Unknown Filesystem Boot Error

Asked by Cassandra Phillips-Sears on 2010-09-02

I have two ubuntu partitions on my HD. They are both karmic koala (10.4). Yesterday, on my sda/5 partition, update manager attempted to update some packages, but I got a bug, which is here:

https://bugs.launchpad.net/ubuntu/+source/grub2/+bug/628521

The computer went to sleep overnight and refused to wake with hotkeys or anything else, so I had to do a manual restart of my system this evening. When I turned on the computer (IBM T42) and went to boot the sda/5 partition, which has all my data on it and got the bug when upgrading yesterday, I got the following error:

error: no such device: 1cf9084e-f86b-447d-af7d-1a9db51dd094.
error: unknown filesystem
error: you need to load the kernel first.

press any key to continue...

I am going crazy! Can someone help? I have a boot CD but don't know if that will help here and would prefer not to lose all my data on that partition.

delance (olivier-delance) said : #1

Each partition has a UUID, which is a unique identifier, and Grub doesn't find the partition with the right UUID.
https://help.ubuntu.com/community/RecoveringUbuntuAfterInstallingWindows#Grub%202%20gives%20%22error:%20no%20such%20device:%20xxxxx.xxxxx.xxxxx.xxxx%22

Hi there, delance. Following your advice, I ran sudo update-grub2 from a terminal window within the partition that I could boot from.

However, now the option to dual-boot from sda/5 is gone; when I start up the machine the boot menu only shows the one partition (which is not the one on which my data was on) and the memtest options.

I installed GParted, which shows the following:

unallocated 1.0 MiB
/dev/sda1 ext 4 filesystem 13.97 GiB mount point /
/dev/sda2 extended filesystem 60.56 GiB
  /dev/sda2 has three more systems under it:
  /dev/sda7 ext 4 filesystem mount point /home 23.55 GiB
  /dev/sda 5 unknown 35.44 GiB
  /dev/sda 6 linux-swap filesystem 1.56 GiB

/dev/sda5 is the one I want. I want to keep the /home partition so I can move the files I want from /dev/sda5 to /dev/sda7 and reinstall the whole entire OS if I need to, without worrying about my files getting damaged, but first I have to boot up the /dev/sda5 partition!

The /dev/sda5 partition has a little warning sign next to it. When I view info for that partition, I get the following:

File system: unknown
Size: 35.44 GiB
flags: boot
path: /dev/sda5
status: not mounted
Label:
UUID:
First sector: 78686370
Last sector: 153019124
Total sectors: 74332755

Warning:
Unable to detect file system! Possible reasons are:
- the file system is damaged
- the file system is unknown to GParted
- there is no file system available (unformatted)

What to do?

delance (olivier-delance) said : #3

1) Checking disk
run command
   fsck /dev/sda5
which will check consistency of file system and try to repair it
2) bootloading chain and multiple Linux distro on same computer
The bootloading chain is made of:
a) the BIOS which read partition table
b) the MBR in choosen device, which will read boot sectors of partition which contains Grub
c) the boot sector of partition which will read the /boot directory
d) the /boot directory which will load one of its kernel, another one on another device or a second downloader
If you have two Linux installations, each isolated in its one "/" directory, you have two "/boot" directories. When you upgrade grub from one of them, you only upgrade the "/boot" of this one.
In fact, you need to have a dedicated partition for "/boot" directory, shared by all Linux distributions. So one upgrade done in one of them applies to all of them.

Please post when you have done fsck.

Hi, delance. I ran fsck /dev/sda5:

fsck from util-linux-ng 2.17.2
e2fsck 1.41.11 (14-Mar-2010)
fsck.ext2: Superblock invalid, trying backup blocks...
fsck.ext2: Bad magic number in super-block while trying to open /dev/sda5

The superblock could not be read or does not describe a correct ext2
filesystem. If the device is valid and it really contains an ext2
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 <device>

After running e2fsck -b 8193 /dev/sda5:
e2fsck 1.41.11 (14-Mar-2010)
e2fsck: Bad magic number in super-block while trying to open /dev/sda5

The superblock could not be read or does not describe a correct ext2
filesystem. If the device is valid and it really contains an ext2
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 <device>

Same thing. Any ideas?

delance (olivier-delance) said : #5

I have also heard of a software called Testdisk which could help, but never used it.

I'm trying Testdisk now and will post results when they're in.

Testdisk

Disk /dev/sda - 80 GB / 74 GiB - CHS 9730 255 63
Partition Start End Size in sectors
D HPFS - NTFS 0 1 1 4897 254 53 78686297
D Linux 0 32 33 1823 161 2 29294592
D Linux 809 1 1 2632 129 33 29294592
D Linux 809 162 58 2633 36 27 29294592
D Linux 811 140 34 2635 14 3 29294592
D Linux 813 20 40 2636 149 9 29294592
D Linux 813 85 41 2636 214 10 29294592
D Linux 1823 193 35 4897 252 27 49387520
D Linux 3147 103 29 6221 162 21 49387520
D Linux 3149 16 4 6223 74 59 49387520
D Linux 3151 188 46 6225 247 38 49387520
D Linux 3152 96 17 6226 155 9 49387520

I am currently trying to have testdisk find the backup superblocks for /dev/sda5.

It doesn't appear that there is a backup superblock according to testdisk. Should I just give up and go to a data recovery service at this point?

The original problem was in grub2; does anyone know why this got changed to testdisk?

delance (olivier-delance) said : #10

l did this to get attention of a testdisk expert, but i discovered nobody suscrided this package. You can revert to gparted if you want.

Thanks, delance. I will revert to grub2.

Can you help with this problem?

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