On Mon, Sep 30, 2013 at 6:33 AM, Chris Adamson
<chris.adamson AT mcri.edu DOT au> wrote:
> The idea of using --whole-file is that rsync behaves like tar and I thought 
> that I could set --whole-file so that the rsync method would behave like the 
> tar method and compare byte by byte rather than using checksums. I had a look 
> both in the rsyncp and BackupPC code (RsyncFileIO.pm). The use of checksums 
> is intrinsic in the way that the rsync transfer method works. So it uses the 
> full file MD4 checksums to determine whether a file has changed at all. 
> Whether it uses the whole file option for transferring changed files is 
> unimportant since 99% of our files don't generally change between fulls. 
> After poking around it seems that the --whole-file option is specific to the 
> actual rsync tool and the BackupPC code along with RsyncP send a customized 
> set of commands to the rsync server. So it appears that not all of the rsync 
> "program" options are applicable. Maybe we already knew this but yeah this 
> concludes my investigation of --whole-file. I have attached a patch file that 
> doesn't add the --ignore-times argument to a full backup. It is based on 
> backuppc 3.2.1.
>

I think --whole-file is passed to, and handled by, the remote sender,
but it is only going to make a difference if you have large files with
small changes that take more time to merge than to send the whole
thing.

With your --ignore-times patch you will lose the 'safety factor' of
checking the content (and underlying media) periodically, which may be
more important in a de-duping environment where only one backup copy
of the content will exist.  You might want to back it out for
occasional weekend runs or something like that.

-- 
  Les Mikesell
     lesmikesell AT gmail DOT com

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