power loss in Ubuntu causes /ubuntu/disks/ to be empty on reboot

[Paul Sladen]

Ubuntu had been installed on an IBM ThinkPad X61T using Wubi ontop of the existing German-language Windows Vista operating system NTFS partition.

During a loss-of-power (direct, instant power-off by laptop) the Ubuntu root file system (inside the NTFS) was lost.

The boot loader now displays:

  find --set-root --ignore-floppies /ubuntu/install/boot/grub/menu.lst
  Error 15: File not found
  Press any key to continue.

Using 'c' for Command Line in the WinGRUB bootloader, then 'root' and using '<tab>' competition showed no 'root.disk' under '/ubuntu/'

A reboot into Vista (to cause a fsck of the NTFS partition) showed an /ubuntu/disks/ directory, but trying to open the directory silently failed.

Shutting down Vista and again using WinGRUB's '<tab>' completion now shows no 'disks/' anymore.

Possibly the only long-term way around this is to assemble a list of blocks making up the loopback file-system, construct a device-mapper device using these and unmount/remount re-only the NTFS base partition. (As long as no checksums are involved, this would mean that the raw data could still be written to disk through the 'stencilled' holes in the NTFS partition, but without the risk of leaving the NTFS partition in a state that Windows' journal replayer is unhappy with.

AFAICT, there's no equivalent to '/lost+found' on Windows; I'm wondering if there's some undelete method I can use (bare in mind that the GUI is all in a locale that I'm not great at reading!

[Agostino Russo (ago)]

Paul, did you try to run chkdsk?
Is there any hidden found.000* dir under C:\ or C:\ubuntu?

[KeithFisher (keith-j-fisher)]

I have had an identical experience to that outlined by Paul (Dell D630 with WinXP SP2 and Wubi).

[Kurt Pfeifle (pfeifle)]

I confirm the bug as described by Paul, with a few differences: first, I didn't see the "find..." boot loader display. Instead, I had the "grub>" prompt. However, his observation with the 'disks/' directory matches mine: it was still there initially.

After rebooting into Windows (XP Home in my case), there was no fsck initiated by Windows itself. But the disk/ directory was unaccessible, and Windows told me that it was somehow currupted.

I ran fsck manually. After that, no more a disks/ directory.

So I re-installed Ubuntu....

It was only 2 days later that I noticed the C:\hidden found.000* dir, which did include a "dir0000.chk" subdir, with the swap.disk and root.disk and the "boot" subdir.

So far, I did not yet have time to try and copy these files back to their original places to test if they'd still work.

[Agostino Russo (ago)]

The hidden found.000 directory is created when chkdsk is run. Whether you can recover any useful information from there depends on the damage. From the reports I received in the past, usually you can restore the files therein and then boot Wubi, but your luck may vary. Unfortunately there is little we can do on the Linux side once you have filesystem corruption in ntfs, other than informing the user via a panic message. At the moment the only way to fix things is by running chkdsk (or equivalent) from windows, and that might in some cases hide away the files. Hopefully fsck for ntfs will be available soon. If you have any suggestion, please post it.