Rsync completed successfully, but files are not identical

Mark, Oren oren.mark at
Sun Aug 16 04:17:56 MDT 2009

BTW - Could it be because 2 rsync were running in parallel? 

Oren Mark

-----Original Message-----
From: Mark, Oren 
Sent: Sunday, August 16, 2009 1:01 PM
To: Matthias Schniedermeyer
Cc: rsync at; Mark, Oren
Subject: RE: Rsync completed successfully, but files are not identical

The only thing I can think about is backup program that change the atime after the backup and indeed, there was backup running at the time of this rsync.
But I am still trying to picture the scenario and I can't get it, since the file attributes are the same and only the data is not identical.  

You mean that the file was change while the access time value was update by the backup and then it was restored backup by the backup program, so it doesn't have the correct atime and mtime? 

Oren Mark

-----Original Message-----
From: Matthias Schniedermeyer [mailto:ms at] 
Sent: Sunday, August 16, 2009 12:20 PM
To: Mark, Oren
Cc: rsync at
Subject: Re: Rsync completed successfully, but files are not identical

On 16.08.2009 11:38, Mark, Oren wrote:
> Hi All,
> I came into a strange issue running rsync on directory with ~500,000 files.
> Some of the file, although with same time stamps and size on source and destination, were different on the destination.
> The destination is just a mirrored area, and the data written to it, is just the one that comes through rsync.
> Needless to mentioned, that when I remove files and synced them again it works, or when I did the sync with checksum.
> Due to the large number of files, running it with checksum is very bad options for me.
> I have few questions:
> 1)      Any idea how come a replicated area, has files with same time stamp and size, but file is different than the source?
> 2)      Is there a way for rsync to verify, that each transferred size is identical as the source, after the file was transferred?

My first question would be if i have a program on the source side that 
"tampers" with files and then resets the atime/mtime, as long as the 
size stays the same it's the same file for rsync.

And i faintly remember reading about an issue with mtime and mmap 
writing files. I don't remember the details, but i guess if there was an 
issue it is remedied in recent kernels.

IOW i'm quite sure the culprit isn't rsync.

Bis denn

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