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Date: Wed, 23 Sep 2009 14:25:16 +0200
From: Andreas Heinlein <aheinlein AT gmx DOT com>
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Subject: Re: Rsync and Alternate Data Streams
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Corinna Vinschen schrieb:
> On Sep 23 13:34, Andreas Heinlein wrote:
>   
>> Hello,
>>
>> no, I do *not* want to transfer ADS with rsync, that would be an FAQ ;-)
>>
>> But I have setup rsyncd on a windows host using cygwin. This machine
>> hosts files with ADS which are created by Antivirus software and change
>> frequently. I do not need to save these ADS, but somehow they seem to
>> lead rsync to believe the file has changed and transfer it again. Since
>> we are doing multi-generation backups with rsync and hard links (using
>> the --link-dest option), this greatly increases space requirements. I
>> compared old and new files, and they are exactly identical in size,
>> name, path, permissions (as UNIX/cygwin sees them), they have the same
>> md5sum.
>>
>> I have not yet tried running rsync with the checksum option, but since
>> we are backing up > 200.000 files, that would likely take much too long.
>> Do you have any ideas how to change this behaviour?
>>     
>
> Look for the rsync --size-only option.  Probably the Antivirus stuff
> changes the modification date, which is usually used by rsync for a
> quick decision what has changed.
>
> Alternatively use another Antivirus software which does not modify the
> files on disk.
>
>
> Corinna
Hello,

thanks for your reply. It turned out I had not checked closely enough. I
found out it has nothing to do with ADS, but with file ownership. Some
of the files in question have UID and GID 4294967295 (aka 2^32-1),
though they are owned by a valid Domain User. Rsync on the UNIX side
sets the UID to 0 for these files, I overlooked this. I can work around
this now by not preserving owner and group, which is not necessary in
this case.
But I still wonder where this comes from.

Bye,
Andreas

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