Re: Problem on Fedora Core 4

["Adam T. Bowen" <adamb@agitate.org.uk>]

Hi,

Bargel Jazat wrote:
[snip]
> The first time the problem appeared like this: I mirrored some 
> directories to
> my second hard disk and when I made a diff
> 
> $ diff -ru <source dir> <target dir>
> 
> I found that the two subtrees were not the same. A few binary
> files were different, one text file differed in exactly one character.

Do the files change size or just content?  Can you send an example diff?

> The copy was made with rsync, can it be a bug with rsync?
[snip]
> I copied a file from my laptop to the desktop. I copy everything to the 
> _new_
> hard disk, which is hopefully ok.
> It is a long tar/gzip archive (1.4 GB). I also copied a MD5SUM of the 
> file and
> when I verified the MD5SUM I got an error. In fact the archive was 
> corrupted
> and wouldn't unpack.
> 
> Problem with rsync? Or with ssh (the problem also occurs with scp)?

Newer versions of rsync are configured by default to use scp so it could 
have been a problem with that, but you say you did a 'mirror' of your 
hard disk.  I am presuming you used a back to back tar to do that?  If 
so then it can't be a problem with any one of these packages.

> Next trial was to split the file in small files, send them individually 
> together
[snip]
> I run md5sum -c ...
> I get an error.
> I run md5sum -c ...
> again on the same file, it verifies OK!

A rootkit could cause that sort of a problem I suppose.  Some of them 
modify checksum programs (badly).  I have used this rootkit checker before:

       http://www.chkrootkit.org/

> Now I am totally confused, how can this be? This means that the _same_
> file had different content after 10 seconds.
> 
> Can this be some hardware problem? Maybe the disk controller?

I would virus and rootkit scan the computer for starters.  If you don't 
find anything then try just copying a whole load of files from one 
directory on the suspect disk to another on the same disk and then diff 
those.  If that causes errors then I suppose it could be a fault with 
the disk or controller.  Is the disk your root disk?  If so then I would 
expect the OS to be pretty unstable too.  It could also be an OS 
problem.  You could try booting with a rescue CD such as Knoppix and do 
the same tests and see if the files still get corrupted.  If so, then 
the case for faulty hardware is strong.  If not, then you could try 
reinstalling/repairing the OS.  FC4 is pretty bleeding edge, so it could 
be that you reinstall the OS and still get the same problems.  In that 
case you could try a different distro I suppose.

Sorry I can't be more help.

Cheers

Adam


> Thanks for any suggestion
> Giorgio
> 
> 
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