On Wed, Dec 21, 2011 at 8:50 PM, JP Vossen <jp AT jpsdomain DOT org> wrote:
>
> If I 'ddrescue' BAD --> GOOD, I'll worry about the integity of the
> BackupPC store. As I understand it, the incoming files are hashed and
> stored, but the store itself is never checked (true?). So when I do
> backups, if an incoming file hash matches a file already in the store,
> the incoming file is "de-duped" and dropped. But what if the file
> actually in the store is corrupt due to the bad disk?
>
> Am I correct? If so, is there a way to have BackupPC validate that the
> files in the pool actually match their hash and weren't mangled by the disk?
>
I'm not 100% sure, but I think the file contents are compared in order
to detect hash collisions. Also, if you do not have rsync checksum
caching enabled, an rsync full will compare the local and remote
copies and make a new local file if there are differences. Even when
you do have caching enabled a small percentage of the local files are
read for the comparison on each run to detect corruption. If you want
to verify the data, you could restore all or part of a host to some
other location, then run rsync with the -anv options against the
original. The -n will make it a 'dry run' and not actually transfer
anything, and the -v option will make it list files where differences
are found.
--
Les Mikesell
lesmikesell AT gmail DOT com
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