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Thread: install grub only on external HDD

  1. #1
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    install grub only on external HDD

    Yesterday I seem to have installed Xubuntu 12.04.3 onto an external HDD (970 gig) and did so with an Acer 1410 (4 gig, 64 bit). I had to use boot-repair-disc afterwards to restore the Acer's ability to boot. The external HDD appears to contain the appropriate files but won't boot on a Windows 7 (HP dv7 6 gig) machine wherein the bios is set to boot from a USB HDD as first choice. That option seems functional because Knoppix 7.2.0 thumb drive boots satisfactorily. At this time, I don't want my w7 computer to be a dual boot. Instead, I'd like to have Xubuntu booted only when the external HDD is connected and start or restart is initiated. Is there a way to install grub only on the external HDD? GUI preferred if possible.

    Related, long thread has points of relevance but much that differs from my situation.

    In that thread, oldfred wrote:

    I would make sure to have an efi partition on external drive, so you can boot from it. But you can install grub2's efi files to either drive(or both, but then will have duplicate entires in UEFI menu). The advantage of having the efi on the external is that then you can boot from that without the internal drive.

    I install grub2 everywhere. But sometimes it takes some effort to configure it correctly. And now the new UEFI systems have made it a bit more complex as you have to know if booting in UEFI or BIOS mode. But since installer boots in either mode there are ways to configure both.

  2. #2
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    Re: install grub only on external HDD

    Quote Originally Posted by aspergerian View Post
    ... I don't want my w7 computer to be a dual boot. Instead, I'd like to have Xubuntu booted only when the external HDD is connected and start or restart is initiated. Is there a way to install grub only on the external HDD? GUI preferred if possible ...
    The short answer is yes.

    The long answer gets a bit more complicated. Do you want this external drive to be portable (and boot most computers), or only boot this one? Do you want it to boot only in UEFI mode, only BIOS mode or both? Do you want the internal drive to be completely free from any traces concerning booting from the external drive?

    -o-

    I'm guessing now: You want to boot only this computer, and in UEFI mode, and want no traces in the internal drive.

    Then I suggest that you disconnect the internal drive, connect the external one and boot from another external drive (a live system of Ubuntu 64-bits). Install according to the instructions* to the external drive, and check that the installed systems boots (in UEFI mode). If you have problems, use Boot-Repair until it works.

    Then connect the internal drive again, and you should be able to decide which drive to boot with a hotkey to get a boot menu.

    *) There are several sets of instructions, by oldfred here at the Ubuntu Forums as well as Ubuntu wiki pages, for example

    https://help.ubuntu.com/community/UEFI
    https://help.ubuntu.com/community/UEFIBooting
    https://help.ubuntu.com/community/Boot-Repair
    Last edited by sudodus; February 11th, 2014 at 06:11 PM.

  3. #3
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    Re: install grub only on external HDD

    If a Windows 7 system, it probably is not UEFI. Only a few newer Windows 7 systems were installed in UEFI mode.
    But many newer Intel based systems had UEFI, but in BIOS boot mode for Windows 7. So from UEFI/BIOS you may get both UEFI and BIOS boot choices for Ubuntu as 64bit installer is configured for either.

    Boot-Repair should also let you reinstall grub to external.
    Post the link to the Create BootInfo report. Is part of Boot-Repair:
    https://help.ubuntu.com/community/Boot-Info

    But do you want BIOS or UEFI and how is drive partitioned? BootInfo report may help explain how it is currently isntalled.
    For info on UEFI boot install & repair - Updated Mar 2015:
    http://ubuntuforums.org/showthread.php?t=2147295
    Please use Thread Tools above first post to close thread when/if answered completely.







  4. #4
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    Re: install grub only on external HDD

    Sudodus & oldfred, thank you for instructive replies. My responses follow each quote.

    Quote Originally Posted by sudodus View Post
    The short answer is yes.

