Tuesday, August 2, 2011

Missing the root.disk

I wrote earlier about the Mystery of the disappearing root.disk. I've seen a number of additional cases since that post - and not all have been catastrophic, so thought I'd discuss what the steps are to attempt recovery.

My belief is that this problem is largely the result of manually shutting down your computer when the Wubi install is hanging. But there have been cases where corruption has occurred without manual poweroffs and I've noticed that some files I delete from within Wubi are 'recovered' later by Windows.

But it is important for users to resist the urge to 'hit the restart/power button' when the Wubi install is hanging. For any OS this is a bad idea and can lead to problems. For Wubi installs it can be fatal. Instead refer to the Wubi Guide for other options.

The first thing you'll notice may be Windows running an automatic CHKDSK or when you try to boot Ubuntu you end up at a GRUB> prompt.
Then when you boot Windows and look in the C:\ubuntu\disks directory you'll notice the root.disk is missing. In some cases, the \ubuntu\disks directory is missing completely or is corrupted.

Running chkdsk
Depending on the problem, Windows may have run an automatic chkdsk or you may need to run it manually. It's not always necessary, but it will never hurt, so the first thing is to run it.
Go to My Computer on XP or Computer on Vista/7, right click the drive you installed Ubuntu on e.g. right click on C:, select Properties, select the Tools tab, then under Error-checking click Check now. Select to Automatically fix file system errors or Scan for and attempt recovery of bad sectors (I usually don't use this, but if you hard drive has problems it's a good idea). When the drive you installed on is C: the computer will tell you it has to schedule the scan for the next time you start your computer. Reboot to complete.


Locate recovered files/directories
The first thing to do is to look for the \found.000 folder on the drive in question i.e. C:\found.0000. This is hidden by default and (on my Windows 7 install) I also had to tell Windows not to "Hide protected OS files" just to see it. You may also have to recover from an administrator command prompt on Win7 (see below).

So now you look for your root.disk (or other .disk files) and copy them back to the \ubuntu\disks folder. If the entire \ubuntu\disks folder is missing, you'll likely find a dir0000.chk directory and within that the root.disk, swap.disk and empty \boot\grub folders. Copy this back to \ubuntu renaming the directory to disks.

If you're missing the root.disk but there is no file of that name, it may have been renamed chk0000.chk. Rename this to root.disk and copy back to \ubuntu\disks.

If the corruption was minor, then likely everything will work fine. If the corruption is major Windows may not even recover the root.disk at all.

Win7/Vista command line instructions
Hit the START key, enter CMD, then look above and right click on CMD.exe and select "Run as Administrator", as shown below. From Windows 8, type "CMD" on the Metro page, right click, and then look on the bottom for "Run as administrator.

Check for the hidden recovery directories: dir /a:h

Check each \found.??? directory:
C:\>cd \found.000
C:\found.000>dir
 Volume in drive C is OS
 Volume Serial Number is B4B7-99A8

 Directory of C:\found.000

19/07/2011  02:02 PM    15,000,000,000 file0000.chk
               1 File(s) 15,000,000,000 bytes
               0 Dir(s)  222,258,069,504 bytes free

C:\found.000>move file0000.chk \ubuntu\disks\root.disk
        1 file(s) moved.

Or if the whole \ubuntu\disks folder is missing:
C:\>cd \found.000

C:\found.000>dir
 Volume in drive C is OS
 Volume Serial Number is B4B7-99A8

 Directory of C:\found.000

19/10/2012  04:51 PM    <DIR>          .
19/10/2012  04:51 PM    <DIR>          ..
19/07/2011  02:02 PM    <DIR>          dir0000.chk
               0 File(s)              0 bytes
               3 Dir(s)  222,258,069,504 bytes free

C:\found.000>dir dir0000.chk
 Volume in drive C is OS
 Volume Serial Number is B4B7-99A8

 Directory of C:\found.000\dir0000.chk

19/10/2012  04:51 PM    <DIR>          .
19/10/2012  04:51 PM    <DIR>          ..
24/02/2012  12:22 AM    <DIR>          boot
06/11/2012  09:28 AM    13,000,000,000 root.disk
15/11/2011  09:28 PM       268,435,456 swap.disk
               2 File(s) 13,268,435,456 bytes
               3 Dir(s)  127,904,968,704 bytes free

C:\>move dir0000.chk \ubuntu\disks
        1 dir(s) moved.


