recovering corrupt file system

[Stephen Samuel]

well, the next place to go, if fsck isn't enough would be to to try
debugfs(1)
man debugfs.

On Wed, Nov 18, 2015 at 8:39 PM, Boylan, Ross <Ross.Boylan at ucsf.edu> wrote:

> I guess some of the trouble was that the virtual disk was mounted
> read-only at the VM level.  When I mounted read/write I was able to do
> fsck, which gave messages about replaying the logs and a couple messages
> about changing the inode counts (sorry, don't have the exact words).  Then
> I ran fsck -f, which didn't report any problems.  Then I mounted it, and
> everything seems OK.
>
> I'm still interested in the general question about how to diagnose and
> recover from file system errors, since I have another virtual machine that
> was backed by a failing real disk.
> ________________________________________
> From: Boylan, Ross
> Sent: Wednesday, November 18, 2015 4:35 PM
> To: Ext3-users at redhat.com
> Subject: recovering corrupt file system
>
> Any recommendations for tools to diagnose and recover problems on an ext4
> file system?
>
> In particular:
> root at jessie01:~# mount -o ro /dev/markov02/root /mnt/markov02
> mount: wrong fs type, bad option, bad superblock on
> /dev/mapper/markov02-root,
>        missing codepage or helper program, or other error
>
>        In some cases useful info is found in syslog - try
>        dmesg | tail or so.
> and e2fsck says
> root at jessie01:~# e2fsck /dev/markov02/root
> e2fsck 1.42.12 (29-Aug-2014)
> /dev/markov02/root: recovering journal
> Superblock needs_recovery flag is clear, but journal has data.
>
> markov02/root is an LVM volume, built on partitions from 2 disks in a
> virtual machine.  The initial symptom was that the VM the disks were in
> originally would only get as far as busybox when it started.  However, I
> think the filesystem was OK even after that, since it was visible in
> busybox and in another VM.  I think virt-manager might have overwritten on
> of the disks because I left "allocate entire disk now" checked when I moved
> one of the disks between machines.
>
> I'm making copies of the virtual disks now.
> Ross Boylan
>
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-- 
Stephen Samuel http://www.bcgreen.com  Software, like love,
778-861-7641                              grows when you give it away
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