Re: How to fix bad superblock or xfs_repair: error - read only 0 of 512 bytes

From: Eric Sandeen <sandeen@sandeen.net>
To: Christian Kildau <lists@unixhosts.org>
Cc: xfs@oss.sgi.com
Subject: Re: How to fix bad superblock or xfs_repair: error - read only 0 of 512 bytes
Date: Mon, 23 Jan 2012 22:51:21 -0600	[thread overview]
Message-ID: <4F1E38C9.3070000@sandeen.net> (raw)
In-Reply-To: <A7348842-BA7C-474A-B2E1-04345761AB25@unixhosts.org>

On 1/21/12 4:03 AM, Christian Kildau wrote:
> Hello,
> 
> I'm having some very serious issues with XFS after upgrading from a
> Linux Distro running Ubuntu 2.6.32 to 3.2.
> 
> It seems like my filesystems are damaged after attaching them to a
> Linux 3.2 server. I am also no longer able to mount the hdd on the
> old server that is still running 2.6.32!

did you do anything else at all besides simply boot a 3.2 kernel?

Or was this a whole distro upgrade?  And who knows what the installer
did...?

> 'test disk' does find the filesystem as XFS 4 and i created a 1.5TB
> dump of it to another hdd.
> 
> (I created the xfs filesystem on the entire hdd, not on a partition,
> so /dev/sdd is not a typo)

is sdd a single disk or something like lvm/md?

what does grep sdd /proc/partitions say?

And

# xfs_db -c "sb 0" -c "p" /dev/sdd

> 
> $ sudo mount -t xfs /dev/sdd /media/
> mount: /dev/sdd: can't read superblock
> (dmesg)
> [236659.912663] attempt to access beyond end of device
> [236659.912667] sdd: rw=32, want=2930277168, limit=2930275055
> [236659.912670] XFS (sdd): last sector read failed
> 
> $ sudo xfs_check /dev/sdd
> xfs_check: error - read only 0 of 512 bytes
> 
> $ sudo xfs_repair /dev/sdd
> Phase 1 - find and verify superblock...
> xfs_repair: error - read only 0 of 512 bytes

stracing those to see where it is failing to read might be useful.

It seems that your device has somehow shrunk out from under your fs.

-Eric

> 
> 'testdisk' does find the filesystem as XFS 4 and i created a 1.5TB dump of it to another hdd.
> 
> Is there any way I can fix this? - Except restroring from backup? Because this IS my backup!
> see ubuntuforums.org/showthread.php?t=1910962 for more details…
> 
> 
> Any help is appreciated!
> 
> Thanks in advance
> Chris
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> 

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