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Grub rescue - error: unknown filesystem

My computer has (had) a dual boot of Ubuntu Precise and Windows 7. Recently, when I started the computer, grub gave me an error saying "Unknown filesystem", and sent me to grub rescue. I searched for solutions to this, and found this answer: Unknown filesystem error: grub rescue. I followed the instructions there, but they didn't really help: when I restarted the computer, it went straight to Windows without grub intervening at all (so it boots successfully, just not to the OS I want). This is the log from boot-repair. My Ubuntu partition is sda6.

Naturally, I'm a little worried, since the log says "unknown filesystem type ''", which to me looks like the partition might be corrupt somehow. From the Ubuntu Live CD, I started gparted and looked at my partitions, and it also told me that my sda6 is an unknown filesystem.

So my questions are basically:

  1. Can I restore Ubuntu to the way it was?

  2. If not, can I at least rescue the data I had on the partition somehow?

  3. Again, if I can't restore Ubuntu, how do I clean everything up so that I can reinstall it without too many complications?

Another thing I should mention is that yesterday I had a similar problem where the computer told me there was a problem with the hard drive when it was starting, but it fixed itself by running fsck (that time it got past grub, and managed to start Ubuntu). Between that occasion and me having trouble booting the computer today, I have booted it successfully at least twice.

Thanks for any help!

EDIT: Since I got the popular question badge for this, I might as well add for anyone looking that the computer's hard drive was just broken and I had to replace it. I guess it was unsalvageable.

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marked as duplicate by jokerdino, devav2, con-f-use, Jorge Castro, Tom Brossman Oct 31 '12 at 12:47

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.

    
I linked to that question in mine, it doesn't solve my problem –  Ben Oct 16 '12 at 1:57

1 Answer 1

up vote 1 down vote accepted

I saw the boot-info you provided.

This is an attempt to fix the corrupted filesystem

Possible data loss!!

You can apply this Only when you haven't any other options to rescue your data or to fix the problem

Boot from a LiveCD/Usb of Ubuntu. Open a terminal and do

sudo mke2fs -n /dev/sda6 

The /dev/sda6 partition is the partition where Ubuntu was installed and now is corrupted.

Above command will provide you with a list of Superblock backups stored on blocks

Take one number from there (usually the first one) and then apply bellow command

sudo e2fsck -y -b block_location /dev/sda6

Where block_location replace it with the (first) number from the results of Superblock backups stored on blocks

When this finish , run the boot-repair program and select the [Recommended Repair] option.

If everything else fails

As a last resort you can re-install Ubuntu without format the partition. After all is about what ? 10-15 minutes. Boot from LiveCD-Usb and select install. Then at the installer window click on "something else" and then take a look at these two pictures and you will figure out what you must do.

installation

installation2

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Thanks! When you say "possible data loss", does that mean I might lose the whole partition? Or part of it? –  Ben Oct 16 '12 at 2:24
    
And when you say I should apply it only when I have no other options, do you think it's likely that something else will come up? Or do you think this is my best bet? –  Ben Oct 16 '12 at 2:24
    
Your filesystem is already corrupted. If you see the boot-info says "Unknown filesystem". When you repair a filesystem always the danger for data loss is there. I cannot guarantee anything.You can wait if you want for a better answer. –  NikTh Oct 16 '12 at 2:26
    
I followed your advice. I think it helped, but now there's a problem with grub: it takes me to the menu "GNU GRUB version 1.99-21ubuntu3.4" with "minimal bash-like line editing is supported". it won't load from the livecd anymore –  Ben Oct 16 '12 at 4:01
    
It must be load from the liveCD/Usb. This has nothing to do with the OS. Its BIOS settings.I am almost certain that if you manage to boot from the live-cd and run the boot-repair again , your problem will be solved. –  NikTh Oct 16 '12 at 4:18

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