read-only root and can't edit fstab

[doodude]

I don't know how it happened, but I was unable to boot into Ubuntu 9.1 today because the file system is now read only. When I check fstab, it shows "ro" but I can't change it because it's on a read only file system. I tried umounting the root then remounting with read/write access, but I was unable to umount the root. I also tried booting with a live CD, but all I can find is the root.disk file, I can't see any of the file structure. That's probably just how it is supposed to be, but I'm new to Linux so I found it strange.

Can anyone suggest another method to either change the disk to read/write besides this?

sudo umount /
mount -o remount,rw /

The other option would be to somehow mount the disk image while using a live CD so that I can get to the fstab file and (hopefully) edit it.

Thanks for any suggestions.

[darolu]

You won't be able to unmount "/" when you are using it to boot; you will have to make your changes using a LiveCD/bootable pendrive. The default options for "/" (fstab file) are "errors=remount-ro", so it only mounts read-only when erros are present, try running a file system check (booting from LiveCD, without mounting it) with e2fsck (change your device accordingly):

$ e2fsck /dev/sda1

[doodude]

Thanks for the suggestion. When I run a live CD and use the command you suggested, I get:
"Superblock invalid, tring backup blocks...
Bad magic number in super block while trying to open /dev/sda1
The superblock could not be read or does not describe a correct ext2 file system..."

When I look at GParted, the two file systems are both NTFS. I have a root.disk image file under /ubuntu/disks that is the size of the file system created when I originally installed ubuntu.

The disk has been failing (bad sectors) for months, so that maybe that's related to this problem, but I think it's probably something I changed without knowing when I was looking at the partitions before the problem started.

Is there a way I could mount that image file to get to the files while using the live CD? I really don't understand how ubuntu is residing on an NTFS partition... but again, I am a linux newbie.

Thanks

[klemes]

You don't describe your exact situation well enough for someone to be able to help you.
Did you install Ubuntu with Wubi or is it a native install?
What type of filesystem did you originally specify when you first installed Ubuntu?
What exactly is this image file you want to mount?Is it a backup?If yes how you acquired it(what tools did you use?)
Anyway a good place to start would be to start from Live CD as you did and type :

sudo fdisk -l

to see all available partitions in your hard drive.
and then run a sudo fsck /dev/sdxx according to what partition the previous command will point out as being your root partition.
Also if you are able to mount eventually your / partition it would be nice to show us the /etc/fstab file and the output of the blkid command though I doubt it it's a fstab problem rather being a hard disk failure as you also suspect...

[doodude]

I apologize for my ignorance here. I'll try to give some background:

I tried sudo fdisk -l and get the following results:

Device Boot Start End Blocks Id System
/dev/sda1 * 1 18650 149806093+ 7 HPFS/NTFS
/dev/sda2 18651 19457 648227+ 7 HPFS/NTFS

I installed from a live CD and I honestly don't recall what file system I setup at the time. Since neither of these partitions are ext3, maybe that means I used Wubi (though I never remembered seeing that term until you posted it).

As for the image file, I guess I'm trying to understand what's going on when I boot into Ubuntu and where that directory structure resides. When I attempt to boot normally and end up at a terminal after the GUI load fails and has several error messages about a read only file system.

The fstab file says this :

UUID=19E45XXXXXXXXXXXX /host ntfs-3g defaults 0 0
UUID=2CXXXXXXXXXXXXXXX / ntfs-3g users,ro 0 0

Thanks
(not actually X's, but I'm assuming that isn't important)

I've copied all the files I care about to a backup drive, so I might just do a new installation, but now I'm not sure how to even do that as the live CD didn't give me the option of installing without formatting the drive.

[louieb]

You have a WUBI (inside windows) install. Sorry - have not used it - it been said - easiest way to install Linux and the hardest to fix when things go wrong.

Perhaps this will help WubiGuide - Ubuntu Wiki

think this might be the section you want
https://wiki.ubuntu.com/WubiGuide#Ho...on%27t%20boot?