Ubuntu’s latest release – Interpid Ibex 8.10 – ships with a new feature that allows to install itself to a USB drive. This by no means is revolutionary since you could have done this earlier using software like Ubnetbootin, but bundling this feature with the distro itself adds a new dimension of ease to those who’re just trying out Ubuntu and might want to carry a secondary operating system in their USB drive. ‘Ease of use’ since unlike Unetbootin, you don’t have to download a distro or keep / create an ISO file; you can simply use any Ubuntu Live CD you already have. You can access this feature from System > Administration > Create USB startup disk. There is really nothing much you need to do, except plug-in your USB drive BEFORE you start this utility. Ideally, you should do this install on a formatted (clean) pen drive.
In the utility, you’ll find an option on how much disk space you want to allot for documents created in the USB disk session. I would suggest that you keep this amount to the minimum, because no matter whether the documents are there are not that much amount of specified space will always be occupied. Ubuntu makes a ‘persistence’ file called casper-rw with filesize equal to the amount you specify you want to reserve. I won’t get into the technical details, but the moot point is that without reinstalling Ubuntu you won’t be able to change this. You probably won’t create THAT much documents in a USB disk session to fill up the whole minimum amount. You should note, however, that the extra space after installing Ubuntu on your USB drive will NOT be available if you’re running in a USB Ubuntu session – but you can use the pen drive normally if you’re running Windows and / or Linux from hard disk / Live CD. Furthermore, any files that you create and store in the Ubuntu session will be stored in the casper-rw persistence file, and thus not available from Windows. (You can, however, save the files you create to the hard disk of the computer you’re using and retrieve it later using the USB drive.)
With the new USB install procedure you might run into some problems. First you need to ensure that you’re BIOS supports booting from USB drive, and that the boot priority for USB disk is set to higher than hard disk in your BIOS settings. I can’t give instructions for BIOS because it’s different for different manufacturers / makes, but I’m sure you’ll figure that out. The other (more ‘disturbing’) problem that you might encounter is after booting from the USB drive, your computer might throw up this error:
Invalid or damaged Bootable partition
This happens on only certain makes of BIOS and hardware, and isn’t actually anything scary. The solution for this is pretty simple:
- When you encounter the error message, force a shutdown by pressing down the power button.
- Power up, and pop the Ubuntu Live CD into your CD tray. Boot into the Live CD session.
- Plug-in your USB drive. Wait for it to be detected. If the system prompts you to auto-run the USB drive, press Cancel.
- Go to System > Administrator > Partition Editor. Wait for it to scan available media. When it does, switch the media to your USB disk from the dropdown box at the top right corner.
- Right click on the USB disk partition which shows up and choose Unmount. (I’m assuming that the disk is mounted; if it’s not you may skip this step.)
- After it has been unmounted, right click again on the partition and choose the option Flags. In the dialog box that open, boot would already be checked. Let that be, and check the box next to lba. Click OK.
- Apply any pending changes (if needed) by clicking the Apply button on top and close Partition Editor.
- You can now shutdown / reboot the Live CD session. Note about Ubuntu 8.10 live CD session: On some system configs, shutdown / reboot might not work properly. If you reach a screen with a blinking cursor at the top only, eject CD / unplug pen drive. Software already loaded onto RAM will encounter an error and then proceed with shutdown. This does not harm your system in any way.
Try booting from USB disk next time. It should work now. This is a bug in the USB creator in Ubuntu which doesn’t add the LBA (logical block addressing) flag – which is needed for bootable partitions of size more than 500 MB. A small error, but one which can scare the wits out of some newcomer to Linux who’s trying out stuff.
Everything else remains in the USB disk sessions runs pretty much like booting into a live CD, except that if you chose to keep the persistence file then any settings changes you make are also retained. I seriously suggest everyone to go ahead and create a USB startup like this. It can be very handy in recovering your precious data if your operating system crashes. Also a good idea to use a USB disk when you’re accessing the Internet / working on a public computer (say, a cyber cafe or library) for greater security.