rsync - Jun 2007 - how to disable all checksum calculations?

Hi,

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.

Regards,

Bastiaan Bakker
E.Novation LifeLine Networks bv
  
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On 6/7/07, Bastiaan Bakker <Bastiaan.Bakker@enovation.nl>
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 .

Matt
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