Re: [rdiff-backup-users] Weird behavior of rdiff-backup : founding diffs while there isn't

[Matthieu . Rioteau]

Hi Nicolas,

I do not suspect any hardware failure (as this machine is running very 
fine), but will nevertheless carefully check it.

Thanks for the tip.

Regards,
Matthieu

> From: address@hidden
> To: address@hidden
> Date: 17/11/2012 18:18
> Subject: Re: [rdiff-backup-users] Weird behavior of rdiff-backup : 
> founding diffs while there isn't
> Sent by: address@hidden
> 
> Hi Matthieu,
> 
> I had only a quick read of your mail, but for me it smells hardware 
> problem. Have you cross-checked your cables, interfaces and storage 
medium?
> 
> Regards,
> Nicolas
> 
> On 2012-11-16 11:21, address@hidden wrote:
> > Hi all,
> >
> > I recently decided to choose rdiff-backup as backup tool on 2 Linux
> > machines.
> >
> > One is running it perfectly.
> >
> > But the other one has a strange behavior when running rdiff-backup.
> > Actually, it find differences in a lot of files while there isn't any.
> > This leads to rdiff-backup overwriting a lot of files for nothing and
> > taking a long time.
> >
> > Let me take an example to clarify things.
> >
> > Consider I already have 2 backups done on a daily basis (let me call 
them
> > A and B chronologically -- thus B is the current mirror).
> >
> > I run 'rdiff-backup --compare' just before backing up : it returns "no
> > changes"
> >
> > I run the back up and here rdiff-backup finds thousand of files that 
have
> > changed (viewed from session statistics) !!!
> > This backup is called C and is the new mirror.
> >
> > When I look at the file statistics, a lot of files are marked as 
changed.
> > The first weird thing here is that IncrementSize is not null while
> > SourceSize and MirrorSize are identical (IncrementSize is always a 
small
> > number - <128 -).
> >
> > For example : home/USER/.kde/share/config/katerc 1 67 67 66
> >
> > Ouch!
> > Second weird thing is that absolutely no diff between C and B is 
stored
> > nor in the data itself, nor in the metadata
> >
> > Now looking at the source files : their access times (and only these 
ones)
> > have been updated at the time of the backup (thus rdiff-backup does
> > something that changes this).
> > Looking at the destination files : their access and change times have 
been
> > updated also but not the modify time.
> >
> > Last very weird thing : if I run a rdiff-backup --compare-at-time 1B 
(thus
> > comparing current files with old B backup), it returns "no changes" 
...
> > !!!
> >
> > At now my thinking is that rdiff-backup views a difference while there
> > isn't when running in the backing up context but clearly see that 
there
> > isn't in the comparing context.
> >
> > I also runned a rdiff-backup --compare every 5 minutes with a cronjob 
and
> > it always return "no changes" except at the time where the backup 
started.
> > Thus it seems that riff-backup is itself fooling itself... But not 
sure
> > because if I run things manually (instead of cronjob), everything 
works
> > fine.
> >
> > I don't know why I'm having this behavior at now but for sure I'd like 
to
> > prevent it to appear. ;-)
> >
> > Did anyone already have this behavior ? And eventually found the cause 
and
> > fix that ?
> >
> > As information, below the characteristics of the system (and between
> > parenthesis the ones of the other machine when everything works well 
as
> > comparison).
> >
> >   - rdiff-backup version : 1.2.8 (1.2.8)
> >   - OS : Kubuntu 11.04 (Debian Wheezy)
> >   - kernel : 2.6.38 (3.2.0)
> >   - launching way : cronjob (cronjob)
> >   - source FS : ext4 (ext3)
> >   - destination FS : ext4 (ext4)
> >
> > So basically only noticeable difference is a quite old kernel on the
> > screwing up machine.
> >
> > I will increase verbosity of rdiff-backup and keep you updated.
> >
> > In between, thanks in advance for any help and support. Feel free to 
ask
> > if missing information can help.
> >
> > Best regards,
> > Matthieu
> >
> > _______________________________________________
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> RdiffBackupWiki
> >
> 
> 
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