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USB stick with Ubuntu Live system doesn't boot - why?

Posted 01-19-2011 at 04:17 AM by bittner
Updated 01-19-2011 at 04:39 AM by bittner

Tags boot, live usb, ubuntu, usb memory sticks

Creating an installation stick with Ubuntu seems to be a piece of a cake nowadays. Ubuntu does provide a tool, the "Startup Disk Creator" (System > Administration > Startup Disk Creator) which frees novice Linux users from knowing operating system level details. At least it seems.

I regularly notice, either in my Linux courses or in discussions with other proficient Linux users, that the tool on Ubuntu typically doesn't make sticks boot out-of-the-box. Usually, this has one of the following two reasons:

Bootable flag: The bootable flag of (the partition holding the Linux system of) your USB stick is not set.
BIOS settings: Booting from USB devices is not enabled on your computer.

Setting The Bootable Flag

Most users won't notice the first sentence on top of the Startup Disk Creator's main screen:

Quote:

To try or install Ubuntu from a removable disk, it needs to be set up as startup disk.

Aha, great. Sounds unspectacular. Though, translated into technical terms this says: "You have to have the bootable flag set on (the installation partition of) your removable disk." You can use the fdisk tool in a terminal window to check whether this is already the case:

Code:

~$ sudo fdisk -l
Disk /dev/sda: 80.0 GB, 80026361856 bytes
255 heads, 63 sectors/track, 9729 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
 
   Device Boot    Start       End    Blocks   Id  System
/dev/sda1   *         1      3147  25712032+  83  Linux
/dev/sda2          3148      3264    939771   82  Linux swap

Disk /dev/sdb: 8048 MB, 8048869376 bytes
141 heads, 58 sectors/track, 1922 cylinders
Units = cylinders of 8178 * 512 = 4187136 bytes

   Device Boot    Start       End    Blocks   Id  System
/dev/sdb1             1      1922   7859029   83  W95 FAT32

In the above example /dev/sdb is the USB drive, and we can see that there is no asterisk in the "Boot" row, hence the bootable flag is not set. Again, with fdisk, this time interactively, we can set the bootable flag of /dev/sdb using the "a" command:

Code:

~$ sudo fdisk /dev/sdb
Command (m for help): a
Partition number (1-4): 1

Command (m for help): w
The partition table has been altered!

Calling ioctl() to re-read partition table.

As soon as you have fixed this problem you can use the Startup Disk Creator to copy the Ubuntu Live system on your stick, and you should be all set.

Getting Your BIOS Settings Right

If your USB stick is bootable, but your computer still refuses to boot from it (and directly boots the system installed on your harddisk) you have to fix your BIOS settings:

Power off your computer, attach your USB stick, and power the computer on again.
Wait until you see a message saying "Press Escape to ...", or "F11 for startup options", or something similar. Press this key on your keyboard to interrupt regular booting.
Go into the BIOS settings, look out for "Boot sequence", and set the boot sequence such that any USB disks are consulted before your regular harddisk for booting. (Every BIOS is different, so it doesn't make sense to show you more details here, but there are nice blogs and howto's with screenshots on the internet that help you with that.)
Some more recent notebooks allow you to select the boot device from the startup menu only once for a boot time. You may prefer this instead of changing the general behavior in the BIOS.

Now booting from your Ubuntu Live USB stick should work!

If you still have problems getting it to work, drop me a note (comment on the blog), or try UNetbootin as an alternative to Ubuntu's Startup Disk Creator.

References

fdisk man page (partition table manipulator, user manual)
Create a bootable Ubuntu USB flash drive (with instructions for BIOS configuration)
UNetbootin (a more flexible boot device creator tool)
Live USB Pendrive Persistent (lengthy howto with several different solutions)

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	I just formatted removable disk as fat32 boot from Ubuntu live. Reboot to physicaly remove thumb drive and return to 'Try' option before you insert disk into usb or slot to mount file system or ubuntu will ask to boot from serial drive2. From System Administration choose Create Boot Disk, format and set rw space to allow room for updates. First attempt gave disk full error.
	Posted 01-21-2011 at 02:39 PM by grizlbr

Quote:

Originally Posted by grizlbr

I just formatted removable disk as fat32 boot from Ubuntu live. Reboot to physicaly remove thumb drive and return to 'Try' option before you insert disk into usb or slot to mount file system or ubuntu will ask to boot from serial drive2. From System Administration choose Create Boot Disk, format and set rw space to allow room for updates. First attempt gave disk full error.

Was that a question? Is there anything I can help you with? Have you tried step-by-step what I described above?

Posted 04-16-2012 at 07:21 AM by bittner bittner is offline

	THANK YOU! THANK YOU1 I'd been beating my head against the monitor and trying every version of creating an Ubuntu boot usb drive. You were absolutely right that the "small print": needs to be set up as an installable drive is totally useless without some of idea of how one makes an installable drive. I followed your steps here and it worked like a charm.
	Posted 11-20-2012 at 08:03 AM by drkitty

Quote:

Originally Posted by drkitty

THANK YOU! THANK YOU1 I'd been beating my head against the monitor and trying *every* version of creating an Ubuntu boot usb drive. You were *absolutely* right that the "small print": needs to be set up as an installable drive is totally useless without some of idea of *how* one makes an installable drive. I followed your steps here and it worked like a charm.

Glad it helped!

Posted 11-21-2012 at 04:54 AM by bittner bittner is offline