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Old 10-18-2011, 04:48 AM   #1
yangiss
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How to fix Grub rescue - "exception Emask" error?


Hi everyone!
Recently I installed ubuntu 11.04 (sda3) alongside Windows XP (sda1), on my ThinkPad T60.
However, last Saturday, while I was surfing on the Internet (youtube video), the computer suddenly crashed (it turned off, as if I had just plugged it off). When I tried to reboot, all I got was a ”error: unknown filesystem”, and the ”grub rescue” prompt. Navigating through grub rescue is impossible (for me at least!), since anything I do is followed by ”unknown filesystem”. All I can do is ”ls”, even ”ls /boot” won’t work.
After very little research I found out that I could use ubuntu on a cd/usb and replace/update grub from there.
So I prepared a USB key and started the computer. And here’s the error I get when booting from the USB:

ata3.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x0
ata3.00: irq_stat 0x40000008
ata3.00: failed command: READ FPDMA QUEUED
ata3.00: cmd 60/00:08:00:78:8e/00:00:06:00:00/40 tag 0 ncq 4096 in
res 41/40:00:00:78:8e/00:00:06:00:00/40 Emask 0x409 (media error)
ata3.00: status: { DRDY ERR }
ata3.00: error: { UNC }
ata3.00: configured for UDMA/100
ata3: EH complete

…on and on

(More on this problem here: http://ubuntuforums.org/archive/inde...t-1034762.html )

The solutions suggest it’s a kernel bud, which can be fixed by something like
"options libata noacpi=1" on /etc/modprobe.d/options

Another problem is that, even when I manage to get far enough in the installation to be able to use ctrl+alt+F1 (which is ONLY when I choose ”install on Hard Drive” from the USB), anything I modify is gone when I reboot.
And when I try to modify the starting options in the USB (noacpi, etc.), I get an error message saying ”can’t find kernel image”.

I then decided to run a HHD check to see if something’s wrong there, and I got this:
”Error code 0000: read verification failed” (My HD is a Fujitsu MHV2100BH)

I am definitely not an expert with Linux and this type of problems, and right now I’m completely out of ideas. (The last thing I can think of is opening the laptop and trying to move/replace the HD and see what happens)
Also, this is a fairly old computer (bought in 2006), so it’s not much of a loss if I have to get a new one, but it looks like this problem (”exception Emask…”) has happened on new HDs, and I certainly don’t want this to happen with a new one.

Do you have any suggestions on what to do next?
Thank you in advance for your replies! =)

PS: A couple of days before the computer crash, I got a message asking for an upgrade to ubuntu 11.10, which I did not do, but maybe the computer was updating something at the moment of the crash –but I doubt it since I didn’t ask for automatic updates and didn’t do it manually)
 
Old 10-18-2011, 08:43 PM   #2
krustybaguette
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Location: Olde Sturbridge MA
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re: How to fix Grub rescue

Quote:
Originally Posted by yangiss View Post
Hi everyone!
Recently I installed ubuntu 11.04 (sda3) alongside Windows XP (sda1), on my ThinkPad T60.
However, last Saturday, while I was surfing on the Internet (youtube video), the computer suddenly crashed (it turned off, as if I had just plugged it off). When I tried to reboot, all I got was a ”error: unknown filesystem”, and the ”grub rescue” prompt. Navigating
I run Linux Mint and Mine Debian and Win7 on a Lenovo Thinkpad X60 so our hardware is close cousins. When you describe a sudden crash do you mean the screen went black? or did it just "freeze?" Even if you literally unplugged it your battery (I assume you have one) should keep it running. So if the machine went black it sounds hardware related.

Have you tried booting from other media such as a Live CD or a USB stick? I've had problems where my grub seemed to get lost after using an external USB drive to boot into Windows 98...don't ask why? it's a long story. But just booting off a live CD and restarting seems to fix my grub issues. Can't explain it but "Super Grub CD" didn't work and running the live CD did.
 
Old 10-19-2011, 02:45 AM   #3
yangiss
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Thank you for your reply.

About the sudden crash> the screen went black (I don't have a battery anymore).

But I've made progress: instead of trying to boot from a USB and reinstall things from there, I just formated the entire HD with a live CD. I did lose the data, but at least I could reinstall Windows.

However, I tried to reinstall Ubuntu and was told it couldn't create an ext4 file system; the same error has appeared again, and upon a HDD check, I got ”Error code 0000: read verification failed” again. I don't know what to do. It seems to be a hardware problem, but Windows seems to be working normally.

