After a power failure, I had the following error:
error: unknown filesystem
grub rescue>
I ran the Ubuntu repair using a live usb. The log can be found here
After this grub disappeared (I cannot select which OS to boot) and by default I am booting windows now. I have an important application running on Linux but I cannot boot to Linux.
I then edited the grub file and tried to update-grub but it says:
failed to get canonical path of /cow
The next option was to
sudo mount /dev/sda5 /mnt
But then I get the error:mount: you must specify the filesystem type
I do not know the filesystem type, since I did not do the installation on this particular machine.
I also tried
cat /etc/fstab
but it does not show sda5, neither can I see it usingblkid
command. From the GUI (since i have booted the system from live usb), I can see the partition 5 as having unknown type.
UPDATE: fsck -a -t ext4 /dev/sda5
immediately gives the following error:
fsck from util-linux 2.20.1 fsck.ext4: Bad magic number in super-block while trying to open /dev/sda5 /dev/sda5: The superblock could not be read or does not describe a valid ext2/ext3/ext4 filesystem.
If the device is valid and it really contains an ext2/ext3/ext4 filesystem (and not swap or ufs or something else), then the superblock is corrupt, and you might try running e2fsck with an alternate superblock: e2fsck -b 8193 or e2fsck -b 32768