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Re: xfs_repair of critical volume

To: Eric Sandeen <sandeen@xxxxxxxxxxx>
Subject: Re: xfs_repair of critical volume
From: Eli Morris <ermorris@xxxxxxxx>
Date: Mon, 1 Nov 2010 16:32:54 -0700
Cc: xfs@xxxxxxxxxxx
In-reply-to: <4CCF3D68.6060201@xxxxxxxxxxx>
References: <75C248E3-2C99-426E-AE7D-9EC543726796@xxxxxxxx> <4CCF3D68.6060201@xxxxxxxxxxx>
On Nov 1, 2010, at 3:21 PM, Eric Sandeen wrote:

> On 10/31/10 2:54 AM, Eli Morris wrote:
>> I have a large XFS filesystem (60 TB) that is composed of 5 hardware
>> RAID 6 volumes. One of those volumes had several drives fail in a
>> very short time and we lost that volume. However, four of the volumes
>> seem OK. We are in a worse state because our backup unit failed a
>> week later when four drives simultaneously went offline. So we are in
>> a bad very state. I am able to mount the filesystem that consists of
>> the four remaining volumes. I was thinking about running xfs_repair
>> on the filesystem in hopes it would recover all the files that were
>> not on the bad volume, which are obviously gone. Since our backup is
>> gone, I'm very concerned about doing anything to lose the data that
>> will still have. I ran xfs_repair with the -n flag and I have a
>> lengthly file of things that program would do to our filesystem. I
>> don't have the expertise to decipher the output and figure out if
>> xfs_repair would fix the filesystem in a way that would retain our
>> remaining data or if it would, let's say t!
> One thing you could do is make an xfs_metadump image, xfs_mdrestore
> it to a sparse file, and then do a real xfs_repair run on that.
> You can then mount the repaired image and see what's there.
> So from a metadata perspective, you can do a real-live repair
> run on an image, and see what happens.
> -Eric

Hi Eric,

Thanks for the suggestion. I tried is out and this is what happened when I ran 

# xfs_mdrestore -g xfs_dump_image vol5_dump
xfs_mdrestore: cannot set filesystem image size: File too large

Any ideas? Is the file as large as the volume or something? I think you had a 
really good suggestion. If you know how to make this work, I think that would 
be great.



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