    The long answer gets a bit more complicated. Do you want this external drive to be portable (and boot most computers), or only boot this one? Do you want it to boot only in UEFI mode, only BIOS mode or both? Do you want the internal drive to be completely free from any traces concerning booting from the external drive?
    -o-
    I'm guessing now: You want to boot only this computer, and in UEFI mode, and want no traces in the internal drive.

    Then I suggest that you disconnect the internal drive, connect the external one and boot from another external drive (a live system of Ubuntu 64-bits). Install according to the instructions* to the external drive, and check that the installed systems boots (in UEFI mode). If you have problems, use Boot-Repair until it works. Then connect the internal drive again, and you should be able to decide which drive to boot with a hotkey to get a boot menu.

    *) There are several sets of instructions, by oldfred here at the Ubuntu Forums as well as Ubuntu wiki pages, for example

    https://help.ubuntu.com/community/UEFI
    https://help.ubuntu.com/community/UEFIBooting
    https://help.ubuntu.com/community/Boot-Repair

    Disconnecting the internal drive is difficult for me because I have Parkinson's which affects my fine motor-control & coordination.


    Quote Originally Posted by oldfred View Post
    If a Windows 7 system, it probably is not UEFI. Only a few newer Windows 7 systems were installed in UEFI mode.
    But many newer Intel based systems had UEFI, but in BIOS boot mode for Windows 7. So from UEFI/BIOS you may get both UEFI and BIOS boot choices for Ubuntu as 64bit installer is configured for either.

    Boot-Repair should also let you reinstall grub to external.
    Post the link to the Create BootInfo report. Is part of Boot-Repair:
    https://help.ubuntu.com/community/Boot-Info

    But do you want BIOS or UEFI and how is drive partitioned? BootInfo report may help explain how it is currently isntalled.
    My HP dv7 arrived new with Vista. I installed Windows 7. I don't think that my dv7 has EUFI. I also have a HP G71 with w7 (6 gig ram) & would like occasionally to run Xubuntu on the G71 by using the external HDD used for the dv7 (if possible & not too difficult).

    My partitioning of the HDD is messy, especially since I went back to gparted and installed / boot -- in hopes that would suffice (It didn't). I made a large FAT32 partition, hoping to transfer copy files from the dv7 HDD to the external HDD, to have those files available to Xubuntu and to w7.

    The choice to use EUFI partitioning on the external HDD is intimidating because I've read so much about EUFI-related problems -- although a Wiki conveys certain advantages to EUFI (here).

    I wouldn't mind a dual-boot via the external HDD (when its connected to dv7 at boot time) but would prefer not to modify the dv7 boot process (if possible).

    I ran Boot-repair this morning and generated an report.


    Appreciation!

  5. #5
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    Re: install grub only on external HDD

    Have you got data (that you have not backed up elsewhere) on the external drive, which you want to use to boot Xubuntu?

    In that case I suggest that, if possible, you backup at least the most important files (photos, documents ... ) before you continue editing partitions and installing systems.

    When your important data are safe, you can start editing the partitions, either start from the beginning or delete and make new partitions for Xubuntu. And you do that when booted from another drive, typically the Xubuntu CD/DVD/USB install drive. Use gparted.

    One easy and safe option should be to use the One Button Installer 'at the advanced level' to install Xubuntu to a fairly big root partition and a small swap partition. That way it should be easy to 'only' touch the external drive and avoid messing with the internal drive.

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    Re: install grub only on external HDD

    Any PC system that was Vista would not have UEFI. UEFI requires gpt partitioning, but you can use gpt partitioning with either BIOS or UEFI if only Ubuntu, not Windows, but it is a bit more advanced. gpt is not required in your case. Gpt is also required for drives over 2TB.

    I do not suggest FAT32 unless you have to have it for some external device like an Xbox. Better to use NTFS as then you can have files over 4GB and NTFS has a journal so repairs may work in cases where they may not work with FAT32.

