boot loader to sdb.


    You can skip the chroot if you can boot into your install.
    drs305 chroot to purge & reinstall grub2
    http://ubuntuforums.org/showthread.php?t=1581099

    Sometimes this works, but it does not uninstall grub to make a totally clean reinstall.
    #to get grub to remember where to reinstall on updates:
    sudo dpkg-reconfigure grub-pc
    #Enter thru first pages,spacebar to choose/unchoose drive, enter to accept, do not choose partitions
    #To see what drive grub2 uses see this line - grub-pc/install_devices:
    sudo debconf-show grub-pc
    Well, that was fun!

    I tried the reconfigure, which didn't help. So I tried the chroot route.

    I chrooted into one of the installs on the external HD OK, but running update-grub and grub-install /dev/sdb left me still unable to boot from grub in the external HD. Purging and re-installing grub2, and letting the grub files be written to BOTH sda and sdb left me unable to boot from either drive - both gave "file not found" errors. I had to boot from the LiveCD (actually a USB flash drive!) and chroot from there into one of the installs on the internal drive to re-install a working grub2 on /dev/sda.

    Now I'm back where I started, and more and more convinced it's a disability of the Sony to access USB devices before the kernel is loaded, which means it won't ever boot from the external drive unless I can get PLOP working.
    Sony vaio vgn-fw235j; Synaptics touchpad; triple boot: mint 12 64-bit; Precise 64-bit & Saucy 64-bit. 2TB external USB drive with more...

  2. #32
    Join Date
    Jun 2009
    Location
    SW Forida
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    Hidden!
    Distro
    Ubuntu 16.04 Xenial Xerus

    Re: Booting from external HD

    I think the newest grub 1.99 does require you to use the same version liveCD/USB to run the 'simple' updates.
    Chroot should work from any Linux as then you are working from inside the install.
    I have seen many reports of plop working, but have not used it, nor know how easy it is to configure.
    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.

  3. #33
    Join Date
    Mar 2007
    Beans
    676
    Distro
    Ubuntu Development Release

    Re: Booting from external HD

    Quote Originally Posted by oldfred View Post
    I have seen many reports of plop working, but have not used it, nor know how easy it is to configure.
    Well, that fixed it! I downloaded PLOP, extracted the binary and copied it to the /boot folder of the "grub master" install on the internal HD. Then I created a boot stanza for it and inserted it into grub.cfg - I'll put it in with /etc/grub.d/40_custom later. Choosing the PLOP entry from the Grub2 menu gives me a PLOP menu. Choosing USB from that takes me to the Grub2 menu based on the MBR of the EXTERNAL HD, from which I can choose any of the installs (of course I made sure to run "update-grub", and had already done "grub-install /dev/sdb" from the chroot).

    Booting from the /dev/sda Grub2 menu is not affected UNLESS I choose PLOP from it.

    Thanks for the suggestions, and for sticking with it!
    Sony vaio vgn-fw235j; Synaptics touchpad; triple boot: mint 12 64-bit; Precise 64-bit & Saucy 64-bit. 2TB external USB drive with more...

  4. #34
    Join Date
    Jun 2009
    Location
    SW Forida
    Beans
    Hidden!
    Distro
    Ubuntu 16.04 Xenial Xerus

    Re: Booting from external HD

    Glad that worked.
    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.

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