I'm pretty new to linux and have only had a little exposure to it. From what I've seen I really like it.

What I've done is I have a laptop from my employer that I take with me on business trips. There isn't administrator rights on my account so I can't install much of anything. I'm an avid gamer without a gaming laptop and it kills me when I go on a trip and can't game. I had the idea to install ubuntu to my external hard drive since I can load steam and play my games on the go.

Everything was working great and I have my external hard drive booting into Ubuntu and thought I was well on my way to this idea working....

Problem is that it looks like my Windows partition (the internal hdd) won't boot unless my external hard drive is attached so it can use the bootloader (GRUB maybe?) from the external hdd.

Any help would be awesome. I don't really want to have to take my external drive in to my office just to select the windows partition to boot and i certainly dont want to ask our IT for help. Is it possible to directly boot into windows when the external hdd isn't connected and into the external hdd when it is connected?


If you have a CD/DVD of your Windows (The clean solution) :

  1. Boot from Windows CD/DVD and choose “Repair” when it shows up.

  2. Choose Command Prompt on the resulting screen and run the following two commands:

    bootrec /fixmbr bootrec /fixboot

  3. Remove the CD/DVD and you should boot straight into Windows

If you don't have the CD/DVD then use Ubuntu:

  1. if internet connectivity available, open a terminal and run these commands:

    sudo apt-get install lilo sudo lilo -M /dev/sda mbr

  2. If no Internet connection:

    Recent versions of Ubuntu include the file /usr/lib/syslinux/mbr.bin which is 440 bytes in length and simply needs to be written to the beginning of the mbr with this terminal command. WARNING! Be very careful with this command and check for typos before running it.

    sudo dd if=/usr/lib/syslinux/mbr.bin of=/dev/sda

  3. Now reboot, remove external HDD and you should reboot straight into Windows.

  • Will try this when I get back home. Currently on a business trip – Matthew E. Addison Aug 18 '15 at 23:04
  • Yes yes yes. This worked. Thank you so much!!!! – Matthew E. Addison Aug 19 '15 at 2:08

First you must boot into Ubuntu and run

sudo grub-install /dev/sda

and then you need to change your BIOS settings to boot to the internal drive first. That will put the GRUB bootloader on the internal drive.

On the other hand, you can just use your BIOS boot menu to select the internal drive during bootup.

  • This didn't work....still getting...... error: no such device and entering resue mode. Grub rescue> this is what I get when the external hdd is not connected – Matthew E. Addison Aug 18 '15 at 0:50
  • hmmm. Does your laptop have a second hard drive bay? – Daniel Aug 18 '15 at 16:50
  • If so, you could install the external HDD in that bay internally so you wouldn't have to lug it around. – Daniel Aug 18 '15 at 16:50
  • Can't really open and install internally as its a work laptop that is provided from my employer. – Matthew E. Addison Aug 18 '15 at 23:02
  • Ah. Have you considered perhaps installing Ubuntu on one of those micro size thumb drives? Those are small enough to leave in permanently, and you can get them up to like 128GB. – Daniel Aug 19 '15 at 14:29

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