[Xen-users] Re: domU corrupt after server crash, help needed trying to recover domU

[Rudi Ahlers <rudiahlers@xxxxxxxxx>]

On Fri, May 8, 2009 at 2:29 PM, Rudi Ahlers <rudiahlers@xxxxxxxxx> wrote:

Hi all,

One of our Dell servers has failed badly, and one of the domU's has been corrupted in the process. It boots up to a point and then gives me a kernel panic:

Loading dm-zero.ko module
Loading dm-snapshot.ko module
Scanning and configuring dmraid supported devices
Scanning logical volumes
  Reading all physical volumes.  This may take a while...
  No volume groups found
Activating logical volumes
  Volume group "VolGroup00" not found
Creating root device.
Mounting root filesystem.
mount: could not find filesystem '/dev/root'
Setting up other filesystems.
Setting up new root fs
setuproot: moving /dev failed: No such file or directory
no fstab.sys, mounting internal defaults
setuproot: error mounting /proc: No such file or directory
setuproot: error mounting /sys: No such file or directory
Switching to new root and running init.
unmounting old /dev
unmounting old /proc
unmounting old /sys
switchroot: mount failed: No such file or directory
Kernel panic - not syncing: Attempted to kill init!


It shows up as a Zombie:

[root@xen ~]# xm list
Name                                      ID Mem(MiB) VCPUs State   Time(s)
Domain-0                                   0     1439     1 r-----    329.0
Zombie-hfserver2                          15     1024     1 ----c-      0.5
hfdns02                                   10      519     2 r-----   1552.8


I can't mount either:

root@xen ~]# mount /dev/data/hf
hfdns02    hfserver2
[root@xen ~]# mount /dev/data/hfserver2 /mnt/cpanel/
mount: you must specify the filesystem type
[root@xen ~]# mount -o loop /dev/data/hfserver2 /mnt/cpanel/
mount: you must specify the filesystem type

Here's the output of the LVM partitions:

[root@xen ~]# lvscan
  ACTIVE            '/dev/data/cpanel002' [100.00 GB] inherit
  ACTIVE            '/dev/data/windows2003_web' [30.00 GB] inherit
  ACTIVE            '/dev/data/storage' [50.00 GB] inherit
  ACTIVE   Original '/dev/data/hfserver2' [30.00 GB] inherit
  ACTIVE            '/dev/data/hfdns02' [30.00 GB] inherit
  ACTIVE            '/dev/data/pluto' [30.00 GB] inherit
  ACTIVE   Snapshot '/dev/data/pluto_s' [30.00 GB] inherit
  ACTIVE            '/dev/system/root' [39.06 GB] inherit
  ACTIVE            '/dev/system/swap' [9.75 GB] inherit
[root@xen ~]# vgscan
  Reading all physical volumes.  This may take a while...
  Found volume group "data" using metadata type lvm2
  Found volume group "system" using metadata type lvm2
[root@xen ~]#           


Does anyone know how to fix a LVM like this?                                                          

--

 Here's what I've done so far:

[root@xen ~]# losetup /dev/loop4  /dev/data/hfserver2

# This mounts the LVM partition as imaginary physical to /dev/loop4

# data is the virtual group (VG) name

[root@xen ~]#  kpartx -va /dev/loop4

add map loop4p1 : 0 208782 linear /dev/loop4 63

add map loop4p2 : 0 62701695 linear /dev/loop4 208845

# This creates a device map with partitions in /dev/data/hfserver in /dev/mapper 

[root@xen ~]# vgscan

  Reading all physical volumes.  This may take a while...

