I'm trying to install Lubuntu to a USB drive, but I'm having a difficult time installing GRUB to the drive. The rest of the install seems to go fine.

This is what I have tried

  1. Went through the normal install process. At the end of the process I got an error

    Executing 'grub-install /dev/sdf' failed. This is a fatal error.

    It then prompted me to try to reinstall GRUB or continue without a bootloader. I attempted to reinstall, but this seemed to have no effect as I was left with a non-bootable drive.

  2. After the normal install failed I tried

    mount /dev/sdf1 /mnt/USB
    grub-install --force --no-floppy --root-directory=/mnt/USB /dev/sdf

    This gave me an error. I can't remember the exact error at the moment, but I can try to run it again later and edit the question.

  3. I then ran Boot-Repair and used the advanced options to select "Reinstall GRUB" on "/dev/sdf". Boot-Repair wouldn't do this on my normal install (I don't know why) and told me I needed to boot into a LiveCD environment.

    I did this and Boot-Repair ran, but gave an error. I don't know why, it simply said, "Boot-Repair ran with errors." Nothing more descriptive than that. Needless to say, I still couldn't boot.

  4. I finally tried the following

    sudo mount -t ext3 /dev/sdf1 /mnt/USB
    sudo mount -t proc none /mnt/USB/proc
    sudo mount -o bind /dev /mnt/USB/dev
    sudo chroot /mnt/USB /bin/bash
    grub-install /dev/sdf

    This gave no errors and seemed to successfully install GRUB to my USB drive. Unfortunately it still doesn't boot.

When I boot from the drive I get a blank screen with a flashing cursor.

How can I install GRUB to this disk and get it to successfully boot? Moreover, why is the GRUB install failing in the first place?

  • are you sure the option --root-directory is correct? Isn't it --boot-directory?
    – Samik
    Jun 18 '12 at 13:30
  • @Samik According to the man page you are correct. I copied the command from here. I can try running that command again later today with the correct parameter name. Jun 18 '12 at 13:37
  • you can also try this procedure
    – Samik
    Jun 18 '12 at 13:55
  • It needs to be an msdos partition scheme.
    – mchid
    Jun 4 '16 at 3:48
  • Can you provide the output of sudo fdisk -l and indicate which device is your USB drive? If you have a UEFI motherboard, you'd probably want a GPT partition table where the first partition is an EFI partition with your /boot files on it, and your second partition is your root filesystem. Otherwise, you'd want an msdos (MBR) table with a FAT32 partition for /boot or for the entire root filesystem. Dec 20 '16 at 20:59

GRUB install can fail on the USB because its MBR is too small.

To install Lubuntu on the USB, I would simply create a persistant live-USB, via UnetBootin or else. This will act as a normal install, and will solve your boot problem because it will use a bootloader that will fit your USB MBR.

  • This is not what I want. A live USB install is not a normal install. Why would the MBR be too small? Is there a way to increase the size? Jun 20 '12 at 12:58
  • 1
    This is just wrong. the size of the MBR is always 512 bytes! May 3 '16 at 16:39

I would use UNetBootIn in order to make the USB drive bootable with Lubuntu.

EDIT: From the DamnSmallLinux Wiki

"Some users have mentioned that grub-install whines about the --no-floppy argument. Try going without it, try going with it, try using sudo, try unplugging and replacing your USB stick. If your system auto-mounts the USB stick, try it with the stick both mounted and unmounted. You'll probably find a way to make it work."

  • 1
    I don't want a live USB install. I want a dedicated install to a USB drive. Doing the live install is easy. That's how I installed to the USB drive in the first place. Jun 20 '12 at 12:59
  • Expanded answer with some help from the damnsmalllinux wiki
    – darryn.ten
    Jun 20 '12 at 13:02

Here's how: 1. On the live Lubuntu disk open a partition manager (usually called "disks" or "Gparted").

  1. Now you must format your USB Drive to the MBR/DOS format. Delete any partitions that may remain on the drive. You can do a quick format.

  2. Create a FAT partition on the drive. The size of it should be at least 500 megabytes. Now do a format (once again, it can be a quick format) and select exFat as the filesystem.

  3. Now create two more partitions (EXT4 and SWAP) at your desired sizes.

  4. Run the installer, and at the part where it asks about where to install it, click manual. Select your drive at the top corner, then select each partition and change the usage as shown: exFat to boot partition; swap to SWAP Area; and EXT4 to EXT4 Journaling System.

It should install normally now. Hope this helps! Let me know if this doesn't work or you need more detail, as I am very willing to help.


I see your problem is genuine. As far as I understand you need a USB drive to use as a portable drive for OS.

For that you need to make a live usb from any tool like UnetBootin on one usb, lets say USB1. Then while booting from USB1 on PC add USB2 to your device. Then go for install and choose the USB2 as the partition for installing Lubuntu.

Hope this works out.

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