Ubuntu – Install Ubuntu to USB 3.0 external drive

bootdual-bootgrub2hard drive

Yes I am trying to install Ubuntu to a USB external hard drive. I partition the drive and I put down install grub to the external hard drive so I did change this but for some reason it keeps installing grub to the internal drive. I'm trying to do this with 16.10 and I'm getting a little frustrated. I've tried to install it like three or four times and I keep telling it to install grub to the external drive but for whatever reason it wont do it. Can Ubuntu not be installed to a USB external drive?

This is an external hard drive not a small USB pin drive. Just to make this clear.

Best Answer

It works like that in UEFI mode. It 'wants' to use the existing EFI partition in the first drive (usually the internal drive /dev/sda).

But if you unplug or disconnect the internal drive (and have no extra drive connected), the installer will be happy(?) to install grub into your target drive, the USB external hard drive. That is how I do it.

Installing Grub to an external hard drive that has Ubuntu installed

Boot into an Ubuntu live USB and connect the external hard drive.
List partitions of all devices:
```
 lsblk
```
From the results of lsblk, identify the linux partition and also the efi partition of the external hard drive, i.e. /dev/sdXY1 and /dev/sdXY2 respectively. Replace XY1 and XY2 with your own partition names.
Special mount the linux partition:
```
  sudo mount /dev/sdXY1 /mnt
```

Mount critical virtual filesystems:

 for i in /dev /dev/pts /proc /sys /run; do sudo mount -B $i /mnt$i; done

chroot into the Linux partition you mounted:
```
 sudo chroot /mnt
```
You are now in the external hard drive's linux filesystem.
Create the directory where grub would install its files:
```
 mkdir -p /boot/efi
```
If it already exists, then skip to step 8.
Mount the efi partition from step 3:
```
 mount /dev/sdXY2 /boot/efi
```
Install grub to the external hard drive:
```
 grub-install /dev/sdX
```
Update grub:
```
update-grub
```
Find the UUID of the efi partition (aka 'vfat') and note it down:
```
blkid
```
or
```
ls -l /dev/disk/by-uuid
```
Now we need to tell fstab to mount that efi partition on boot:
```
cp /etc/fstab /etc/fstab.bak  
sudo nano /etc/fstab  
```
Add the below two lines to fstab replacing xxxx-xxxx with the UUID from step 11:
```
#my modified fstab to mount external hard drive's esp  
UUID=xxxx-xxxx   /boot/efi   vfat   umask=0077   0   1  
```
Make sure to comment out the fstab entry of the Windows esp so it doesn't conflict.
Exit the chroot:
```
exit
```
Reboot the PC:
```
sudo reboot
```

At this point when you reboot and choose your external device from the EFI boot manager, it will boot to grub.

To make Ubuntu automatically boot when you insert the external and Windows to automatically boot when the external is not inserted you would have to create a custom boot entry for Ubuntu to point to the efi on the external drive:

Creating a custom boot entry for Ubuntu to point to efi on the external HD

From Windows EasyUEFI can add or remove boot entries.

From Linux efibootmgr can add or remove boot entries.

Alternative #1 – using EasyUEFI

In Windows download EasyUEFI, install it and run.
Choose the EFI options manager
Choose create 'new entry' with + sign
Choose Linux or other OS and give it a name in the description box
Select the FAT32 EFI partition on the external drive that contains the grub bootloader
Choose browse
Navigate to /efi/ubuntu/shimx64.efi or /efi/ubuntu/grubx64
Save
Move it to the top of the boot entries list
Restart

Alternative #2 – using efibootmgr

List boot menu entries:
```
 efibootmgr
```
Create a boot entry:
```
 efibootmgr -c [-L label] [-d /dev/sdX]
```
e.g.: efibootmgr -c -L myubuntu -d /dev/sdX

This boot entry would automatically be the first entry.

/dev/sdX is the external hard drive with the grub bootloader.
You can now reboot and without your intervention Ubuntu would automatically boot when external hard drive is plugged in. When the external hard drive is not plugged in, the PC would skip our Ubuntu boot entry to the next entry which is probably Windows Boot Manager.

Ubuntu – Installing Ubuntu on External Hard Drive – UEFI

I believe the installer now works with secure boot on. If not, the installed Ububtu will. So, turn secure boot back on after installing.

If you want the external to be bootable in any computer, then you have to make an EFI partition on it. Select something else for install to be sure the installer uses the external ESP not the internal. The EFI partition should be 500 MB, formated FAT, and flagged ESP.

If it will only be used on this computer, then using the internal drives EFI partition is preferable. Grub will require that the drive be connected so it can find it's config file. Though if you use the previous setup, it can be made so the computer automatically boots linux when the drive is connected or windows when not by setting boot order.

a separate /boot partition is unnecessary, and can cause problems if made too small

Edit:

as per Microsoft Secure Boot Documentation --- After disabling Secure Boot and installing other software and hardware, it may be difficult to re-activate Secure Boot without restoring your PC to the factory state

What this means is:

If you turn off secure boot in order to install low level software (such as drivers) in Windows, then turn secure boot on, Windows may not boot if the software is not signed by Microsoft.

Best Answer

Related Solutions

Ubuntu – How to install Grub in an external hard drive

Installing Grub to an external hard drive that has Ubuntu installed

Creating a custom boot entry for Ubuntu to point to efi on the external HD

Ubuntu – Installing Ubuntu on External Hard Drive – UEFI

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