xfs_metadump as a backup tool

[Gionatan Danti <g.danti@assyoma.it>]

Hi all,
I wish to ask if someone is using xfs_metadump as a "real" backup tool - 
ie: in production.

I was wondering how to lower recovery time in case of filesystem 
corruption, and the idea of using xfs_metadump + xfs_mdrestore struck 
me.

I plan to have a single, relatively big XFS volume with an handfull of 
fully preallocated large files (VM disk images). Basically, I was 
thinking about:
- take a LVM snapshot;
- mount the snap volume as read-only;
- copy the user data (via tar/rsync/whatever);
- additionally, xfs_metadump its metadata content.

If a major filesystem corruption occour, as a first step I should be 
able to simply restore its metadata with xfs_mdrestore and re-gain 
access to files/data blocks. A potential pitfall would be related to 
extents that at the time of xfs_metadump where marked as "unwritten" but 
later were written - restoring the old metadata will immediately turn 
user data into zeroes. It is possible to fully allocate a file *without* 
marking the allocated extents as "unwritten"? Yes, I know this has 
security implications...

Is this a good idea? I am missing something?
Thanks.

-- 
Danti Gionatan
Supporto Tecnico
Assyoma S.r.l. - www.assyoma.it
email: g.danti@assyoma.it - info@assyoma.it
GPG public key ID: FF5F32A8