Re: badly destroyed XFS (on LVM) - how to repair?

[Eric Sandeen <sandeen@sandeen.net>]

On 5/12/12 7:49 AM, Michael Monnerie wrote:
> (This might be an LVM problem, but who knows?)
> 
> I have here an XFS that was on a server running within a XenServer 
> machine. In the end it existed of 4x 2TB disks:
> # pvscan 
>   PV /dev/xvdg   VG sharestore   lvm2 [1.95 TiB / 0    free]
>   PV /dev/xvdf   VG sharestore   lvm2 [1.95 TiB / 0    free]
>   PV /dev/xvdc   VG sharestore   lvm2 [1.95 TiB / 0    free]
>   PV /dev/xvde   VG sharestore   lvm2 [1.95 TiB / 0    free]
>   Total: 4 [7.81 TiB] / in use: 4 [7.81 TiB] / in no VG: 0 [0   ]
> 
> Then by accident the admin made "fdisk /dev/xvdg", created a partition
> like this:
> Platte /dev/xvdg: 1073 MByte, 1073741824 Byte
> 139 Köpfe, 8 Sektoren/Spuren, 1885 Zylinder
> Einheiten = Zylinder von 1112 × 512 = 569344 Bytes
> Disk identifier: 0xb30cf4db
> 
>     Gerät  boot.     Anfang        Ende     Blöcke   Id  System
> /dev/xvdg1               1        1886     1048448   82  Linux Swap
> 
> (partittion starting sector 63), and did "mkswap /dev/xvdg1". After a 
> reboot, LVM did not recognize the full disk anymore.
> 
> # pvscan 
>   Couldn't find device with uuid 396XfX-EbMZ-0J6q-C3bj-3n6d-vruJ-6Oiy7w.
>   PV unknown device   VG sharestore   lvm2 [1.95 TiB / 0    free]
>   PV /dev/xvdf        VG sharestore   lvm2 [1.95 TiB / 0    free]
>   PV /dev/xvdc        VG sharestore   lvm2 [1.95 TiB / 0    free]
>   PV /dev/xvde        VG sharestore   lvm2 [1.95 TiB / 0    free]
>   Total: 4 [7.81 TiB] / in use: 4 [7.81 TiB] / in no VG: 0 [0 
> 
> This is where I jumped in. I must say that in the meantime the source VM 
> got deleted, and that I only got access to the data disks. I believe 
> /dev/xvdg was the very first of those LVM disks before, but I'm not 
> sure.
> 
> I tried "pvcreate --uuid 396XfX-EbMZ-0J6q-C3bj-3n6d-vruJ-6Oiy7w --
> norestorefile /dev/xvdg", which did not succeed.
> Then I made a backup of the first sectors of /dev/xvdg, and did
> "dd if=/dev/xvdf of=/dev/xvdg bs=512 count=63", and tried again with
> "pvcreate --uuid 396XfX-EbMZ-0J6q-C3bj-3n6d-vruJ-6Oiy7w --norestorefile 
> /dev/xvdg" - this time it worked. Strange thing: /dev/sharestore/public 
> is not created, it's only accessible via /dev/dm-0, but 
> I can mount the XFS but it's destroyed, "ls" shows:
> ls: cannot access /1/hope: Invalid argument
> ls: cannot access /1/jog: Invalid argument
> ls: cannot access /1/maza: Invalid argument
> ls: cannot access /1/public: Invalid argument
> ls: cannot access /1/upload: Invalid argument
> ls: cannot access /1/du.old: Invalid argument
> ls: cannot access /1/.fsr: Invalid argument
> total 45

Anything in dmesg?

> drwxrwx---  17 root       1000 4096 May  1 00:00 ./
> drwxr-xr-x  25 root    root     632 May 12 12:42 ../
> ???????????  ? ?       ?          ?            ? .fsr
> drwx------   7    1007 nogroup 4096 Oct 19  2010 anse/
> -rw-r--r--   1 root    root     951 Jan  1 00:10 du.20120101
> -rw-r--r--   1 root    root     456 Feb  1 00:10 du.20120201
> -rw-r--r--   1 root    root     455 Mar  1 00:11 du.20120301
> -rw-r--r--   1 root    root     464 Apr  1 00:06 du.20120401
> -rw-r--r--   1 root    root     464 May  1 00:00 du.20120501
> ???????????  ? ?       ?          ?            ? du.old
> -rwx------   1 root    root     253 Nov  7  2010 find-inode.sh*
> ???????????  ? ?       ?          ?            ? hope
> drwxrwxr-x+  4    1007 nogroup   49 Nov 29  2009 itm/
> ???????????  ? ?       ?          ?            ? jog
> drwx------   6 makedns nogroup 4096 Aug 24  2010 lama/
> ???????????  ? ?       ?          ?            ? maza
> drwx------   2    1008 nogroup   68 Jan 12  2010 paan/
> ???????????  ? ?       ?          ?            ? public
> drwxrwxr-t   5 root    www     4096 Mar 17 11:33 tmp/
> drwxr-xr-x   2 nobody  root     144 Mar 17 11:41 torrent/
> ???????????  ? ?       ?          ?            ? upload
> drwx------   2    1003 nogroup   88 Nov 23  2009 vop/
> 
> Then I made a xfs_metadump, and xfs_repair, both with version 3.0.1, 
> which seems to not work. xfs_repair said this:
> 
> # xfs_repair -n /dev/dm-0 2>&1|tee xfs.log
> Phase 1 - find and verify superblock...

...

> No modify flag set, skipping filesystem flush and exiting.
> 
> So it found no error. I then installed xfsprogs 3.1.8, and tried the 
> repair on the metadump:
> 
> # xfs_repair xfs.metadump

You have to mdrestore the metadump before you can point repair it it, so that's not a valid operation.  No 

<later>

> Seems like it's an XFS problem - could someone help me here?

Considering that the problem began when the block device got
repartitioned etc, I don't see how this can be an XFS problem...

-Eric


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