PS: I love baguettes!
 
Old 10-20-2011, 09:42 AM   #4
krustybaguette
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My first thought is that there is still a problem with the MBR but before pursuing that line of thought I must ask: How were you attempting to create the partitions for Ubuntu? If you're using the Live CD, you might try getting GParted Live which can be run from a bootable CD or other devices.http://gparted.sourceforge.net/livecd.phpDon't forget to create /swap, root "/", and /home partitions

kb
 
Old 10-25-2011, 03:36 AM   #5
yangiss
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Quote:
Originally Posted by krustybaguette View Post
My first thought is that there is still a problem with the MBR but before pursuing that line of thought I must ask: How were you attempting to create the partitions for Ubuntu? If you're using the Live CD, you might try getting GParted Live which can be run from a bootable CD or other devices.http://gparted.sourceforge.net/livecd.phpDon't forget to create /swap, root "/", and /home partitions

kb
Well, I don't really understand what happened. Like I said previously, I formatted the entire HDD with a Windows CD, then installed it. After that, I used Ubuntu (on USB) and tried to install it as and ext4 journaling system, and it failed (I did not create a /home partition -I don't really understand what it is for nor how to use it- but I did create a swap, and did not forget root "/".

A couple of days later, I tried to install Ubuntu again with different partition sizes, thinking that maybe it was only a specific sector of the HDD that was damaged/unreadable, and now it works fine. I can't see any other explanations.
But I fear a similar problem might happen again. After all, I've had this laptop for more than 5 years now, I doubt it's going to get better.
If you think of any explanation, let me know, it might be helpful in the future, to me or to someone else.

Thank you anyway for your help. =)
 
Old 10-26-2011, 07:24 AM   #6
krustybaguette
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Question re: How to fix Grub rescue

Quote:
Originally Posted by yangiss View Post
Well, I don't really understand what happened...I tried to install Ubuntu again with different partition sizes, thinking that maybe it was only a specific sector of the HDD that was damaged/unreadable, and now it works fine.
Thank you anyway for your help. =)
Well if you're back up and running your dual boot that was the goal to begin with.

Quote:
(I did not create a /home partition -I don't really understand what it is for nor how to use it-
The /home partition is not absolutely necessary. When you install Linux a /home directory will be created for you. It will show as /home/username. But is recommended to have /home as a partition because in situations like you have just experienced it would be possible to avoid the loss of data. When you decide you have to reformat and reinstall,(because you can't boot into Linux) if you have a /home partition before you do that you can boot with a Live CD, or some other bootable utility like Universal Boot CD for Windows. Then you could copy the contents of the /home directory to some external media before reformatting your hard disk. Then once the data is safe in another location you go ahead with the reformatting. After it's up and running copy the /home directory back to the new installation.

I don't know if you can do it now but you might be able to use gparted to add a /home partition to an existing installation. If you do that you'd probably have to move or rename your current /home directory since the /home partitionwould have the same name in your file structure. I guess you could just move the /home/username directory to a safe place while adding the /home partition.

But don't do this before googling to see if it can even be done.

Ken
 
Old 10-26-2011, 11:33 AM   #7
widget
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You can, if you need to reinstall or even install a different Linux OS, use the same /home partition while formatting and install in a fresh / (root) partition. You do this by choosing the manual install option in the installer and just instructing the installer not to format the /home directory.

I, for instance, converted all my Ubuntu installs to Debian, leaving all the /home partitions in tact.

For that matter you can have several / (root) partitions all using the same /home partition although it is VERY important to use a different user name for each different OS using the /home. This is because of the configuration files in your /home/<user name> directory.

There are some other, rather complex, reasons why a /home partition is a good idea.

It is very possible to create one from a single partition installation. Ubuntu documentation has an excellent step by step (cut and paste commands) guide to doing just that. I ran through it once and it works very well. It does take some time.
https://help.ubuntu.com/community/Pa...ng/Home/Moving
 
Old 10-31-2011, 06:44 AM   #8
yangiss
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Thank you guys, it's very good to know!
But one question though: the /home partition needs to be quite big then, when you use lots of videos, music, photos, etc. Say you use 10GB of data in your /home/username/Desktop directory. Then you must have at least 10GB on your home partition, but you need that space on the root partition as well, right?
So isn't it kind of a waste of space for those of us who don't have a huge hard drive? (having an external hard drive saves all of my problems though =) )
 
  


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