Re: [rdiff-backup-users] rdiff-backup changes .gz files

[Arno Wagner]

Hi,

I found a bit more time and found also some .pm files
with the same issue. Looking into the files though,
I have a suspicion, namely that for some reason these
files were changed by a Debian update, that then did 
set the same original metadata after installing new 
files. The suspicion comes from the differences being date
format changes only, no corruption at all.

So new question: Is there a way to make rdiff-backup
actually do a checksum comparison for exisitng files in
order to determine what to backup? I know, that would
be significantly slower, but as least on Debian system
partitions, a metadata comparison is obviously not 
enough. As a substitute, can I force rdiff-backup
to backup specific files even if the metadata
is the same? 

Regards,
Arno




On Sat, Jul 09, 2011 at 10:19:59PM +0200, Arno Wagner wrote:
> Hi,
> 
> I do full Linux root partition backups with rdiff-backup
> 1.2.8 on Debian squeeze. As I have had numerous instances of
> silent corruption, I always verify my backups, in this case with
> 
>   rdiff-backup --compare-full --exclude-sockets --exclude-other-filesystems 
> 
> This verify gives me several "metadata the same, data changed" 
> errors, that do not make sense. Examples are
> 
>    /usr/share/doc/libssl-dev/demos/tunala/INSTALL.gz
>    /usr/share/doc/lrzsz/NEWS.gz
>    /usr/share/doc/openssl/doc/apps/rsa.pod.gz
>    /usr/share/doc/xfig/LATEX.AND.XFIG.zh_CN.gz
> 
> When I compare manually, these files are indeed different, 
> but gzip -tv tells me both are fine and they decompress 
> to bit-identical files. 
> 
> One thing I have noticed is that these files are all pretty old.
> 
> What is going on here? As I also use md5sum for integrity checks,
> modifying .gz files in a backup is really not a good idea., even
> if they decompress the same. In fact changing anything when backing 
> up files is not a good idea. Also, with this problem, I have to 
> check manually for each verification error whether it is truely an 
> error or an instance of this not-really corruption.
> 
> To me this looks like a bug in rdiff-backup. 
> I have observed this only with .gz files.
> 
> Arno
> -- 
> Arno Wagner, Dr. sc. techn., Dipl. Inform., CISSP -- Email: address@hidden 
> GnuPG:  ID: 1E25338F  FP: 0C30 5782 9D93 F785 E79C  0296 797F 6B50 1E25 338F
> ----
> Cuddly UI's are the manifestation of wishful thinking. -- Dylan Evans
> 
> If it's in the news, don't worry about it.  The very definition of 
> "news" is "something that hardly ever happens." -- Bruce Schneier 

-- 
Arno Wagner, Dr. sc. techn., Dipl. Inform., CISSP -- Email: address@hidden 
GnuPG:  ID: 1E25338F  FP: 0C30 5782 9D93 F785 E79C  0296 797F 6B50 1E25 338F
----
Cuddly UI's are the manifestation of wishful thinking. -- Dylan Evans

If it's in the news, don't worry about it.  The very definition of 
"news" is "something that hardly ever happens." -- Bruce Schneier