I hope this helps you to recover your files. Remember to backup important data on your Wubi install. There's no reason to install important personal files on a root.disk - you can access them easily on the /host partition.

Updated 2012-11-06: added some more screenshots, enhanced DOS commands

42 comments:

  1. Perfect! Worked like a charm. Thanks!

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  2. thanks a lot. it works exactly right. for mine was dir0000.chk

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  3. wow thanks a million, worked... my whole final year project was on it, u saved me....p.s if u cant find the found.000 folder run chkdsk utility...after that it should appear...got a bit stuck there...

    ReplyDelete
  4. I seem to have the same problem with a missing root disk. This is confirmed via a bootlog report I generated recently and posted to the Ubuntu Community forums Wubi Megathread. However my Win7 installation is giving me no end of problems. Is there any way of doing this correction via Ubuntu 11.04?

    ReplyDelete
  5. PA Systems, you have to use chkdsk to repair ntfs corruption. There is no linux equivalent that I am aware of. If you cannot boot Windows, you can boot a repair CD (or the installation DVD) to a repair prompt, and run chkdsk from there.

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  6. you're the greatest! i ran into this problem several times, followed by a complete re-install of ubuntu. luckily this time i got your instructions. many thanks!

    ReplyDelete
  7. Hi...Here i am in a serious problem... i have installed ubuntu 11.10. with dual booting in windows xp. It's working fine but today morning i have tried to see the fedora 16 live cd through virtual box. after tried and power of the virtual box. i was try to boot ubuntu as normally. but i got the error message at booting time as

    GNU GRUB version 1.99-12ubuntu5

    Minimal BASH-like line editing is supported. For the first word, TAB lists possible command completions. Anywhere else TAB lists possible device or file completion.

    Here i can't log in ubuntu.
    please tell me what should i do...
    my lot some data's are inside the ubuntu...
    please help me...

    ReplyDelete
  8. Please post support requests to https://answers.launchpad.net/wubi/+addquestion
    and I'll try to help there. Thanks.

    ReplyDelete
  9. What happens if the file is not found?

    ReplyDelete
  10. Hi
    I have a problem in windows XP for ubuntu 11.10
    Error while booting is
    Try(hd0,0):NTFS5:error:"prifix"is not set

    confused a lot.how can I solve it?

    ReplyDelete
  11. If you cannot find the root.disk, then your Ubuntu install (and everything on it) is gone.

    Jitesh, the Try (hd0,0) and the "prefix not set" error are benign messages that happen on all installs. If it's not booting then the problem is likely the root.disk. Run chkdsk, confirm the root.disk is there, and try again.

    ReplyDelete
  12. Hi

    I am having the same problem as Jitesh...i hav run chkdsk and also my root.disk file is present...still showing the same issue

    ReplyDelete
  13. Had this error: Try(hd0,0):NTFS5:error:"prefix"is not set
    Im running Windows 7, last Wubi version with ubuntu 11.10, just found out after I get this error it seems the PC hangs but dont restart it, just let it work out alone for 5 minutes and it will ignore the error and go on

    ReplyDelete
  14. The 'error:"prefix"is not set' is a red herring that has nothing to do with any Wubi boot problems. For help with specific problems please refer to this

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  15. Thanks for this article, I have fixed my problem :)

    ReplyDelete
  16. yippie! this worked for me...

    @bcbc : you are really awesome , keep going
    thanks a ton

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  17. Thanks a ton! Really a life saver!

    ReplyDelete
  18. you saved my ass men! Great work, it works for me like cheese.

    ReplyDelete
  19. Hey BCBC...when I type the commands in my cmd prompt it says that the system cannot find the file specified..please help me...Im facing the same problem like all above

    Problem
    Try(hd2,0):NTFS5:error:"prifix"is not set

    ReplyDelete
    Replies
    1. Hi Akhiii, Please create a support request e.g. on questions.launchpad.net/wubi or ubuntuforums.org. The blog comments don't work well for support.
      Thanks,
      bcbc

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    2. thanks a ton

      Delete
  20. Thanks so much this really DID work!! was superb I couldn't find my found folder at first but on looking at the host files through a live cd or wubi install I found my "found" folder and inside there was my root disk!

    thanks so much, now have a good backup :)

    ReplyDelete
  21. hello every body
    i did the check disk on my c drive ...but i can't find the FOUND.000 folder
    even when i unchecked the option "Hide protected OS files"

    help me here !!

