Re: [rdiff-backup-users] Unchanged Files Being Incremented

[Andrew Ferguson]

On Feb 1, 2009, at 10:23 AM, Austin Roberts wrote:
> I'm doing a backup (from Windows to Linux, though I'm not sure  
> that's relevant), and I've noticed that a lot of files (especially  
> pictures) that haven't changed at all are being incremented. It will  
> say "Processing changed file ..." "Incrementing mirror file ..."  
> Even though the file hasn't changed at all. The resulting diffs are  
> generally between 9 and 141 bytes.

Backing up from Windows to Linux is relevant because rdiff-backup  
inspects the metadata on the file to determine whether it has changed  
and should be backed up. Getting the algorithm right becomes more  
complicated with platforms as different as Windows and Linux.

In order to help you, you're going to have to describe your situation  
some more. What version of rdiff-backup are you running on each end?  
Is it the native Windows client or the Cygwin client? How are you  
doing the backup? If you gunzip one of the diff.gz files, what does it  
say? (it will be in binary, use hexdump) ... What does md5 report for  
the "different" files? How large are the files which are being marked  
as "changed"?


> I found a discussion of this from 2004, and the consensus seemed to  
> be that these were unique rsync deltas, even though the file hadn't  
> changed. Someone fixed it by doing md5sums of the files on each side  
> to make sure they were different before storing anything.

Can you send a link to that discussion? Given it's age, it's probably  
not relevant to your particular situation. The rdiff-backup code has  
changed a lot in the last five years.


thanks,
Andrew