WARNING: <file> failed verification -- update discarded (will try again).

Joe Peterson joe at skyrush.com
Wed Dec 7 20:00:31 GMT 2005

Wayne Davison wrote:
> It is telling you that the updated file that rsync created didn't match
> the checksum that the sender told us.  There are a number of different
> ways this can happen (all of them pretty rare, but not impossible):

Thanks for clearing this up!

>     - A block checksum may have gotten a match on some local data that
>       wasn't really identical, so the constructed file wasn't correct.
>       (The redo-pass uses a slightly different block size in order to
>       work-around such a rare occurrence.)

I wonder if this could be it.  The file in question may mainly differ,
overall, from the original file as an offset of bytes, since it is
compressed audio that was shifted by only 120 samples in the new
version.  I wonder if that "subtle" change could increase the
probability of block checksums matching.

>     - If someone was modifying the file on the receiving side during the
>       interval between rsync generating the checksum data and the local
>       data being used to recreate the updated file, that can also cause
>       the end result to be incorrect (due to different data being copied
>       from what rsync was expecting).

Not the case here.

>     - If the data being sent over the socket was corrupted (somehow), it
>       may be that the corruption to occurred inside the file data.  This
>       is usually only possible with failing hardware, buggy networking
>       drivers, and things like that.

Hmm, hope not.  It's on a directly attached ethernet with HW that's been
stable over time with ECC memory, etc.  But who knows.  This is
certainly a scary possibility.  I checked the SMART logs on my hard
drives and they show no issue, so that's good.  The ethernet connection,
unless, as you say, there were a driver issue, should be TCP protected
(I am not specifying "-e", but it appears rsync chooses ssh as the
method by default).

I suppose I could have tripped upon an very obscure bug, but that's
probably unlikely (and yet most people would never catch the warning if
it had scrolled off their screen, so who knows how common it is).


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