rsync - Jun 2010 - Source files in use or modified while transfer

Hi!

I have a question on rsync's way to deal with files in use
or files that are modified on the source while they
are transferrred to the destination.

Yes, I searched the web and found
> In rsync, transfers are done to a temporary file, which is cut over 
> atomically, so the transfer either happens in its entirety or not at 
> all. Basically, rsync does "the right thing," so you won't
end up with
> partially-backed-up files. 
and
> On the destination rsync always writes to a temporary file and then
> renames it.  This operation is atomic on Unix, so processes will
> either see the old file or the new one.  Processes that have the old
> file open it will continue to use it even after it's been unlinked.
>   
Well, but this only describes how rsync is dealing with files
on the destination directory.

But what if e.g. a large mailbox file is changed on the source directory.

Is there a checksum check after the transfer and if  yes - how often is 
the file
transferred again by default.

Is rsync working with a shadow copy of the source files?

I hope you can help me.

Thanks!

Homer

HomeRun4711 (homerun4711 at googlemail.com) wrote on 3 June 2010 11:27:
 >I have a question on rsync's way to deal with files in use
 >or files that are modified on the source while they
 >are transferrred to the destination.
[removed]
 >But what if e.g. a large mailbox file is changed on the source directory.

In the source the file is read only once. Changes that happen during
the transfer ahead of the point where rsync is reading are
transmitted, changes before that position are not.

 >Is there a checksum check after the transfer and if yes - how often
 >is the file transferred again by default.

The checksum is applied to what's been transmitted. There's no
re-reading of the file at either end.

 >Is rsync working with a shadow copy of the source files?

No.