Maybe it also happened to you: One day you try to start up your Ubuntu 10.10 installation and end up with a busybox console and no chance to get to your desktop nor your data. First reflex to most: Boot from a Ubuntu Live CD and look what's going on. I did that and ended up with a stalling file browser when just trying to mount it by clicking on it, a stalling command shell when trying to mount it manually. Next step: Filesystem check of the supposedly faulty partition, but after trying to start it I got the message: fsck.ext4: Device or resource busy. After struggling for a bit and making it work again I decided to write this HowTo with some extra steps, so everybody can fix this special issue.
Ultra Short Version:
- Reason for the problem: bug in current version of fsck
- Fix: Boot from older Ubuntu Live CD and do a filesystemcheck as before.
Longer, More Relaxing Version:
1. Calm down!
Seriously, this is really the most important step: Don't Panic! When you stay in this mood and just start doing something just for the sake of doing something, chances are that you make things worse and end up with a real unrecoverable system. Try to remember that you sit in front of a linux system that worked the day before it is nearly impossible that all data is gone by the next day. Furthermore: a system that doesn't boot doesn't automatically mean that all your data is lost, too. If your problem seems to be the one described above, you'll be up and running again in a bit.
2. Understanding what's going on, choosing the right Ubuntu CD
The problem I ran into has to do with a bug in the latest fsck version, described here:
Normally a filesystem check is done on startup without any problems, in this special case/because of this bug this isn't possible and so the system falls back to a busybox on startup. Since this bug is existing in fsck on the Ubuntu 10.10 Live CD, too, you'll end up with the exact same scenario as on bootup. The only solution: Use an older Ubuntu CD, like Ubuntu 10.04 or 9.10. The only limitation downward is connected to the filesystem you try to fix, if it is the latest ext4 you can't go deeper than 9.04, since in older versions fsck plainly doesn't know ext4 and therefore won't be able to fix it. Note that of course all older versions of other linux distributions with older versions of fsck and the same limitations how far you can go back are in state of fixing this issue, too.
3. Getting the right Ubuntu CD and fixing the Problem
Hopefully you got an Ubuntu CD with a older version than 10.10 lying around somewhere, otherwise you'll have to get hold of a computer with internet access and a cd burner, and have a blank cd ready.
Click on this link to be forwarded to the nearest (and most of the time therefore quickest) server to your location. http://www.ubuntu.com/start-download
- Click on the Folder 9.10 to be sure, nevertheless 10.04.2 should also still be ok
- In the first section with the headline "Desktop CD" click on (Intel x86) desktop CD, a .iso file should now start to be downloaded.
- With your favourite CD burning application burn this image to a CD, e.g. with brasero, that comes standard with ubuntu: Start Brasero by clicking in the menu Applications/Sound & Video/Brasero Disc Burner, Choose Burn Image, Select the Image you just downloaded and burn it.
- alternatively you can install this iso to a USB-Stick on a not to old Ubuntu system by going to System/Administration/Startup Disk Creator. Note that by this process all data on the USB Stick will be erased that there are still a lot of older systems around that can't boot from USB sticks, and also some newer that doesn't support it.
4. Getting your system up and running again
- Insert the CD you just burned or the USB Stick you just set up, boot the system from it, if it doesn't work automatically try hitting the Escape (ESC) key on your keyboard during startup to bring up the bios' boot device selection. When this doesn't work for you try to find out which key to hit by referring to your mainboard's user manual.
- Choose "Try Ubuntu" when asked and wait for the Desktop to come up. I found that sometimes closing this window and choosing "quit installation" works if on the same system clicking "Try Ubuntu" only results in stalling.
- Just to calm you down a bit, check whether your data is still fine by going in the menu to Places and clicking on the drive you couldn't access earlier. Note that after having down this you have to unmount the device again for the next steps, e.g. by clicking the eject button on the left in the filebrowser you just opened by clicking on the drive in Places.
- Open up a console and find out which filesystem you want to fix by entering: sudo fdisk -l
- Assuming the filesystem you want to fix is /dev/sda1 enter the following for letting it be fixed:
sudo fsck -y /dev/sda1 (the -y means that every question will be answered with yes, so you don't have to hit y for the next 10 minutes)
DONE! After the file system check is finished restart your system, everything should work again.