  Found volume group "VolGroup00" using metadata type lvm2

  Found volume group "data" using metadata type lvm2

  Found volume group "system" using metadata type lvm2

[root@xen ~]# lvscan

  inactive          '/dev/VolGroup00/LogVol00' [27.94 GB] inherit

  inactive          '/dev/VolGroup00/LogVol01' [1.94 GB] inherit

  ACTIVE            '/dev/data/cpanel002' [100.00 GB] inherit

  ACTIVE            '/dev/data/windows2003_web' [30.00 GB] inherit

  ACTIVE            '/dev/data/storage' [50.00 GB] inherit

  ACTIVE   Original '/dev/data/hfserver2' [30.00 GB] inherit

  ACTIVE            '/dev/data/hfdns02' [30.00 GB] inherit

  ACTIVE            '/dev/data/pluto' [30.00 GB] inherit

  ACTIVE   Snapshot '/dev/data/pluto_s' [30.00 GB] inherit

  ACTIVE            '/dev/system/root' [39.06 GB] inherit

  ACTIVE            '/dev/system/swap' [9.75 GB] inherit

[root@xen ~]# lvchange -ay VolGroup00

[root@xen ~]# lvscan

  ACTIVE            '/dev/VolGroup00/LogVol00' [27.94 GB] inherit

  ACTIVE            '/dev/VolGroup00/LogVol01' [1.94 GB] inherit

  ACTIVE            '/dev/data/cpanel002' [100.00 GB] inherit

  ACTIVE            '/dev/data/windows2003_web' [30.00 GB] inherit

  ACTIVE            '/dev/data/storage' [50.00 GB] inherit

  ACTIVE   Original '/dev/data/hfserver2' [30.00 GB] inherit

  ACTIVE            '/dev/data/hfdns02' [30.00 GB] inherit

  ACTIVE            '/dev/data/pluto' [30.00 GB] inherit

  ACTIVE   Snapshot '/dev/data/pluto_s' [30.00 GB] inherit

  ACTIVE            '/dev/system/root' [39.06 GB] inherit

  ACTIVE            '/dev/system/swap' [9.75 GB] inherit

[root@xen ~]# e2fsck /dev/VolGroup00/LogVol00

e2fsck 1.39 (29-May-2006)

/dev/VolGroup00/LogVol00: clean, 631982/7325696 files, 4512772/7323648 blocks

At first it found a whole lot of damages inodes which I repaired.

Then, I reversed the process:

[root@xen ~]# lvchange -an VolGroup00

[root@xen ~]# lvscan

  inactive          '/dev/VolGroup00/LogVol00' [27.94 GB] inherit

  inactive          '/dev/VolGroup00/LogVol01' [1.94 GB] inherit

  ACTIVE            '/dev/data/cpanel002' [100.00 GB] inherit

  ACTIVE            '/dev/data/windows2003_web' [30.00 GB] inherit

  ACTIVE            '/dev/data/storage' [50.00 GB] inherit

  ACTIVE   Original '/dev/data/hfserver2' [30.00 GB] inherit

  ACTIVE            '/dev/data/hfdns02' [30.00 GB] inherit

  ACTIVE            '/dev/data/pluto' [30.00 GB] inherit

  ACTIVE   Snapshot '/dev/data/pluto_s' [30.00 GB] inherit

  ACTIVE            '/dev/system/root' [39.06 GB] inherit

  ACTIVE            '/dev/system/swap' [9.75 GB] inherit

[root@xen ~]# vgchange -an VolGroup00

  0 logical volume(s) in volume group "VolGroup00" now active

[root@xen ~]# kpartx -d /dev/loop4

[root@xen ~]# losetup -d /dev/loop4

[root@xen ~]#

[root@xen ~]# xm create -c /etc/xen/hfserver2

And then it dies:

 Reading all physical volumes.  This may take a while...

  Found volume group "VolGroup00" using metadata type lvm2

Activating logical volumes

  2 logical volume(s) in volume group "VolGroup00" now active

Creating root device.

Mounting root filesystem.

kjournald starting.  Commit interval 5 seconds

EXT3-fs: mounted filesystem with ordered data mode.

Setting up other filesystems.

Setting up new root fs

no fstab.sys, mounting internal defaults

Switching to new root and running init.

unmounting old /dev

unmounting old /proc

unmounting old /sys

exec of init (/sbin/init) failed!!!: No such file or directory

Kernel panic - not syncing: Attempted to kill init!

 [root@xen ~]# 

-- 
Kind Regards
Rudi Ahlers
CEO, SoftDux Hosting
Web: http://www.SoftDux.com
Office: 087 805 9573
Cell: 082 554 7532
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