    ReplyDelete
    Replies
    1. You can check from a command prompt: CMD.EXE (select Run as administrator).

      Delete
  22. You're a life saver..thank you so much!!!!

    ReplyDelete
  23. It seems the root.disk may have been renamed to almost anything. How do I recognize it?

    I'm inspecting the folder found.001, and I see for example a subfolder called dir0000.chk that contains a lot of binary files with seemingly random hashed names.

    I expected to a find a single really big file, but there is none. Running du -h totals about 500Mb.

    ReplyDelete
    Replies
    1. That dir0000.chk is not the one you are looking for. If you are missing the \ubuntu\disks folder then there will be a dir????.chk with only the root.disk, swap.disk and boot directory. Chkdsk cleans up all sorts of corruption so there could be any number of unrelated files/directories. PS look at dates, and the root.disk is going to be > 5GB

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    2. And if you're not missing the \ubuntu\disks folder you're looking for a file named file????.chk that is >= 5GB. e.g. file0000.chk or file0001.chk etc. There are generally very few files > 5GB in size, so it shouldn't be difficult to identify the most likely candidate.

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    3. Thank you. Unfortunately my ubuntu is then lost, because there isn't a single file > 1GB.

      Delete
  24. This post saved my life yesterday. I thought I had lost all my files and oh God, I wanted to kill myself... So now I'll just say: THANK YOU SO MUCH.

    ReplyDelete
  25. in my case the root.disk is still there where it should be but it says the file size is 0 KB. Does this mean it has been totally wiped? I found this description of re mounting my root disk - would this work? http://neosmart.net/forums/showthread.php?t=5004

    ReplyDelete
    Replies
    1. In the reports I have seen, no one has recovered from this. I normally recommend a tool like photorec in this case as a last-ditch attempt to recover data, but I'm not sure whether photorec would work in this case (NTFS filesystem containing fragments of virtual disk containing datafiles). It might work (also if you have the patience to sift through a ton of unnamed, recovered files).

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    2. OK. sorry this is a stupid question, but does this mean none of the files or information saved on the ubuntu partition of my computer can be accessed at all? Ever?

      If so (and if I don't get forbidden from installing ubuntu ever again on work computers) do I simply re-install ubuntu somehow?

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    3. Everything used on a Wubi install is contained on the root.disk: the OS files and your data. If you haven't backed it up and the root.disk is gone, then, yes, so is your data. Wubi is not a good choice for a production system. It's okay to try out Ubuntu. If you choose to reinstall Wubi, then I recommend real-time synchronized data backups off the virtual disk (e.g. UbuntuOne or saved on another partition or the /host partition).

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    4. I found your ubuntuforums.org thread. I would advise against using boot-repair on Wubi. I have seen this happen a few times, and believe that fsck'ing a root.disk where there is NTFS corruption could result in problems. I don't have direct evidence, but my recommendation is: 1) Run chkdsk /f from Windows, 2) if necessary fsck the root.disk. Boot-repair will run fsck on the root.disk without recommending the user first run chkdsk on the NTFS partition.

      Delete
  26. Worked like a charm!!! Thanks

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  27. I have gone back to boot Ubuntu and I still get the same problem. grub> what should I do?

    ReplyDelete
    Replies
    1. You can fsck the root.disk (from a live CD) as described here.

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  28. why on earth if I run cmd (as administrator) all I get is "C:\Documents and Settings\" and not a single line more?

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  29. I recovered the files but the root.disk is 0 kb and I have the same error still. Any idea?

    ReplyDelete
    Replies
    1. I don't know of any solution for this. I would suggest running photorec to recover raw data if there's something critical you lost (I don't even know that this would work, but basically it's a last shot at recovery because the root.disk was too badly corrupted for chkdsk to fix it).

      Delete
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    ReplyDelete