    Your fstab shows two swaps, one originally from sda. Was that on your other system as not otherwise shown anywhere in this report. I would comment the line after the swap originally on sda5 as that UUID is not anywhere.
    For info on UEFI boot install & repair - Updated Mar 2015:
    http://ubuntuforums.org/showthread.php?t=2147295
    Please use Thread Tools above first post to close thread when/if answered completely.







  7. #7
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    Re: install grub only on external HDD

    Sudodus & oldfred, Thank you again. I've realized that for the last two years or so, I've been writing with Xubuntu 12 while not closely following GPT forum-postings.

    So I reformatted the external HDD as GPT and created an initial partitioning. I'm trying to find a local person to remove my HP dv7's internal HDD, then reinstall it after I have installed Xubuntu 12.04 onto the external HDD.

    A disk-repair report of today's partitioning is here.

    Excerpt:

    => Grub2 (v1.99) is installed in the MBR of /dev/sda and looks at sector 1 of
    the same hard drive for core.img. core.img is at this location and looks
    for (,msdos1)/boot/grub on this drive.
    => No boot loader is installed in the MBR of /dev/sdb.
    My dv7 is not UEFI, and I'm not trying to achieve dual boot via the dv7 but would like the external HDD's Xubuntu to load if that HDD is connected to dv7 at start or restart.

    Before the next install is attempted, ought a boot loader be installed in the aforementioned MBR? Or will GRUB2 be sufficient?

    Much appreciation.

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    Re: install grub only on external HDD

    If you want to select drive to boot with the hotkey and built-in menu, you should have independent drives (which means that each of them should have boot-loaders etc). This way you will also make the operating system on the external drive portable. Just avoid proprietary drivers (unless the same one works for all the computers, where you want to run it).

    What I meant with the One Button Installer is that it can help you install into the external drive without removing the internal one (it will install the bootloader into the drive, where the root file system is installed (for example /dev/sdc <---> /dev/sdc1). But of course, you will be completely sure that the internal drive won't be touched, if you disconnect it.

    Anyway, all installers install the bootloader. If you use the Ubuntu desktop installer, and you have removed the internal drive, I think it will default to the head of the external drive, where you want to install Ubuntu (which is the correct location).

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    Re: install grub only on external HDD

    You now have external sdb drive as gpt and with efi partition shown incorrectly.
    Even if booting currently with BIOS you can use gpt.
    I like to format all gpt drives with a efi partition if in the future you may use drive with a new system that is UEFI.

    But efi partition must be FAT32 formatted and with gparted it is the boot flag that determines that it is efi partition.
    Best if efi partition is first (or near first) on hard drive.
    But to boot in BIOS mode from gpt partitioned drive you also need a tiny 1 or 2MB unformatted partition with the bios_grub flag. Grub will not install correctly without bios_grub partition. Bios_grub can be anywhere on drive.

    You do not have to disconnect drive, but it is often our suggestion for new users to prevent accidental overwrite of first drive, or install of grub for external drive's boot to internal drive. But if you use Something else and use combo box on partitioning screen to see sdb (or whatever external is) to device for grub boot loader install then you should have no issue.

    Install to external drive. Also any second drive.
    And you want this screen to choose where to install the grub2 boot loader which is only available with Something Else or manual install
    https://help.ubuntu.com/community/Gr...ing_Else.22.29:
    Installer version has not changed much so still a good guide except I do not recommend the separate /boot for most systems. Older systems may need it. And some with very large / (root) partitions. BIOS/MBR not for UEFI
    http://www.linuxbsdos.com/2012/07/23...2-hard-drives/
    Attached Images Attached Images
    For info on UEFI boot install & repair - Updated Mar 2015:
    http://ubuntuforums.org/showthread.php?t=2147295
    Please use Thread Tools above first post to close thread when/if answered completely.







  10. #10
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    Re: install grub only on external HDD

    Again, thank you both for the replies.

    I find OBI to seem daunting.

    I tried to create a boot partition, using gparted and selected (guessed) from its tag options. Result is here.

    Getting the EFI boot loader (right phrase?) correct remains unclear to me.

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