how to disable all checksum calculations?

Bastiaan Bakker Bastiaan.Bakker at
Tue Jun 12 21:03:00 GMT 2007

Hi Math,

Thanks a lot! This is exactly what I was looking for. The checksumming of the appended part is fine.



PS. Sorry for top posting but his crappy Outlook web thingy does not indent the original message. 

-----Original Message-----
From: hashproduct at on behalf of Matt McCutchen
Sent: Tue 12-Jun-07 22:06
To: Bastiaan Bakker; Wayne Davison
Cc: rsync at
Subject: Re: how to disable all checksum calculations?
On 6/7/07, Bastiaan Bakker <Bastiaan.Bakker at> wrote:
>  I've a directory of large log files (> 100M) that I want to rsync to
>  another server in short intervals (say every minute).
>  With the --append option I can avoid resending whole files at every
>  sync. But rsync still calculates the checksum over the complete files
>  every time, which claims a significant share of CPU and IO resources.
>  Since the log files are always written in append-only mode, I'm
>  confident that --append mode correctly reconstructs the files at the
>  remote server, so I would like to get rid of the checksum calculation.
>  AFAIK rsync doesn't have an option to disable all checksum calculations
>  (please let me know if I'm wrong). I looked at the source code to add it
>  myself, couldn't figure where to turn off the calculation and to signal
>  the peer.
>  If anyone could drop a hint as to what the right approach would be, that
>  would be appreciated very much.

Correct, rsync has no option to disable the post-transfer checksum
completely.  I implemented a patch to rsync 2.6.9 that adds an option
--trust-append that limits the post-transfer checksum to the added
portion, not the entire file.  The patch is attached.  That should be
good enough, but if you really want to disable the checksum
completely, just comment out the remaining sum_update calls in match.c
and receiver.c .

Wayne, perhaps you would like to add a converted version of the patch
to patches/ of the CVS like you did for --source-backup .


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